JP2955286B1 - Semiconductor photoelectric conversion element - Google Patents

Abstract

An object of the present invention is to provide a semiconductor photoelectric conversion element which can be connected to another element on a flat substrate and can operate at a higher speed than a conventional example. SOLUTION: A first flat portion 10a and a second flat portion 10 are provided.
c on a semiconductor substrate 10 having a slope 10b,
Photoconductive layer 1 sandwiched between a pair of barrier layers 11 and 13
2 is formed, the contact semiconductor layers 14a, 14b, and 14c are formed on the photoconductive layer 12 in the first direction due to a difference in plane orientation.
Of the contact semiconductor layer 14a on the flat portion 10a becomes p-type, and the contact semiconductor layer 1a on the slope portion 10b becomes p-type.
By forming the conduction type of 4b to be n-type,
A horizontal pin junction including the i-type photoconductive layer 12 is formed. The light is received and absorbed by the photoconductive layer 12,
The photoelectric conversion is performed by the current flowing through the pin junction in the lateral direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a semiconductor photoelectric conversion element.

[0002]

2. Description of the Related Art The demand for semiconductor photoelectric conversion elements or light-receiving elements used in magneto-optical storage devices, home video cameras, digital cameras, faxes, scanners, etc. has been rapidly increasing even in general homes. Is shown. In addition, circuits that combine optical circuits and electrical circuits will be
Applications are expected in various fields, and the photoelectric conversion element is a key part in such devices.

[0003]

In recent years, in the field of optical communication, higher-speed and larger-capacity communication has been demanded, and high-speed photoelectric conversion has also been demanded in light-receiving elements. In the field of optical communication, optical connection between elements is an important theme, and connection with other elements such as a semiconductor laser device, an optical isolator, and an optical fiber cable as a light source is conventionally performed by a method called active alignment. Although it has been recently attempted to solve the problem by positioning and mounting each element on a flat substrate, there has been a problem that it is extremely difficult to complete many elements only by positioning.

[0004] An object of the present invention is to solve the above problems,
It is an object of the present invention to provide a semiconductor photoelectric conversion element which can be connected to another element on a flat substrate and can operate at a higher speed than a conventional example.

[0005]

According to a first aspect of the present invention, there is provided a semiconductor photoelectric conversion device comprising a pair of semiconductor photoelectric conversion elements on a semiconductor substrate having a slope portion between a first flat portion and a second flat portion. After forming the photoconductive layer sandwiched by the barrier layer, a contact semiconductor layer on the photoconductive layer, due to the difference in plane orientation,
By forming the contact semiconductor layer on the first flat portion to be p-type and the contact semiconductor layer on the slope portion to be n-type, a lateral direction including the i-type photoconductive layer is formed. Wherein the photoconductive layer receives and absorbs light, and a current flows through the pin junction in the lateral direction. It is characterized by doing.

According to a second aspect of the present invention, in the semiconductor photoelectric conversion element according to the first aspect, the pair of barrier layers, the photoconductive layer, and the contact semiconductor layer are formed by a crystal growth method. And etching between the portion on the first flat portion and the portion on the slope portion of the same layer of the contact semiconductor layer to form the contact semiconductor layer on the photoconductive layer in a plane orientation. The conductivity type of the contact semiconductor layer on the first flat portion becomes p-type,
It is characterized in that the contact semiconductor layer on the slope portion is formed so that the conductivity type is n-type.

[0007]

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

FIG. 1 is a cross-sectional view taken along the line AA ′ of FIG. 2 showing a configuration of a lateral pin junction semiconductor photoelectric conversion element according to an embodiment of the present invention. FIG. 3 is a plan view of the lateral pin junction semiconductor photoelectric conversion device of FIG. 1.

The lateral pin-junction type semiconductor photoelectric conversion device of this embodiment has a semiconductor substrate 10 having a slope 10b between a first flat portion 10a and a second flat portion 10c.
After the photoconductive layer 12 sandwiched between the pair of barrier layers 11 and 13 is formed thereon, the contact semiconductor layers 14a, 14b and 14c are formed on the photoconductive layer 12 by the first and second planes depending on the plane orientation. Contact semiconductor layer 14 on flat portion 10a
By forming the conduction type of a to be p-type and the conduction type of the contact semiconductor layer 14b on the slope portion 10b to be n-type, the lateral p-i- including the i-type photoconductive layer 12 is formed.
It is characterized by forming an n-junction, receiving and absorbing light by the photoconductive layer 12, and performing photoelectric conversion by passing a current through a lateral pin junction.

