JPH042177A - Lateral photodetector - Google Patents

Abstract

PURPOSE:To improve responding characteristic and to realize a wide band by providing an epitaxially grown layer having a wide band gap formed on the other side surface of a first conductivity type light absorption layer, and a Schottky electrode formed by separately on the grown layer in a direction crossing an incident light. CONSTITUTION:A lateral photodetector is formed of a p-type InP layer (second conductivity type semiconductor layer) 6 on a high resistance substrate made of InP, etc. Ao n-type GaInAs layer (first conductivity type light absorption layer) 7 is formed as a light absorption layer on the top of the layer 6. An epitaxially grown layer 8 is formed on the top of the layer 7. The layer 8 is formed of a material having a wide band gap such as an AlInAs. Further, a pair of Schottky electrodes 9, 10 are formed on the top of the layer 8. According to this configuration, installation region of the electrodes 9, 10 connected to negative bias voltage terminal is depleted by the operation of the layer 8 formed on the layer 7, and the electric field is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a horizontal light-receiving element in which a signal current flows in a direction substantially perpendicular to the direction of incidence of light.

[Conventional technology]

FIG. 3 shows a horizontal light receiving element according to the prior art. FIG. 5(a) shows a longitudinal cross-sectional view taken in the direction of incidence of light, and FIG. 2(b) shows its equivalent circuit. This photodetector is made of p-type In on a high-resistance 1nP substrate 1.
A P layer 2 is formed, and an undoped n-type GaInAs layer 3 is formed thereon as a light absorption layer. This n-type Ga1
A pair of n-type ohmic electrodes 4 are formed on the nAs layer 3 . In this horizontal photodetector, the p-type InP layer 2
is connected to the light absorption layer, the region below the electrode (left electrode) 4 to which a positive voltage is applied by the diode D1 is depleted. Therefore, among the electrons and holes generated by the incident light, the holes with a slow moving speed are transferred to the p-n junction.
It is absorbed by the type 1nP layer 2, and a wide band is achieved.

[Problem to be solved by the invention]

However, as shown in FIG. 3(b), the conventional horizontal photodetector has a drawback in that the diode D2 is biased in the forward direction, and the electric field in this portion becomes weak.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a horizontal light-receiving element that can solve the above-mentioned drawbacks.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a light absorption layer of a first conductivity type (e.g. n-type) in which carriers are generated by incident light, and a light absorption layer of a second conductivity type (e.g. p-type) bonded to one surface of the light absorption layer.
a horizontal light-receiving element comprising a semiconductor layer, an epitaxial growth layer with a wide bandgap formed on the other surface of the first conductivity type light absorption layer; The device is characterized in that it includes at least a pair of Schottky electrodes that are spaced apart from each other.

[Effect]

Since the present invention is configured as described above, the area where the Schottky electrode is connected to the negative terminal of the bias voltage is depleted due to the action of the epitaxial growth layer formed on the light absorption layer, and the electric field increases. .

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS A horizontal light receiving element according to an embodiment of the present invention will be described below with reference to the accompanying drawings. In the description, the same elements are denoted by the same reference numerals, and redundant description will be omitted.

FIG. 1(a) is a vertical cross-sectional view showing a horizontal light receiving element according to an example. In this horizontal light receiving element, a p-type 1nP layer (second conductivity type semiconductor layer) 6 is formed on a substrate 5 made of high resistance InP or the like. As a material, Ga is used instead of InP.
InAs may also be used. On top of this p-type InP layer 6, an n-type GaInAs layer (first
A conductive light absorption layer) 7 is formed. This n-type GaI
An epitaxial growth layer 8 is formed on the nAs layer 7 . This epitaxial growth layer 8 is made of a material with a wide gap, such as AlInAs. Furthermore, a pair of Schottky electrodes 9 and 10 are formed on the top of the epitaxial growth layer 8. The Schottky electrode 9.10 can be made of Ti/Pt/Au, for example.

FIG. 5B shows an equivalent circuit of the horizontal light-receiving element shown in FIG. According to this horizontal light-receiving element, four diodes D-D SDs and D6 are equivalently present. Among them, the diodes D3 and DB act as a reverse bias when a voltage is applied, so that not only the region below the Schottky electrode 9 but also the region below the Schottky electrode 10 is depleted, improving response characteristics.

FIG. 2 is a graph showing the results of an experiment comparing the response characteristics of the conventional horizontal light receiving element and the horizontal light receiving element according to the above embodiment. FIG. 5A shows the response characteristics of a conventional horizontal light receiving element, and FIG. As a light source, the wavelength is 1.3μm1
A light pulse with a half width of 40 pSee was used. Further, the bias voltage was 2V, and the electrode spacing was 5 μm.

According to the experimental results, the fall time was 600 psec in the conventional horizontal photodetector, but it was only 80 psec in the horizontal photodetector according to the example, indicating that the response characteristics were further improved.

Note that this invention is not limited to the above embodiments. For example, in the above embodiment, the first conductivity type is n type, and the second conductivity type is n type.
Although p-type is used as the conductivity type, p-type may be used as the first conductivity type, and n-type may be used as the second conductivity type.

Furthermore, the material, shape, number, arrangement example, etc. of the light absorption layer, epitaxial growth layer, and Schottky electrode are not limited to the above-mentioned examples, but may be appropriate depending on the usage conditions of the horizontal light receiving element. etc. are selected.

〔Effect of the invention〕

Since this invention is configured as explained above,
Compared to conventional horizontal photodetectors, the response characteristics are improved and a wider band can be achieved.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view showing a horizontal photodetector according to an embodiment of the present invention, and FIG. 2 is a graph showing experimental results comparing the response characteristics of a conventional horizontal photodetector and a horizontal photodetector according to the above embodiment. , FIG. 3 is a longitudinal sectional view showing a horizontal light receiving element according to the prior art. 1... InP substrate, 2... p-type InP layer, 3...
n-type Ga I nAs layer, 4... n-type ohmic electrode, 5... substrate, 6... p-type 1nP layer (second conductivity type semiconductor layer), 7... n-type Ga I nAs layer ( first conductivity type light absorption Jl), 8... epitaxial growth layer, 9
．． 10... Schottky electrode.

Claims (1)

[Claims] A horizontal light-receiving element comprising a first conductivity type light absorption layer in which carriers are generated by incident light and a second conductivity type semiconductor layer bonded to one surface of the light absorption layer, the first conductivity type light absorption layer It is configured to include an epitaxial growth layer with a wide bandgap formed on the other surface, and at least a pair of Schottky electrodes provided on the epitaxial growth layer in a direction intersecting the incident light and spaced apart from each other. Characteristic horizontal light-receiving element.