KR101453473B1 - Electro-Optic Modulating Device - Google Patents

Abstract

An electro-optic modulation element is provided. The device has an optical waveguide in which a vertical structure having at least two sidewalls is formed, the sidewalls of the vertical structure being used to construct the junction.

Description

[0001] Electro-Optic Modulating Device [0002]

The present invention relates to a photonic device, and more particularly to an electro-optic modulation device.

The present invention is derived from a research carried out as part of the IT-originated technology development project of the Ministry of Knowledge Economy [assignment number: 2006-S-004-04, title: Silicon-based high-speed optical interconnection IC].

Silicon photonics technology is becoming increasingly important as an alternative technology to solve severe thermal problems inside increasingly emerging computing devices and bottlenecks in data communication between semiconductor chips. Over the past few years, there has been a major advance in silicon photonics technology. For example, fast silicon optical modulators, Si-Ge photo-detectors, silicon Raman lasers, silicon optical amplifiers, silicon wavelength converters silicon wavelength converters and hybrid silicon lasers have been developed. Nevertheless, until recently, the fastest data transfer rate, implemented using a silicon modulator, was approximately 10 Gb / s. In order to meet the increase in bandwidth required in next generation communication networks and future high performance computing devices, it is necessary to realize much faster modulation and data transmission characteristics.

Commercialized high-speed optical modulators are mostly based on electro-optic materials such as lithium niobate and III-V semiconductors and provide modulation characteristics of approximately 40 Gb / s (much faster than 10 Gb / s) It is known. On the other hand, since monocrystalline silicon is a material that does not have a linear electro-optical characteristic (i.e., a Pockels effect) but exhibits a very weak Franz-Keldysh effect, Implementing the properties was difficult.

Although it has recently been known that strained silicon exhibits the above-described Foquel effect, the measured electro-optic coefficient is much smaller than LiNbO ₃ . It is also known that strained Ge / SiGe quantum well structures have relatively high electro-optic absorption properties by the Quantum Confined Stark effect Although known, there are still a number of technical issues (eg, strain engineering) that need to be addressed to implement this.

To date, fast modulation in silicon can only be realized through the free carrier plasma dispersion effect. In silicon, the change in free charge density results in a change in the refractive index of the material, and thus the modulation rate of the silicon modulator based on the free charge plasma dispersion effect is determined by how fast free charges can be injected or removed. The proposed device configuration for implementing phase modulation in silicon is largely divided into a forward biased pin diode, a MOS capacitor and a reverse bias pn junction biased pn junctions).

It has been demonstrated that the forward-bias pieze diode approach, illustratively disclosed in U.S. Patent No. 5,908,305, can provide high modulation efficiency. However, because of the slow charge generation process and the slow recombination process, the pure-bias piezane diode approach has a limitation on the modulation rate as long as it can not significantly reduce the charge life.

Both the MOS capacitor and the reverse-bias Pn junction are based on electric field induced majority carrier dynamics, which potentially can achieve 10 Gb / s or more. However, due to the low modulation efficiency, these schemes require long length phase-modulators. In addition, in the case of the reverse-bias pn junction method disclosed in U.S. Patent Publication No. 2006/0008223, there is a technical problem that the entire optical waveguide for the phase-modulation is doped to a considerably high degree, resulting in a large optical wave loss.

One of the problems to be solved by the present invention is to provide a high-performance electro-optic modulation device that provides high speed, high modulation efficiency, small size, low power consumption and low luminance wave loss characteristics.

An electro-optic modulation element is provided that includes a locally doped region in the optical waveguide. The device has an optical waveguide formed with a vertical structure having at least two side walls, and the side walls of the vertical structure are used to form a junction.

According to an embodiment, the thickness of the optical waveguide may be smaller than the sum of the lengths of the side walls of the vertical structure projected on a plane perpendicular to the traveling direction of the optical waveguide.

According to one embodiment, the optical waveguide includes a first slab portion, a second slab portion, and a rib portion interposed between the first and second slab portions And the vertical structure is formed in the lip portion.

According to one embodiment, the optical waveguide includes a first body region extending from the first slab portion and contacting one side wall of the vertical structure, and a second body region extending from the second slab portion and contacting the other side wall of the vertical structure, Region. ≪ / RTI > The first and second body regions may be of a first conductivity type and the vertical structure may include at least one vertical doped region having a second conductivity type different from the first conductivity type.

According to one embodiment, the first and second body regions and the vertical structure constitute a pair of PN junctions, wherein a vertical length of the vertical structure is greater than a thickness of the first slab portion And is less than half of the sum of the lengths of the p-junctions projected on a plane perpendicular to the traveling direction of the optical waveguide.

According to an embodiment, the semiconductor device may further include a first wiring structure electrically connecting the vertical doped region and the first circuit, and a second wiring structure electrically connecting the slab portion and the second circuit. The first and second circuits may be configured to generate a potential difference for reverse-biasing operation of the pn junctions.

According to one embodiment, the first slab portion may include a first doped region of a first conductivity type, and the second slab portion may include a second doped region of the first conductivity type. In addition, the optical waveguide includes a first body region extending from the first doped region and in contact with a side wall of the vertical structure, and a second body region extending from the second doped region and contacting the other side wall of the vertical structure can do. The first and second body regions may be formed of an intrinsic semiconductor and the vertical structure may include at least one vertical doped region having a second conductivity type different from the first conductivity type.

According to one embodiment, the first doped region, the first body region, and the vertical structure form a PIN-junction, and the second doped region, the second body region, The pi-ene junction can be constructed.

According to an embodiment, the semiconductor device may further include a first wiring structure electrically connecting the vertical doped region and the first circuit, and a second wiring structure electrically connecting the slab portion and the second circuit. The first and second circuits may be configured to generate a potential difference for net-bias operation of the piezane junctions.

According to one embodiment, the thicknesses of the first and second doped regions may be substantially equal to the thicknesses of the first and second slab portions, respectively.

According to one embodiment, the vertical structure may include a plurality of vertical doped regions and at least one inner region interposed between the vertical doped regions.

According to one embodiment, the at least one inner region includes an inner doped region having a conductivity type different from that of the vertical doped regions, thereby forming a PN junction with the vertical doped regions.

