JPS6237553B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light receiving and emitting method and apparatus, and more particularly to a light receiving and emitting method and apparatus that use a semiconductor and are capable of erasable optical writing and optical reading.

When processing optical information, it is necessary to detect the given optical information and output a corresponding signal. From the perspective of information processing, it is desirable to use electrical signals, and when storing optical information, the optical information is converted into electrical information, then stored on a storage medium, and when read out, the method is to read out the information as an electrical signal. It is. Therefore, when optical information that has been stored once is to be displayed or transferred to another storage medium, except in the case of photographic film, the stored information must be converted into a series of electrical signals and then transferred to a display device or transferred. The information was transferred sequentially to a storage medium. Such a method has the disadvantage that not only the device becomes complicated but also signal processing requires a lot of time. Although photographic film has the advantage of being easy to transfer and display, it has the disadvantage that it cannot be erased and reused, and that electrical signal processing is complicated.

An object of the present invention is to provide a light receiving and emitting method and apparatus that can store optical information as an electrical signal and output it as optical information.

Another object of the present invention is to provide a method and device for receiving and emitting light that can store optical information electrically and read it out as electrical or optical information.

It is well known that semiconductors can be used as light receiving devices, and photodiodes, phototransistors, CCD photosensors, and the like are commercially available or have been announced. Furthermore, if the control region of a unipolar transistor is made into an accumulation region of photoionized carriers, a highly sensitive phototransistor can be formed (Japanese Patent Application No. 1986-86572 ``Semiconductor Photoelectric Conversion Device'').

Furthermore, it is well known that semiconductors can be used as light emitting devices, such as semiconductor light emitting diodes and semiconductor lasers.

The concept of the present invention is to integrate a semiconductor light-receiving element and a semiconductor light-emitting element into a single chip and to effectively receive and emit light. By supplying the received optical information as a corresponding optical output, optical information can be transferred and copied in a short time.

When a unipolar transistor structure is used as a semiconductor light-receiving element, optical information can be accumulated (integrated and stored), and it can be used as a dynamic optical memory, and electrical and optical signals corresponding to the memory can be obtained. Since optical signals can be easily transmitted simultaneously and in parallel, signal transfer can be performed in an extremely short time.

Further, since the light receiving/emitting device of the present invention can have a light amplifying effect, it is effective as a relay for an optical transmission line.

As an application example, when the present invention is used in a facsimile together with an image transmission optical fiber,
It is expected that the time required for image transmission will be dramatically reduced.

Furthermore, as another example of application, when the present invention is used in the memory section of an electronic computer, it can be expected that the time required for memory transfer will be dramatically reduced.

Embodiments of the present invention will be described below with reference to the drawings.

Figures 1a, b, and c show simplified embodiments for explaining the basic principle of the present invention, in which a is a cross-sectional view, b is a plan view of the buried storage region, and c is a buried main electrode. FIG. 3 is a plan view of the area. Dimensions in the drawings have been arbitrarily changed for illustrative purposes, and the shapes are not exact.

An n ⁻ type region 2 is arranged on the n ⁺ type region 1, and a p ⁺ type storage region 3 is embedded in the n ⁻ type region 2.
This p ⁺ type storage region 3 has a large number of storage segment regions 311, 312, . . . as shown in FIG. 1b.
321, 322, . . . and each segment is separated in the n ^- type region 2. n ^- type region 2
Segment regions ⁴¹¹ , 412, . . . , 421, 422, as shown in FIG.
An n ⁺ type main electrode region 4 consisting of... is arranged, and n ^-
A p-type region 5 is arranged on the entire upper surface of the type region 2. On the surfaces of the n ⁺ type region 1 and the p type region 5, electrodes 1' and 5' with windows are formed at locations corresponding to the respective segments.

When light enters from the bottom surface in the figure and generates pairs (electron-hole pairs) in the n ⁻ type region 2 , holes among the generated carriers are accumulated in the p ⁺ type accumulation region 3 . Since a potential gradient due to the diffusion potential is formed between each storage segment region and the n ^- type region 2, pairs generated at a location where this potential gradient exists move according to the potential gradient, and each segment region accumulates a charge corresponding to the amount of light incident near that area. That is, the storage segment area 311,3
12, . . . , 321, 322, .