The details of the procedure for fabricating the lateral pin junction semiconductor photoelectric conversion device of the present embodiment will be described with reference to FIGS.

A plane (1,1,1) A plane (flat portion 10a in FIG. 1) which is an upper surface of a semi-insulating semiconductor substrate 10 made of GaAs doped with CrO and having a thickness of 400 μm and having a thickness of 400 μm. Slope 1 of a slope having an orientation (3,1,1) A
Steps are performed by wet etching so that 0b is formed, and thereby flat portions 10a, 10a having plane orientations (1,1,1) A on both sides of the inclined portion 10b.
c is formed. The following crystal growth was performed by molecular beam epitaxy on the semiconductor substrate 10 subjected to the step processing.

(1) 5 × 10 ¹⁶ / c of Si as an impurity
50 nm thick Al _0.3 Ga _0.7 doped with m ³
A barrier layer 11 made of As. (2) A photoconductive layer 12 serving as a light absorbing layer made of GaAs having a thickness of 1000 nm and doped with Si as an impurity by 5 × 10 ¹⁶ / cm ³ . (3) A barrier layer 13 made of Al _0.3 Ga _0.7 As and having a thickness of 50 nm and doped with Si as an impurity by 5 × 10 ¹⁶ / cm ³ . (4) 200 nm thick GaAs contact semiconductor layer 14 doped with Si as an impurity by 3 × 10 ¹⁸ / cm ³ (the contact semiconductor layer 17 before etching, which will be described later in detail, is referred to as 14). .

At this time, in the contact semiconductor layer 14a made of GaAs on the plane of the flat portion 10a having the plane direction (1,1,1) A, the conductivity type is changed to p by replacing the added silicon with As atoms. In the contact semiconductor layer 14b on the slope portion 10b having the plane orientation (3,1,1) A, the silicon replaces Ga atoms, and the conductivity type is n-type. By using the stepped substrate as described above, it becomes possible to form a p-type region and an n-type region in the same growth layer 14 due to a difference in plane orientation.

Next, an n-type electrode 16 made of AuGe / Ni / Au and having a thickness of 1000/300/1500 ° is placed on the inclined surface 10b having the plane orientation (3,1,1) A. After a p-type electrode 15 made of Zn / Au and having a thickness of 300/2000 ° is formed on the flat portion 10a having (1,1,1) A by a lift-off method, a heat treatment is performed at about 400 ° C. for 1 minute. Got an ohmic connection.
Lastly, the contact semiconductor layer 14 between the contact semiconductor layers 14a and 14b, which is the silicon-added layer of the light receiving portion.
Was removed by wet etching using an ammonia-based solution as shown in FIG. By using the ammonia-based etching solution, the barrier layer 13 made of Al _0.3 Ga _0.7 As served as an etching stopper.

A series circuit of a DC power supply 20 and a load resistor 21 is connected between the n-type electrode 16 and the p-type electrode 15, where
The positive electrode of DC power supply 20 is connected to n-electrode 16, while the negative electrode of DC power supply 20 is connected to p-type electrode 15. Thus, an electric field is applied between the n-type electrode 16 and the p-type electrode 15 in the lateral direction. In this state, when light is incident through the light receiving portion 17, photocarriers are generated in the photoconductive layer 12 made of GaAs. The optical carrier has a pair of barrier layers 1
Bands are confined in the photoconductive layer 12 sandwiched between the photoconductive layers 1 and 13 and can move at a high speed in the photoconductive layer 12 without being subjected to ion scattering in the direction of the electric field. Here, the p-type contact semiconductor layer 14a, the i-type photoconductive layer 12, and the n-type contact semiconductor layer 14c constitute a lateral pin junction type photodiode. Therefore, a current flows through the pin junction in the lateral direction due to the movement of the photocarriers in the photoconductive layer 12, whereby the load resistance 21 connected between the p-type electrode 15 and the n-type electrode 16 is changed. And the photoelectric conversion operation is performed.