According to an embodiment, the at least one inner region includes a pair of intrinsic regions and an inner doped region interposed between the intrinsic regions and having a conductivity type different from that of the vertical doped regions, And at least two pi-junctions (PIN-junctions).

According to one embodiment, the first slab portion includes a first doped region of a first conductivity type, and the second slab portion includes a second doped region of the first conductivity type, The first and second doped regions may be electrically connected to circuits generating different voltages.

According to one embodiment, the first slab portion includes a first doped region of a first conductivity type, and the second slab portion includes a second doped region of the first conductivity type, The first and second doped regions may be electrically connected to each other to be in an equipotential state.

According to one embodiment, the first slab portion includes a first doped region of a first conductivity type, and the second slab portion includes a second doped region of a second conductivity type different from the first conductivity type . In this case, the vertical structure may include a first vertical doping region having the second conductivity type and formed adjacent to the first slab portion, and a second vertical doping region having the first conductivity type and being formed adjacent to the second slab portion 2 vertical doped regions.

According to one embodiment, the optical waveguide further includes an embedded insulating film disposed under the optical waveguide, wherein the optical waveguide may have a channel waveguide structure formed to have a side wall exposing an upper surface of the embedded insulating film.

According to the present invention, there is provided an electro-optic modulation element in which a plurality of vertical pien junctions or a plurality of vertical pi-ene junctions are formed in an optical waveguide. Because the pien junctions or the pi-ene junctions can increase the effective refractive index change during device operation, a high performance optical modulator with high speed, high modulation efficiency, small size, low luminous intensity wave loss, and low power consumption characteristics Can be implemented.

Figs. 1A and 1B are cross-sectional views showing cross-sections of electro-optic modulation elements according to a first embodiment of the present invention.
1C is a graph illustrating a forward-doping profile of the electro-optic modulation device according to the first embodiment of the present invention.
FIGS. 2A and 2B are cross-sectional views showing cross sections of electro-optic modulation elements according to a first modification of the present invention.
FIG. 2C is a graph illustrating a forward-doping profile of an electro-optic modulation device according to a first modification of the present invention. FIG.
3A and 3B are cross-sectional views showing cross-sections of electro-optic modulation elements according to a second modification of the present invention.
FIG. 3C is a graph illustrating a forward-doping profile of an electro-optic modulation device according to a second modification of the present invention. FIG.
4A is a cross-sectional view illustrating an electro-optic modulation device according to a second embodiment of the present invention.
FIG. 4B is a graph illustrating a pure-doped profile of an electro-optic modulation device according to a second embodiment of the present invention.
5A is a cross-sectional view showing cross sections of electro-optic modulation elements according to a third modification of the present invention.
FIG. 5B is a graph illustrating a forward-doping profile of an electro-optic modulation device according to a third modification of the present invention. FIG.
6A and 6B are cross-sectional views showing cross sections of electro-optic modulation elements according to a fourth modification of the present invention.
FIG. 6C is a graph illustrating a forward-doping profile of an electro-optic modulation device according to a fourth modification of the present invention. FIG.
7A is a cross-sectional view showing cross sections of electro-optic modulation elements according to a fifth modification of the present invention.
FIG. 7B is a graph illustrating a forward-doping profile of an electro-optic modulation device according to a fifth modification of the present invention.
8A to 8C are cross-sectional views showing cross sections of electro-optic modulation elements according to a sixth modification of the present invention.
Figs. 9A and 9B are cross-sectional views showing cross sections of electro-optic modulation elements according to a third embodiment of the present invention.
10A and 10B are cross-sectional views showing cross-sections of electro-optic modulation elements according to a fourth embodiment of the present invention.
11 is a block diagram schematically illustrating an embodiment of an optical system including an optical transmitter and an optical receiver according to embodiments of the present invention.
12 is a diagram showing an embodiment of an optical modulator that can be employed as the optical device of Fig.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features, and advantages of the present invention will become more readily apparent from the following description of preferred embodiments with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments disclosed herein are provided so that the disclosure can be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

In this specification, when it is mentioned that a film is on another film or substrate, it means that it may be formed directly on another film or substrate, or a third film may be interposed therebetween. Further, in the drawings, the thicknesses of the films and regions are exaggerated for an effective explanation of the technical content. Also, while the terms first, second, third, etc. in various embodiments of the present disclosure are used to describe various regions, films, etc., these regions and films should not be limited by these terms . These terms are only used to distinguish any given region or film from another region or film. Thus, the membrane referred to as the first membrane in one embodiment may be referred to as the second membrane in another embodiment. Each embodiment described and exemplified herein also includes its complementary embodiment.

[First Example ]

Figs. 1A and 1B are cross-sectional views showing cross-sections of electro-optic modulation elements according to a first embodiment of the present invention. 1C is a graph illustrating a net doping profile of the electro-optic modulation device according to the first embodiment of the present invention. Specifically, FIG. 1C is a graph showing the forward-doping profile along the dashed line I-I 'of FIGS. 1A and 1B.

Referring to FIGS. 1A and 1B, a semiconductor film 30 constituting an optical waveguide WG is disposed on a substrate 10. The optical waveguide WG may be a slab waveguide structure including a first slab portion SP1, a second slab portion SP2 and a lip portion RP disposed therebetween, And may be formed to have a greater thickness than the first and second slab portions SP1 and SP2.

According to an embodiment of the present invention, the semiconductor film 30 may be formed of monocrystalline silicon. For example, the semiconductor film 30, together with the substrate 10, can constitute an SIO wafer. In this case, as shown, an embedded insulating film 20 may be disposed between the substrate 10 and the semiconductor film 30. The buried insulating layer 20 may be formed of an insulating material having a refractive index lower than that of the semiconductor layer 30 (for example, a silicon oxide layer) so that the buried insulating layer 20 may be used as a cladding layer of the optical waveguide WG. However, the technical idea of the present invention is not limited to the wafer structure or the kind of the thin film.

The first and second doping regions D1 and D2 may be formed in the first and second slab portions SP1 and SP2 and the vertical doping region (50) may be formed. According to this embodiment, the first and second doped regions D1 and D2 may be of a first conductivity type and the vertical doped region 50 may be of a second conductivity type different from the first conductivity type. For example, when the first and second doped regions D1 and D2 are p-type, the vertical doped region 50 may be n-type. Alternatively, when the first and second doped regions D1 and D2 are n-type, the vertical doped region 50 may be p-type.