Next, when a forward voltage is applied between electrodes 1' and 5', that is, a negative voltage to electrode 1' or a positive voltage to electrode 5', n ⁺ type region 1 to n ⁺ type region 4 are applied within each segment.
Electrons according to the potential of the storage region 3 flow toward
The electron flow further flows into the p-type region 5 and recombines with the holes to generate light hv. In this way, each segment area emits light according to the amount of light incident thereon. In other words, in the light receiving process, areas 1, 2, 3, 4
works as a unipolar photodiode,
In the light emitting process, the n ⁺ type main electrode region 4 and the p type region 5 function as a light emitting diode. The n ⁺ type main electrode region 4 has a large number of segment regions 411, 412,...
It consists of ..., 421, 422, ..., so
A large number of light emitting diodes emit light according to the amount of incident light. Unipolar phototransistors can have saturated or unsaturated characteristics by controlling the impurity density and dimensions of the channel region.
If it has unsaturated characteristics, the current can be controlled by the applied voltage.

In one example of this embodiment, the light emitting active region 5 is formed of an epitaxial layer of GaP, and the other regions 1, 2, 3, 4 are formed of a GaP epitaxial layer.
is made of Si. A low-resistance p ⁺ -type region 3 serving as a buried region is formed on a high-resistance n ^- -type Si substrate, and a high-resistance n ⁺ -type region is further formed thereon. An n ⁺ -type region is formed on the entire surface of one surface of the Si chip thus formed and on a required portion of the other surface by diffusion, ion implantation, or the like.

In another example, all semiconductor regions are formed of GaAS. When forming a light-receiving element with a direct transition semiconductor such as GaAs, care must be taken to ensure that the accumulation region is not too far away from the incident surface.

When the light receiving element is made of Si light emitting element and made of GaAs, wavelength compatibility is excellent. From the viewpoint of manufacturing, it is important to match the lattice constants, and it is preferable that the light emitting element and the light receiving element be made of the same semiconductor material or of semiconductors with similar lattice constants.

Light reception and light emission are mediated by electrical signals (light-electricity-
It is also possible to convert the wavelengths of incident light and emitted light. For example, if GaAs is used as the light-receiving element and InGaP is used as the light-emitting element, infrared light can be converted to visible light. Similarly, to convert long wavelength light into visible light, use a semiconductor with a narrow bandgap such as HgCdTe, PbSnTe, etc. as the light receiving element, and use a semiconductor with a wide bandgap that emits visible light as the light emitting element. good.

If the lattice constants cannot be matched using only two types of semiconductors, an additional layer may be provided for lattice constant matching.

For example, HgCdTe-based mixed crystals have a very small change in lattice constant, but the forbidden band changes from infrared to far infrared, so the lattice constant is relatively close to this.
Infrared light and
Visible light conversion can be performed.

Examples of changes to the structure shown in Figure 1 are shown in Figure 2 a, b,
Shown in c. Although only a top view of the storage region is shown in these figures, other parts will be easily understood from FIG. In these structures, the storage region of one light-receiving element is formed by a plurality of segments, and each segment serves as a common storage region for two light-receiving elements located on both sides thereof. In FIG. 2a, each light receiving element has a triangular shape, in FIG. 2b, each light receiving element has a square shape as in FIG. 1, and in FIG. 2c, each light receiving element has a hexagonal shape. In addition, any rectangular or diamond shaped elements may be used as long as they have the same shape and can be arranged periodically.

The structure shown in FIG. 2, in which one storage segment is commonly used by a plurality of light receiving elements, has the advantage that the light receiving area can be used without waste and the degree of integration can be increased.

Once light reception storage is performed, a certain length of time or more is required to perform the next light reception storage. Furthermore, in the light receiving/emitting device having the structure described above, all the elements emit light at the same time, so it is not possible to randomly access each element or electrically read out the memory of each element.

An embodiment that improves these drawbacks will be described below.

FIGS. 3a and 3b show an embodiment in which the memory can be actively cleared and each element can be selectively read out electrically and optically. The same reference symbols indicate similar parts throughout the drawings.