Here, the photocarriers are confined within the photoconductive layer 12 in terms of band energy, and
Can move at high speed along the direction of the electric field without being subjected to ion scattering, so that high-speed operation at the time of photoelectric conversion becomes possible.

Further, since the photoelectric conversion element has a very simple structure without an insulating layer, the element can be easily reduced in size. Since the electrodes can be arranged on the same plane, they can be arranged in an array.

Further, by using the semi-insulating semiconductor substrate 10, the insulation between the respective elements is maintained, so that it is possible to easily mount other elements when installing the same. Furthermore, since a single crystal substrate is used as the semiconductor substrate 10, V-groove etching utilizing anisotropy of the crystal plane orientation is also possible. Optical connection of an optical fiber cable (not shown) with high precision and non-alignment can also be realized.

If the contact semiconductor layer 14, which is a silicon doped layer, is not removed with an ammonia-based solution,
Since the pn junction is formed on the substrate, the light emitting device is manufactured simultaneously with the light receiving device. In this case, the p-type electrode 15
When an electric field is applied between the P-type electrode 16 and the n-type electrode 16 (p-type electrode is on the positive side and n-type electrode is on the negative side), light is emitted by recombination of electrons and holes at the pn junction.

In this embodiment, the pin in the horizontal direction is
The reason for using the junction is that, in addition to the fact that the fabrication is easy, the barrier layer 13 that confine the light in the vertical direction does not easily allow a current to flow. Since current can be injected into the photoconductive layer 12 from the lateral direction, the conductivity of the barrier layer 13 can be neglected.

As described above, according to the present embodiment, the horizontal pin junction that enables high-speed photoelectric conversion is provided in the light receiving portion 17. Further, by manufacturing the semiconductor device on the semi-insulating planar semiconductor substrate 10, a portion other than the light receiving element portion can be used as a substrate for mounting other elements.

Further, in the optical / electrical fusion circuit, fine light emitting elements and light receiving elements can be provided in a state where they are positioned on the same substrate with high precision. In addition, in order to enable high-speed photoelectric conversion, a single-crystal semiconductor thin film material was used for the photoconductive layer 12 as an active part. Thereby, electrons excited by external light can move at high speed in the photoconductive layer 12 without being subjected to ion scattering, and high-speed operation can be obtained in the photoelectric conversion operation.

The photoelectric conversion element is manufactured on a semi-insulating single crystal plane semiconductor substrate 10, and any electrode can be provided on the plane. On the semiconductor substrate 10, it is electrically separated, and it becomes possible to install another element on the same substrate. In addition, since the single-crystal semiconductor substrate 10 is used as the substrate, it is easy to form a shape generally called a V-groove for connecting an optical fiber cable without alignment.

There is no extra structure such as an insulating layer in the manufacture of the photoelectric conversion element, and the element can be easily miniaturized. It is also easy to manufacture them in an array. Further, a light-emitting element can be manufactured with substantially the same structure as the light-receiving element of the present embodiment. Therefore, it is possible to simultaneously manufacture fine light emitting elements and light receiving elements positioned with high precision required for the MMIC on the same substrate.

<Modification> In the present embodiment, GaAs is used as the single crystal semiconductor substrate.
It may be composed of nP, GaN, a sapphire substrate, or the like.

In the above embodiment, the layers 11 to 14 are crystal-grown using the molecular beam epitaxy method. However, the present invention is not limited to this, and the crystal growth method such as the metal organic chemical vapor deposition method may be used. Good.

In the above embodiment, the plane orientation (1, 1,
1) The stepped semiconductor substrate 10 having a flat portion having A and a slope portion having a plane orientation of (3,1,1) A was used.
(1,0,0), (2,1,1), (4,1,1),
Other plane orientations such as (5,1,1) can be used. When other plane orientations are used, there is a relationship as shown in FIG. 3, and by setting the V / III ratio during crystal growth, the p-type and n-type semiconductor layers can be formed in the same plane as in this embodiment. Can be formed. As is clear from FIG. 3, for example,
When forming the (3,1,1) A-plane inclined portion 14b having the inclination angle θ = 29.5 °, the lateral pn junction is selected by selecting 3 to 5 as the V / III ratio. Can be formed.