According to this embodiment, a part of the optical waveguide WG interposed between the first doped region D1 and the vertical doped region 50 (hereinafter referred to as a first body region B1) And may be of the same conductivity type as the first doped region D1 (i.e., the first conductive type). That is, the first body region B1 may be doped with a different conductivity type than that of the vertical doping region 50. Accordingly, the first body region B1 and the vertical doping region 50 may form a PN junction as shown in FIG. 1C. Similarly, another portion of the optical waveguide WG (hereinafter referred to as the second body region B2) interposed between the second doped region D2 and the vertical doped region 50 is formed in the vertical doped region 50 ), The second body region B2 and the vertical doped region 50 may also form a pn junction.

Referring to FIG. 1A, the vertical doped region 50 may be formed such that its bottom surface contacts the upper surface of the buried insulating film 20. That is, the thickness of the vertical doped region 50 may be substantially equal to the thickness of the lip portion RP. In this case, as shown in the figure, the first body region B1 and the second body region B2 may be separated from each other by the vertical doping region 50. In addition, the vertical doped region 50 may be used as a common electrode of two p-n junctions defined by the first and second body regions B1 and B2. According to another embodiment of the present invention, the first body region B1, the vertical doped region 50, and the second body region B2 may constitute a bipolar junction transistor (BJT). In this case, the first doped region D1 and the second doped region D2 may be connected to different circuits which generate different voltages, unlike the one shown.

Referring to FIG. 1B, the thickness of the vertical doping region 50 may be smaller than the thickness of the lip portion RP. In this case, as shown, the first body region B1 may be connected to the second body region B2 below the vertical doping region 50. [ That is, the pn junctions constituted by the first and second body regions B1 and B2 may be connected under the vertical doping region 50. [ In this case, the length of the connected pn junction (which is projected on a predetermined plane intersecting the traveling direction of the lip portion RP) may be longer than twice the length of the vertical doped region 50.

1A and 1B are sectional views showing a cross section of an electro-optic modulation element projected on one of the planes crossing the traveling direction of the optical waveguide WG, Is not provided to show that the optical waveguide has a structure shown throughout the optical waveguide. That is, the electro-optic modulation device according to the present invention includes a portion formed in the cross-sectional structure shown in the drawings, but not all portions of the electro-optic modulation device need to be formed with the cross-sectional structure shown. For example, in a portion of the optical waveguide WG, the first body region B1 may have a portion directly contacting the second body region B2.

In addition, the first and second doped regions D1 and D2 may be doped with the same conductivity type and higher concentration than the first and second body regions B1 and B2, respectively. In addition, as shown in FIG. 1C, the vertical doped region 50 may be doped with a different conductivity type than the first and second body regions B1 and B2 and higher concentrations thereof. Although the abrupt junction structure is illustrated by way of example in FIG. 1C, the concentration profiles of the vertical doping region 50 and the first and second body regions B1 and B2, respectively, . For example, the p-junctions may be implemented as a linearly graded junction structure.

According to this embodiment, the vertical doped region 50 is electrically connected to a first circuit C1 that generates a first voltage V1 using a first wiring structure 91, 2 doped regions D1 and D2 may be electrically connected to the second circuit C2 that generates the second voltage V2 using the second wiring structure 92a and 92b.

According to an embodiment, the first voltage V1 and the second voltage V2 may be a modulation voltage and a ground voltage, respectively. Accordingly, a predetermined potential difference, which is determined by the first voltage V1, may be generated between the vertical doped region 50 and the first and second body portions B1 and B2. As described above, since both side walls of the vertical doped region 50 are all used to form the p-junction, the electro-optic modulation element according to the embodiment described with reference to Figs. It is possible to cause an increase in the effective refractive index to be changed, compared to the methods proposed. For example, the electro-optic modulation element according to this embodiment can cause about twice the effective refractive index change as compared to the method disclosed in U.S. Patent Publication No. 2006/0008223. This increase in the effective refractive index change makes it possible to obtain an increased phase shift or to make the length of the modulation region short in the optical waveguide. In particular, when the pn junctions operate in the PN reverse mode, the technical problem of highly doping the active region of the optical waveguide WG can be alleviated. That is, according to this embodiment, since it is possible to reduce the average doping level of the optical waveguide WG, the optical loss in the optical waveguide WG can be reduced.

[First Variation example ]

FIGS. 2A and 2B are cross-sectional views showing cross sections of electro-optic modulation elements according to a first modification of the present invention. FIG. 2C is a graph illustrating a forward-doping profile of an electro-optic modulation device according to a first modification of the present invention. FIG. Specifically, FIG. 2C is a graph showing the forward-doping profile along the dashed line I-I 'of FIGS. 2A and 2B. For brevity of description, the description of the technical features overlapping with the embodiments described with reference to Figs. 1A to 1C can be omitted.

Referring to FIGS. 2A and 2B, according to this embodiment, a vertical structure including two vertical doped regions 50 may be formed in the lip portion RP. In addition, the vertical structure may further include an inner doped region B3 interposed between the vertical doped regions 50. [

The inner doping region B3 is of the same conductivity type as the first and second body regions B1 and B2 and the vertical doping regions 50 are formed in the first and second body regions B1 and B2 Lt; / RTI > Accordingly, the rib portions RP can be formed with pn junctions having an increased length as compared with the embodiment described with reference to Figs. 1A to 1C. For example, as shown in FIG. 2A, the vertical doping regions 50 are formed to be in contact with the upper surface of the buried insulating film 20, so that each of the vertical doping regions 50 has two separated p- Can be used as the common electrode of the junctions. That is, according to the embodiment of FIG. 2A, as shown in FIG. 2C, four pie junctions may be formed in the lip portion RP. 2B, the vertical doped regions 50 are formed to be thinner than the thickness of the lip portion RP, so that the side surfaces and the lower surfaces of the vertical doped regions 50 are all connected to the p- Lt; / RTI > Thus, the length of the pi-junction of the optical device according to the embodiment of Fig. 2b can be approximately twice that of the optical device according to the embodiment of Fig. 1b.