FIG. 3a is an equivalent circuit of a light receiving and emitting device in which picture elements are arranged in a two-dimensional array, and FIG. 3b is a partial sectional view.

In FIG. 3a, column lines a1, a2, a3,...
... and row lines b1, b2, b3, ... intersect with each other, and at each intersection, picture elements PE11, PE12, ...PE2
1, PE22, . . . are arranged. Each picture element
PEij includes a series connection of a light emitting diode Dij connected to the column line ai and a nipolar phototransistor Qij connected to the row line bj. Furthermore, an insulated electrode for controlling the potential of the storage region of the phototransistor Qij is connected to the corresponding ci of the clear lines c1, c2, . . . arranged in parallel with the column lines a1, a2, . The column line control circuit 21 controls the column lines a1, a2, a
3,... supplies a control signal to the row line control circuit 22
supplies control signals to the row lines b1, b2, b3, . Similarly, the clear line control circuit 23 supplies control signals to the clear lines c1, c2, c3, .
Row lines b1, b2, b3, ... and column lines a1, a2,
If a forward voltage is applied at once between a3, . Row line b1,
Keep b2, b3, ... at zero potential and clear wire c
When a positive voltage is applied to 1, c2, and c3, the charges accumulated in the accumulation regions of each picture element disappear at the same time. If you want to read any picture element PEij, select the corresponding row line.
If a forward voltage is applied between bi and column line aj, a current will flow at the same time as the light emitting diode emits light. The amount of light emission and the current value correspond to each other, and both represent the amount of accumulated charge. In order to clear any picture element, a clear voltage may be similarly applied between the corresponding clear line and the row line. It is obvious that if individual clearing is not necessary, all the clearing lines may be made common.

The structure shown in FIG. 3b is basically the same as the structure shown in FIG.
A clear electrode 3' is provided via the clear electrode 3'. Further, on the light emitting active region 5, corresponding to each segment,
A row of p ⁺ type regions 9 is provided, and an electrode 5' is formed thereon. 10 is an opaque insulating resin. The electrodes 3' and 5' extend in a direction perpendicular to the plane of the paper and form clear lines and column lines. Electrode 1'
At least a portion above the light receiving window is preferably made of a transparent electrode such as SnO2 or polycrystalline silicon.

FIG. 4 shows an embodiment using an insulated gate type light receiving element. The basic configuration is the same as the embodiment shown in FIG. 3, but there is no semiconductor storage region 3 of the opposite conductivity type, and a potential well is formed with an insulated gate structure, and the control electrode 3, which is also a clear electrode, is connected to each other. It has become common across segments. Furthermore, each light emitting area 5 is separated by an opaque insulating resin 10. It has the advantages of simple structure, easy manufacture, and individual readout.

Although the embodiment in which a unipolar type semiconductor element is used as the light receiving element has been shown above, the light receiving element can also be made of a bipolar type phototransistor as in the embodiment shown in FIG.

In FIG. 5, the n ⁺ type region 11 is an emitter, p
Type region 12 is the base, n ^- type region 13, n ⁺ region 1
A collector 4 forms a bipolar phototransistor together with the emitter electrode 18. P type region 15 forms a light emitting diode with n ⁺ type region 14. The p ⁺ type region 16 is a dot-shaped low resistance region provided on each segment, surrounded by an opaque insulating resin region 17, and in ohmic contact with the electrode 19.

Figure 6 shows an example of a combination of a pin avalanche photodiode and a light emitting diode.
The p-type region 31, the i-type region 32, and the n-type region 33 form a photodiode, and the p-type region 34 and the p ⁺
Type region 35 and n-type region 33 form a light emitting diode. Opaque insulating resin 37, 38 provides separation between each segment. 36 and 39 are electrodes. When a high positive voltage is applied to the electrode 39, a forward voltage is applied to the light emitting diode and a reverse voltage is applied to the light receiving diode. Carriers ionized by light in the i-region 32 cause an avalanche, causing carrier multiplication of about 100 to 10,000 times. This carrier current causes light emission through the light emitting diode.