[0028]

As described in detail above, the semiconductor photoelectric conversion device according to the present invention comprises a pair of barrier layers on a semiconductor substrate having a slope between a first flat portion and a second flat portion. After the formation of the photoconductive layer sandwiched between them, the contact semiconductor layer is formed on the photoconductive layer, the conductivity type of the contact semiconductor layer on the first flat portion becomes p-type due to the difference in plane orientation, and the slope portion is formed. By forming the upper contact semiconductor layer so that the conductivity type is n-type, the lateral p-type layer including the i-type photoconductive layer can be formed.
A semiconductor photoelectric conversion element having an i-n junction formed therein, wherein the photoconductive layer receives and absorbs light, and performs photoelectric conversion by passing a current through a lateral p-i-n junction.

Therefore, according to the present invention, a horizontal pin junction that enables high-speed photoelectric conversion is provided in the light receiving portion. Further, by manufacturing the semiconductor device on a semi-insulating flat semiconductor substrate, a portion other than the light receiving element portion can be used as a substrate for mounting other elements. Further, in the optical / electrical fusion circuit, fine light emitting elements and light receiving elements can be provided in a state where they are positioned on the same semiconductor substrate with high accuracy.
Further, in the photoconductive layer sandwiched between the pair of barrier layers,
Electrons excited by external light can move at high speed in the photoconductive layer without being subjected to ion scattering, and high-speed operation can be obtained in the photoelectric conversion operation.

The photoelectric conversion element is manufactured on a semiconductor substrate, and any electrode can be provided on a plane. On a semiconductor substrate, the elements are electrically separated, and another element can be provided on the same substrate. Also,
Since a semiconductor substrate is used, it is easy to form a shape generally called a V-groove for connecting an optical fiber cable without alignment.

There is no extra structure such as an insulating layer in the manufacture of the photoelectric conversion element, and the element can be easily miniaturized. It is also easy to manufacture them in an array. Further, a light-emitting element can be manufactured with substantially the same structure as the light-receiving element of the present invention. Therefore, it is possible to simultaneously manufacture fine light emitting elements and light receiving elements positioned with high precision required for the MMIC on the same substrate.

[Brief description of the drawings]

FIG. 1 is a lateral direction pi according to an embodiment of the present invention.
A of FIG. 2 showing a configuration of a -n junction type semiconductor photoelectric conversion element.
It is sectional drawing of the -A 'plane.

FIG. 2 is a plan view of the lateral pin junction semiconductor photoelectric conversion device of FIG.

FIG. 3 is a graph showing the growth condition of the conductivity type of the GaAs layer on the (111) A plane doped with Si and the dependence of the substrate on the inclination angle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Semiconductor substrate, 11 ... Barrier layer, 12 ... Photoconductive layer, 13 ... Barrier layer, 14a, 14b, 14c ... Contact layer, 15, 16 ... Electrode, 20 ... DC power supply, 21 ... Load resistance.

────────────────────────────────────────────────── ─── Continued on the front page (72) Norifumi Egami, Inventor No. 5, Sanraya, Inaya, Seika-cho, Soraku-gun, Kyoto 5 -1111539 (JP, A) JP-A-63-102282 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 31/10-31/119

Claims (2)

(57) [Claims] 1. A photoconductive layer sandwiched between a pair of barrier layers is formed on a semiconductor substrate having a slope between a first flat portion and a second flat portion. A contact semiconductor layer is formed on the layer so that the conductivity type of the contact semiconductor layer on the first flat portion becomes p-type and the conductivity type of the contact semiconductor layer on the slope portion becomes n-type due to a difference in plane orientation. By doing so, the lateral p-
A semiconductor photoelectric conversion element formed by forming an i-n junction, wherein light is received and absorbed by the photoconductive layer, and p-
A semiconductor photoelectric conversion element, wherein photoelectric conversion is performed by flowing a current through an i-n junction. 2. The semiconductor photoelectric conversion device according to claim 1, wherein the pair of barrier layers, the photoconductive layer, and the contact semiconductor layer are formed by a crystal growth method, and the same contact semiconductor layer is formed. In the layer, a portion between the portion on the first flat portion and the portion on the slope portion is etched, and the contact semiconductor layer is formed on the photoconductive layer on the first flat portion due to a difference in plane orientation. A semiconductor photoelectric conversion element formed so that the conductivity type of a contact semiconductor layer is p-type and the conductivity type of a contact semiconductor layer on an inclined surface is n-type.