2A and 2B, the vertical doped regions 50 are electrically connected to the first circuit C1 that generates the first voltage V1 using the first wiring structure 91 . According to one embodiment, as shown in FIG. 2A, the internal doped region B1 may be electrically connected to a second circuit C2 that generates a second voltage V2 using the internal wiring structure 92c have. According to another embodiment, as shown in FIG. 2B, the inner doped region B3 is electrically connected to the first and second body regions B1 and B2 at the bottom of the vertical doped regions 50 So that it can be in the equipotential state with the first and second body regions B1 and B2 without any additional wiring.

In operation, the first voltage V1 and the second voltage V2 may be a modulation voltage and a ground voltage, respectively. Accordingly, a predetermined potential difference, which is determined by the first voltage V1, may be generated between the vertical doped regions 50 and the first and second body portions B1 and B2. According to one embodiment, the first voltage V1 and the second voltage V2 may be selected such that the pn junctions operate in a Pn reverse mode.

[Second Variation example ]

3A and 3B are cross-sectional views showing cross-sections of electro-optic modulation elements according to a second modification of the present invention. FIG. 3C is a graph illustrating a forward-doping profile of an electro-optic modulation device according to a second modification of the present invention. FIG. Specifically, FIG. 3C is a graph showing the forward-doping profile along the dashed line I-I 'of FIGS. 3A and 3B. For brevity of description, the description of the technical features overlapping with the embodiments described with reference to Figs. 1A to 1C can be omitted.

Referring to FIGS. 3A and 3B, according to this embodiment, a vertical structure including three vertical doped regions 50 may be formed in the lip portion RP. In addition, the vertical structure may further include two internal doping regions B31 and B32 interposed between the vertical doping regions 50. [

The inner doping regions B31 and B32 are conductive types such as the first and second body regions B1 and B2 and the vertical doping regions 50 are formed in the first and second body regions B1, B2). Accordingly, the rib portions RP can be formed with pn junctions having an increased length as compared with the embodiment described with reference to Figs. 2A to 2C. For example, as shown in FIG. 3A, the vertical doping regions 50 are formed so as to be in contact with the upper surface of the buried insulating film 20, so that each of the vertical doping regions 50 includes two separated p- Can be used as the common electrode of the junctions. That is, according to the embodiment of FIG. 3A, as shown in FIG. 3C, six peen junctions may be formed in the lip portion RP. 3B, the vertical doped regions 50 are formed to be thinner than the thickness of the lip portion RP, so that the side surfaces and the lower surfaces of the vertical doped regions 50 are all connected to the pn junction Lt; / RTI > Thus, the length of the pi-junction of the optical device according to the embodiment of Fig. 3b can be approximately three times that of the optical device according to the embodiment of Fig. 1b.

3A and 3B, the vertical doped regions 50 are electrically connected to the first circuit C1 that generates the first voltage V1 using the first wiring structure 91 . According to one embodiment, as shown in FIG. 3A, the internal doping regions B31 and B32 are electrically connected to the second circuit C2 that generates the second voltage V2 using the internal wiring structure 92c . According to another embodiment, as shown in FIG. 3B, the internal doping regions B31 and B32 are electrically connected to the first and second body regions B1 and B2 at the lower portion of the vertical doping regions 50 So that they can be in the equipotential state with the first and second body regions B1 and B2 without any additional wiring.

In operation, the first voltage V1 and the second voltage V2 may be a modulation voltage and a ground voltage, respectively. Accordingly, a predetermined potential difference, which is determined by the first voltage V1, may be generated between the vertical doped regions 50 and the first and second body portions B1 and B2. According to one embodiment, the first voltage V1 and the second voltage V2 may be selected such that the pn junctions operate in a Pn reverse mode.

[Second Example ]

4A is a cross-sectional view illustrating an electro-optic modulation device according to a second embodiment of the present invention. 4B is a graph illustrating a net doping profile of the electro-optic modulation device according to the second embodiment of the present invention. Specifically, FIG. 4B is a graph showing the forward-doping profile along the dashed line I-I 'of FIG. 4A. For brevity of description, the description of the technical features overlapping with the embodiments described with reference to Figs. 1A to 1C can be omitted.

Referring to FIG. 4A, a semiconductor film 30 constituting an optical waveguide WG is disposed on a substrate 10. The optical waveguide WG may include a first slab portion SP1, a second slab portion SP2, and a lip portion RP disposed therebetween.

The first and second doping regions D1 and D2 may be formed in the first and second slab portions SP1 and SP2 and the vertical doping region (50) may be formed. According to this embodiment, the first and second doped regions D1 and D2 may be of a first conductivity type and the vertical doped region 50 may be of a second conductivity type different from the first conductivity type. For example, when the first and second doped regions D1 and D2 are p-type, the vertical doped region 50 may be n-type.

According to this embodiment, a part of the optical waveguide WG interposed between the first doped region D1 and the vertical doped region 50 (hereinafter referred to as a first body region B1) It can have properties close to that of a semiconductor (intrinsic semiconductor). For example, the first body region B1 may be undoped silicon or silicon having a doping level that is orders of magnitude lower than the first doped region D1. Accordingly, the first doped region D1, the first body region B1, and the vertical doped region 50 may form a PIN junction as shown in FIG. 4B. Similarly, another portion of the optical waveguide WG (hereinafter referred to as the second body region B2) sandwiched between the second doped region D2 and the vertical doped region 50 is substantially close to the intrinsic semiconductor By having physical properties, the second doped region D2, the second body region B2, and the vertical doped region 50 can also constitute a pi-yne junction.

In addition, the vertical doped region 50 may be formed such that its bottom surface contacts the upper surface of the buried insulating film 20. That is, the thickness of the vertical doped region 50 may be substantially equal to the thickness of the lip portion RP. In this case, as shown in the figure, the first body region B1 and the second body region B2 are separated from each other by the vertical doping region 50, These junctions can be formed. The vertical doped region 50 may be used as a common electrode of two piezane junctions defined by the first and second body regions B1 and B2.