Although the present invention has been described above in accordance with the embodiments, the present invention is not limited to the above embodiments, and various changes and modifications may be made.
It is obvious that combinations etc. are possible. In order to improve the directivity of light emission, a lens structure may be formed on the light emitting surface, or other circuits may be incorporated into the same semiconductor chip.

The gist of the present invention is to integrate a light-receiving element and a light-emitting element and use them in conjunction with each other, so that light-to-light conversion can be performed in a short time. According to one embodiment of the present invention, an optical-to-optical and optical-to-electrical conversion device having a memory function is provided, and by arranging a light receiving and emitting device and an optical storage device and performing optical reading, a large number of states can be recorded. Simultaneous transfer can be performed, and the light receiving/emitting device can be used as a normal optical memory. In addition, the present invention has a very wide range of applications in the field of optoelectronics and is of high industrial value.

[Brief explanation of the drawing]

FIGS. 1a, b, and c are a cross-sectional view, a top view of the storage region, and a top view of the buried main electrode region of one embodiment of the present invention, and FIGS. 2a, b, and c are other views of the storage region. FIG. 3 is a top view showing the shape; FIGS. 3a and 3b are an equivalent circuit diagram and a partial sectional view of another embodiment of the present invention;
6 through 6 are partial cross-sectional views of other embodiments of the present invention.

Claims (1)

[Scope of Claims] 1. Light is incident on a semiconductor light-receiving element formed by a unipolar phototransistor having unsaturated current-voltage characteristics to change the effective internal impedance, and the effective internal impedance is changed through the semiconductor light-receiving element. A light-receiving and light-emitting method characterized in that a current is introduced into a photoactive semiconductor region integrated in a semiconductor substrate through a pn junction made of the same semiconductor as a semiconductor light-receiving element or a heterojunction made of a different type of semiconductor to cause light emission. 2. Injecting light into the vicinity of the pn junction formed between the control region and the channel region of the semiconductor light receiving element,
accumulating one polarity of ionized carriers in one of the two semiconductor regions forming the p-n junction, wherein the emitted light transfers minority carriers through the other of the two semiconductor regions to the photoactive semiconductor region. The method of receiving and emitting light according to claim 1, characterized in that the method includes injection. 3. A semiconductor light-receiving element formed by a unipolar phototransistor that can change the effective internal impedance in response to incident light and has unsaturated current-voltage characteristics and a semiconductor light-emitting element are formed of the same semiconductor. A semiconductor light-receiving and light-emitting device including, in a single semiconductor chip, at least one semiconductor light-receiving and light-emitting picture element connected in series in a semiconductor substrate via a pn junction or a heterojunction made of an abnormal semiconductor, the semiconductor light-receiving element and the semiconductor The semiconductor light receiving element substantially surrounds a current path region of one conductivity type and the current path region, and accumulates ionized carriers to electrically conduct the current path region. an accumulation control region to control the accumulation control region, the semiconductor light receiving element further includes clearing means for clearing charges accumulated in the accumulation control region, the clearing means includes an insulated gate electrode structure, and the accumulation control region is formed of a semiconductor region of the other conductivity type, and the clearing means includes a capacitor structure between the storage control region and the storage control region. 4 In the heterojunction made of the dissimilar semiconductor,
Claim 3 characterized in that an additional layer for lattice constant adaptation is provided at the heterojunction interface.
The semiconductor light-receiving and light-emitting device described in 1. 5. The semiconductor light receiving element is formed of silicon,
4. A semiconductor light-receiving and light-emitting device according to claim 3, wherein said semiconductor light-receiving element is made of gallium phosphorus. 6. The number of the semiconductor light-receiving and light-emitting picture elements is plural,
Claim 3, wherein a plurality of semiconductor light-receiving and light-emitting picture elements are arranged at predetermined positions within the single semiconductor chip and can receive light in an optical pattern and emit corresponding light. Semiconductor light receiving and emitting device. 7. The semiconductor light-receiving and light-emitting device according to claim 6, wherein the plurality of semiconductor light-receiving and light-emitting picture elements are arranged in a two-dimensional array. 8. The array has a row line and a column line connected to the array, and the semiconductor light receiving element is connected to the row line and the semiconductor light receiving element is connected to the column line. Semiconductor light receiving and emitting device.