4A is a cross-sectional view showing an electro-optic modulation element projected on one of the planes crossing the traveling direction of the optical waveguide WG, and the electro-optic modulation element according to the present invention is an optical waveguide It is not intended to be seen as having a structure as shown throughout. That is, the electro-optic modulation device according to the present invention includes a portion formed in the cross-sectional structure shown in the drawings, but not all portions of the electro-optic modulation device need to be formed with the cross-sectional structure shown. For example, in the portion not used as a modulation region of the optical waveguide WG, the vertical doping region 50 is formed such that the first body region B1 directly contacts the second body region B2, May not be formed.

According to this embodiment, the first and second doped regions D1 and D2 may be formed to have a bottom surface in contact with the upper surface of the embedded insulating film 20. [ That is, the thicknesses of the first and second doped regions D1 and D2 may be substantially the same as those of the first and second slab portions SP1 and SP2. 4B, although the abrupt junction structure is illustrated by way of example, the concentration profile of each part of the pi-ene junction can be variously modified and embodied from that shown.

The vertical doping region 50 is electrically connected to a first circuit C1 that generates a first voltage V1 using the first wiring structure 91 and the first and second doped regions D1 And D2 may be electrically connected to the second circuit C2 that generates the second voltage V2 using the second wiring structure 92a and 92b.

According to an embodiment, the first voltage V1 and the second voltage V2 may be a modulation voltage and a ground voltage, respectively. A predetermined potential difference depending on the first voltage V1 may be generated between the vertical doped region 50 and the first and second body portions B1 and B2. As described above, since both sidewalls of the vertical doped region 50 are all used to form the pi- ene junctions, the electro-optic modulation element according to the embodiment described with reference to Fig. , It is possible to cause an increase in the effective refractive index. This increase in the effective refractive index change makes it possible to obtain an increased phase shift or to make the length of the modulation region short in the optical waveguide. In particular, when the first and second voltages V1 and V2 are generated so that the piezane junctions operate in the forward mode of the piezane, the magnitude of the current injected into the optical waveguide is doubled Can be increased. In other words, the electro-optic modulation element according to this embodiment makes it possible to realize higher efficiency phase shift with a lower modulation voltage than in the prior art. In addition, when the width of the vertical doping region 50 is maintained at a predetermined size or less, the problem of light loss that can be caused by the heavily doped vertical doping region 50 can be suppressed.

[Third Variation example ]

5A is a cross-sectional view showing cross sections of electro-optic modulation elements according to a third modification of the present invention. FIG. 5B is a graph illustrating a forward-doping profile of an electro-optic modulation device according to a third modification of the present invention. FIG. Specifically, FIG. 5B is a graph showing the forward-doping profile along the dashed line I-I 'of FIG. 5A. For brevity of description, the description of the technical features overlapping with the embodiments described with reference to Figs. 4A and 4B can be omitted.

Referring to FIG. 5A, according to this embodiment, a vertical structure including two vertical doped regions 50 may be formed in the lip portion RP. In addition, the vertical structure may include a pair of intrinsic regions B33 and B34 interposed between the vertical doping regions 50 and an intrinsic doping region B33 interposed between the intrinsic regions B33 and B34 B35).

The intrinsic regions B33 and B34 may have physical properties similar to intrinsic semiconductors as the first and second body regions B1 and B2. However, it is not necessary that the intrinsic regions B33 and B34 and the first and second body regions B1 and B2 have completely the same physical properties.

The inner doped region B35 may have the same conductivity type as the first and second doped regions D1 and D2. That is, the inner doped region B35 has a different conductivity type from the vertical doped regions 50, and as shown in FIG. 5B, a pair of piezien junctions may be formed inside the vertical structure . As a result, the optical waveguide WG has four (4) pieces, each of which uses the first and second body regions B1 and B2 and the first and second intrinsic regions B33 and B34 as intrinsic semiconductors Pi] < / RTI > Thus, this embodiment can include pianeen junctions with increased lengths compared to the embodiment described with reference to Figure 4a.

5A, the vertical doped regions 50 are electrically connected to the first circuit C1 that generates the first voltage V1 using the first wiring structure 91, The internal doping region B35 can be electrically connected to the second circuit C2 that generates the second voltage V2 using the internal wiring structure 92c.

According to an embodiment, the first voltage V1 and the second voltage V2 may be a modulation voltage and a ground voltage, respectively. A predetermined potential difference depending on the first voltage V1 may be generated between the vertical doped region 50 and the first and second body portions B1 and B2. In particular, when the first and second voltages V1 and V2 are generated so that the piezane junctions operate in a forward mode of piezane, the magnitude of the current injected into the optical waveguide can be determined according to the prior art or with reference to FIG. 4A Can be further increased compared to the embodiment described. Similar to the previous embodiments, when the width of the vertical doped regions 50 is maintained to be equal to or less than a predetermined size, the light loss that can be caused by the heavily doped vertical doped regions 50 The problem can be suppressed.

[Fourth Variation example ]

6A and 6B are cross-sectional views showing cross sections of electro-optic modulation elements according to a fourth modification of the present invention. FIG. 6C is a graph illustrating a forward-doping profile of an electro-optic modulation device according to a fourth modification of the present invention. FIG. Specifically, FIG. 6C is a graph showing the forward-doping profile along the dashed line I-I 'of FIGS. 6A and 6B. For brevity of description, the description of the technical features overlapping with the embodiments described with reference to Figs. 4A and 4B can be omitted.

6A and 6B, according to this embodiment, the lip portion RP includes two vertical doping regions 50 and one inner doping region 50 interposed between the vertical doping regions 50 B35) may be formed.

The inner doped region B35 may have the same conductivity type as the first and second doped regions D1 and D2. That is, the inner doped region B35 has a different conductivity type from that of the vertical doped regions 50, and as shown in FIG. 6C, a pair of p-type junctions may be formed inside the vertical structure. As a result, the optical waveguide WG may include two pi-ene junctions and two pie junctions.

According to one embodiment, the vertical doped regions 50 are electrically connected to the first circuit C1 that generates the first voltage V1 using the first wiring structure 91, as shown in FIG. 6A And the internal doped region B35 may be electrically connected to the second circuit C2 that generates the second voltage V2 using the internal wiring structure 92c. According to this embodiment, a forward DC voltage is applied between the vertical doped regions 50 and the first and second doped regions D1 and D2 so that the PiAn junctions are PIN forward mode. In addition, a DC voltage in a reverse direction is applied between the vertical doped regions 50 and the inner doped region B35, so that the PN junctions can be operated in a PN reverse mode. As a result, the electro-optic modulation element according to this embodiment can be a hybrid structure, in which two effects together bring about a change in the refractive index. One of these effects is the change in refractive index according to the current injection effect of the two piezane junctions operating in the forward mode of piezane and the other is the change in the refractive index due to the depletion layer change in the two pie junctions operating in the pi & Change.

6B, the vertical doped regions 50 are electrically connected to the first circuit Cl generating the first voltage V1 using the first wiring structure 91. In other words, And the internal doped region B35 may be in a state where it is not electrically connected to the external circuit. According to this embodiment, a forward DC voltage is applied between the vertical doped regions 50 and the first and second doped regions D1 and D2 so that the PiAn junctions are PIN forward mode. However, the internal doped region B35 may be in an electrically floating state.

[Fifth Variation example ]

7A is a cross-sectional view showing cross sections of electro-optic modulation elements according to a fifth modification of the present invention. FIG. 7B is a graph illustrating a forward-doping profile of an electro-optic modulation device according to a fifth modification of the present invention. Specifically, FIG. 7B is a graph showing the forward-doping profile along the dashed line I-I 'of FIG. 7A. For brevity of description, the description of the technical features overlapping with the embodiments described with reference to the preceding drawings may be omitted.

Referring to FIG. 7A, according to this embodiment, the lip portion RP includes three vertical doping regions 50 and a pair of inner doping regions B36 interposed between the vertical doping regions 50 , B37) may be formed.

The internal doped regions B36 and B37 may have the same conductivity type as the first and second doped regions D1 and D2. That is, the inner doped regions B36 and B37 have different conductivity types from those of the vertical doped regions 50. As a result, as shown in FIG. 7B, four pn junctions are formed inside the vertical structure . As a result, the optical waveguide WG includes two piezienes junctions implemented using the first and second body regions B1 and B2 and four pien junctions implemented within the vertical structure .

The vertical doped regions 50 are electrically connected to the first circuit C1 that generates the first voltage V1 using the first wiring structure 91 as shown in Figure 7A, The doped regions B36 and B37 may be electrically connected to the second circuit C2 that generates the second voltage V2 using the internal wiring structure 92c. According to this embodiment, a forward DC voltage is applied between the vertical doped regions 50 and the first and second doped regions D1 and D2 so that the PiAn junctions are PIN forward mode. In addition, a DC voltage in a reverse direction is applied between the vertical doped regions 50 and the inner doped regions B36 and B37, so that the pn junctions can be operated in a PN reverse mode. As a result, the electro-optic modulation element according to this embodiment may also be one of the hybrid structures described with reference to FIG. 6A. That is, the electro-optic modulation device according to this embodiment has the effect of varying the refractive index according to the current injection effect in the two piezane joints operating in the forward mode of piezohene and the effect of the refractive index change in the four pien junctions operating in the Phen reverse mode The effect of changing the refractive index according to the depletion layer change can be simultaneously realized.

[Sixth Variation example ]

8A to 8C are cross-sectional views showing cross sections of electro-optic modulation elements according to a sixth modification of the present invention. Specifically, Figs. 8A to 8C relate to embodiments modified from the embodiments described with reference to Figs. 5A, 6A and 7A, respectively, and for the sake of brevity of description, Descriptions of the technical features overlapping with the examples may be omitted.

8A to 8C, internal doping regions (i.e., B35 in FIGS. 8A and 8B and B36 and B37 in FIG. 8C) within the vertical structure are connected to a third circuit C3. ≪ / RTI > In this case, the third voltage V3 may be different from the second voltage V2, which is a voltage applied to the first and second doped regions D1 and D2. Accordingly, the pi-ene junctions of Fig. 8a or the pien junctions of Figs. 8b and 8c formed inside the vertical structure can be operated independently of the pi-ene junctions formed outside the vertical structure.

Specifically, according to one embodiment, forward DC voltage is applied between the vertical doping regions 50 and the first and second doped regions D1 and D2, The pi-ene junctions may be operated in a PIN forward mode. However, since the potential difference applied between the vertical doped regions 50 and the inner doped regions B36 and B37 can be determined by the third voltage V3 different from the second voltage V2, The junctions within the vertical structure can be operated under optimized conditions regardless of the operation of the piezien junctions outside the vertical structure. As a result, the internal and external junctions of the vertical structure can be operated independently of each other under optimized conditions, and this independent optimization can be used to improve the modulation characteristics in the electro-optic modulation device according to this embodiment .

[Third Example ]

Figs. 9A and 9B are cross-sectional views showing cross sections of electro-optic modulation elements according to a third embodiment of the present invention. For brevity of description, the description of the technical features overlapping with the above-described embodiments may be omitted.

9A and 9B, a semiconductor film 30 constituting an optical waveguide WG is disposed on a substrate 10. In this case, The optical waveguide WG may include a first slab portion SP1, a second slab portion SP2, and a lip portion RP disposed therebetween.

First and second doped regions D1 and D2 may be formed in each of the first and second slab portions SP1 and SP2 and a vertical structure may be formed in the lip portion RP. According to this embodiment, the first doped region D1 and the second doped region D2 may have different conductivity types. For example, the first doped region D1 may be p-type and the second doped region D2 may be n-type. Accordingly, the first and second slab portions SP1, SP2 may be asymmetric in terms of the doping profile with respect to the lip portion RP.

The vertical structure may include a first vertical doped region 51 and a second vertical doped region 52 spaced from each other, and an inner region B3 interposed therebetween. The first vertical doping region 51 and the second vertical doping region 52 may have different conductivity types, and the inner region B3 may be an intrinsic semiconductor. Accordingly, the first vertical doped region 51, the second vertical doped region 52, and the inner region B3 formed inside the vertical structure can constitute one pi-ANjunction.

In addition, the first vertical doped region 51 is formed adjacent to the first doped region D1 while having a conductivity type different from that of the first doped region D1, and the second vertical doped region 52 May be formed adjacent to the second doped region D2 while having a conductivity type different from that of the second doped region D2. A first body region B1 disposed between the first vertical doped region 51 and the first doped region D1 and a second body region B1 disposed between the second vertical doped region 52 and the second doped region D2. The second body region B2 to be disposed may be an intrinsic semiconductor. In this case, the first vertical doped region 51, the first body region B1, and the first doped region D1 constitute one piano junction and the second vertical doped region 52, The second body region B2 and the second doped region D2 may constitute another piAnn junction.

The first and second vertical doped regions 51 and 52 may be formed to a depth shorter than the thickness of the lip portion RP as shown in FIG. To the upper surface.

The first vertical doping region 51 and the second doped region D2 are electrically connected to a first circuit C1 that generates a first voltage V1 using the first wiring structure 91, The second vertical doped region 52 and the first doped region D1 may be electrically connected to the second circuit C2 that generates the second voltage V2 using the second wiring structure 92 . According to an embodiment, the first voltage V1 and the second voltage V2 may be a modulation voltage and a ground voltage, respectively. In addition, the first and second circuits C1 and C2 may generate the first and second voltages V1 and V2 such that the piezane junctions operate in a forward mode.

[Fourth Example ]

10A and 10B are cross-sectional views showing cross-sections of electro-optic modulation elements according to a fourth embodiment of the present invention. For brevity of description, the description of the technical features overlapping with the above-described embodiments may be omitted.

Referring to FIGS. 10A and 10B, a semiconductor film 30 constituting an optical waveguide WG is disposed on a substrate 10. The optical waveguide WG may be formed to have sidewalls exposing the upper surface of the embedded insulating film 20. [ That is, according to this embodiment, the optical waveguide WG may be formed in a channel waveguide structure.

A vertical structure having at least one pair of vertical doped regions 50 may be formed in the optical waveguide WG. The vertical structure includes an inner doped region B35 interposed between the vertical doped regions 50 and at least two inner regions interposed between the inner doped region B35 and the vertical doped regions 50 B36, B37). The inner doped region B35 may have a different conductivity type from the vertical doped regions 50. [ The inner regions B36 and B37 may be doped with a predetermined impurity as shown in FIG. 10A or may be an intrinsic semiconductor as shown in FIG. 10B.

In the case where the internal regions B36 and B37 are doped, the internal regions B36 and B37 are lower than the internal doping region B35 at the impurity concentration, And may be the same as the internal doping region B35. According to this embodiment, the inner regions B36 and B37 and the vertical doping regions 50 may constitute a pair of pien junctions. According to a modified embodiment, the inner regions B36 and B37 may be lower than the vertical doping region 50 at an impurity concentration and may be the same as the vertical doping region 50 in a conductive type. Likewise, according to this modified embodiment, the inner regions B36 and B37 and the inner doped region B35 can constitute a pair of pien junctions.

10B, the vertical doping regions 50, the inner regions B36 and B37, and the inner doping region B35 may be formed of the same material as the inner regions B36 and B37, Lt; RTI ID = 0.0 > pi < / RTI >

The vertical doped regions 50 are electrically connected to a first circuit C1 that generates a first voltage V1 using a first wiring structure 91 and the inner doped region B35 is electrically connected to a second And may be electrically connected to the second circuit C2 that generates the second voltage V2 using the wiring structure 92. [ The first voltage V1 and the second voltage V2 may be a modulation voltage and a ground voltage, respectively. In the case of the embodiment described with reference to FIG. 10A, the first and second circuits C1 and C2 generate the first and second voltages V1 and V2 so that the pn junctions operate in a Pn reverse mode, can do. 10b, the first and second circuits C1 and C2 are connected in series between the first and second voltages V1 and V2 to allow the piezane junctions to operate in a forward mode, Can be generated.

11 is a block diagram schematically illustrating an embodiment of an optical system including an optical transmitter and an optical receiver according to embodiments of the present invention.

Referring to FIG. 11, an optical system 1001 includes at least one optical transmitter 1002 and at least one optical receiver 1006. The optical system 1001 may include an optical device 1004 optically coupled between the optical transmitter 1002 and the optical receiver 1006. The optical transmitter 1002 may be configured to transmit an optical beam 1010, which is received at the optical device 1004. The optical device 1004 may be configured to modulate one of the optical properties of the optical beam 1010 in response to a modulating signal V1. For example, the optical device 1004 may include one of the electro-optic modulation elements described with reference to FIGS. According to one embodiment, the optical device 1004 may be configured to function as an optical delay. According to another embodiment, the optical device 1004 may be used to implement an optical amplitude modulator or the like.

FIG. 12 is a diagram illustrating an embodiment of an optical modulator 1100 that may be employed as the optical device 1004 of FIG.

12, the optical modulator 1100 includes two arms optically coupled between two cascaded Y-branch couplers of a Mach-Zehnder interferometer configuration (MZI) and an optical phase shifter 1110 formed on one of the arms. According to one embodiment, the optical phase shifter 1110 may be configured to have one of the electro-optic modulators described with reference to FIGS. 1-10, or a similar structure.

In operation, the optical beam 1010 is incident on the input portion of the MZI and then separated from the first Y-branch coupler. As a result, the first portion of the optical beam 1010 proceeds to one of the arms of the MZI and the second portion of the optical beam 1010 proceeds to the other of the arms of the MZI. As shown, the optical phase shifter 1110 is formed in one of the arms of the MZI such that the relative position between the first and second portions of the optical beam 1010, in response to the external signals V1 and V2, Adjust a relative phase difference. The first and second portions of the optical beam 1010 are combined at the output portion of the MZI. As a result of the constructive interference or extinction interference between the first and second portions of the optical beam 1010 due to the relative phase difference, the optical beam 1010 emitted from the output portion of the MZI has modulated properties . According to one embodiment, the optical beam 1010 incident on the input portion of the MZI may be a continuous wave, and the optical beam 1010 emitted from the output portion of the MZI may be reflected as a result of the modulation It may have a sawtooth waveform. According to a modified embodiment of the present invention, both arms of the MZI can be configured to include the electro-optic modulator disclosed by the present invention.

Meanwhile, the optical device 1004 may not be implemented only in the Mach-Zehnder interferometer structure, but may be implemented in various other ways. For example, the optical device 1004 may be implemented through a ring-resonator structure including one of the electro-optic modulators described with reference to FIGS. 1-10, or a similar structure.

According to an aspect of the present invention, the optical waveguide described with reference to FIGS. 1 to 10 may be implemented using an SOI wafer. According to another aspect of the present invention, the optical waveguide described with reference to FIGS. 1 to 10 may be implemented using an SOI wafer formed by implanting ions into a predetermined region of a silicon wafer. According to one embodiment, the ions may include oxygen atoms and may be injected locally at a predetermined position where the optical waveguide is to be formed.

Claims (26)

And an optical waveguide formed with a vertical structure having at least two side walls, wherein the side walls of the vertical structure are used to form a junction,
Wherein the optical waveguide has a slab waveguide structure including a first slab portion, a second slab portion and a rib portion interposed between the first and second slab portions, And the vertical structure is formed in the lip portion,
The optical waveguide includes:
A first body region extending from the first slab portion and contacting a side wall of the vertical structure; And
And a second body region extending from the second slab portion and contacting the other side wall of the vertical structure,
Wherein the first and second body regions are of a first conductivity type and the vertical structure comprises at least one vertical doped region having a second conductivity type different from the first conductivity type, . The method according to claim 1,
Wherein the optical waveguide is a channel waveguide structure formed to have a side wall exposing an upper surface of the buried insulating film, wherein the optical waveguide is disposed under the optical waveguide. delete delete The method according to claim 1,
Wherein the vertical length of the vertical structure is equal to the thickness of the lip portion and the first and second body regions are separated by the vertical structure. The method according to claim 1,
A first wiring structure electrically connecting the vertical doped region and the first circuit; And
And a second wiring structure electrically connecting the slab portion and the second circuit,
Wherein the first and second circuits are configured to generate a potential difference for reverse-biasing operation of a pair of pien junctions between the first and second body regions and the vertical structure, . The method according to claim 1,
Wherein the first slab portion comprises a first doped region of the first conductivity type,
The second slab portion including a second doped region of the first conductivity type,
The optical waveguide
A first body region extending from the first doped region and in contact with a side wall of the vertical structure; And
And a second body region extending from the second doped region and in contact with another side wall of the vertical structure,
Wherein the first and second body regions are formed of intrinsic semiconductors. The method of claim 7,
Wherein the first doped region, the first body region, and the vertical structure form a pi-junction,
Wherein the second doped region, the second body region, and the vertical structure form a pi-ene junction. The method of claim 8,
A first wiring structure electrically connecting the vertical doped region and the first circuit; And
And a second wiring structure electrically connecting the slab portion and the second circuit,
Wherein the first and second circuits are configured to generate a potential difference for net-bias operation of the pi-ene junctions. delete The method according to claim 1,
The vertical structure
A plurality of vertical doped regions; And
And at least one inner region interposed between the vertical doped regions. The method of claim 11,
Wherein the at least one inner region comprises an inner doping region having a conductivity type different from that of the vertical doping regions to form a PN junction with the vertical doping regions. . The method of claim 11,
Wherein the at least one inner region includes a pair of intrinsic regions and an inner doped region interposed between the intrinsic regions and having a conductivity type different from that of the vertical doped regions, (PIN-junction). ≪ RTI ID = 0.0 > [0002] < / RTI > The method of claim 11,
Wherein the first and second slab portions comprise first and second doped regions of the first conductivity type, respectively,
Wherein the internal region and the first and second doped regions are electrically connected to circuits generating different voltages. And an optical waveguide formed with a vertical structure having at least two side walls, wherein the side walls of the vertical structure are used to form a junction,
Wherein the optical waveguide has a slab waveguide structure including a first slab portion, a second slab portion and a rib portion interposed between the first and second slab portions, And the vertical structure is formed in the lip portion,
The optical waveguide includes:
A first body region extending from the first slab portion and contacting a side wall of the vertical structure; And
And a second body region extending from the second slab portion and contacting the other side wall of the vertical structure,
Wherein the first and second body regions are of a first conductivity type and the vertical structure comprises at least one vertical doped region having a second conductivity type different from the first conductivity type,
Wherein the first and second doped regions are electrically connected to each other under the lower wall of the vertical structure and are in an equipotential state. delete 16. The method of claim 15,
Wherein the first slab portion comprises a first doped region of the first conductivity type,
The second slab portion including a second doped region of the first conductivity type,
The optical waveguide
A first body region extending from the first doped region and in contact with a side wall of the vertical structure; And
And a second body region extending from the second doped region and in contact with another side wall of the vertical structure,
Wherein the first and second body regions are formed of intrinsic semiconductors. delete 16. The method of claim 15,
The lip portion includes a vertical structure having a pair of sidewalls and a bottom wall forming a PN junction,
The optical waveguide includes the first body region interposed between the first slab portion and the vertical structure and the second body region interposed between the second slab portion and the vertical structure Characterized in that the electro-optic modulation element. delete delete 16. The method of claim 15,
Wherein the vertical length of the vertical structure is smaller than the thickness of the lip portion and the first and second body regions are connected to each other below the vertical structure. 16. The method of claim 15,
A first wiring structure electrically connecting the vertical structure and the first circuit; And
And a second wiring structure electrically connecting the first and second slab portions to the second circuit,
Wherein the first and second circuits are configured to generate a potential difference for reverse-biasing operation of a pair of pien junctions between the first and second body regions and the vertical structure, . 18. The method of claim 17,
The lip portion includes a vertical structure that constitutes at least two PIN junctions,
Wherein the first and second slab portions each include first and second doped regions of the first conductivity type, the optical waveguide includes the first body region and the second body region interposed between the first slab portion and the vertical structure, And a second body region interposed between the second slab portion and the vertical structure,
Wherein the first and second body regions are intrinsic semiconductors. delete 27. The method of claim 24,
A first wiring structure electrically connecting the vertical structure and the first circuit; And
And a second wiring structure electrically connecting the first and second slab portions to the second circuit,
Wherein the first and second circuits are configured to generate a potential difference for net-bias operation of the pi-ene junctions.

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