JPH11186587A - Photodetecting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photodetecting element capable of detection with good sensitivity. SOLUTION: A photodetecting element is provided with a first semiconductor part 3 of a first conductivity type, and a second semiconductor part 4 of a second conductivity type, which is formed on the first semiconductor part 3 and has a conductivity type opposite to the first conductivity type, and detects a light to be detected. Semiconductor material of the second semiconductor part 4 has an absorption coefficient to the light to be detected, which is small as compared with semiconductor material of the first semiconductor part 3, and the light to be detected is introduced from the second semiconductor part 4 to the first semiconductor part 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a photodetector.

[0002]

2. Description of the Related Art Conventionally, as a photodetecting element, a photodetecting element using a pn homojunction of n-type Si (silicon) and p-type Si, or a p-type photodetector using n-type SiC (silicon carbide) and p-type SiC.
A photodetector using an n-homo junction is known.

On the other hand, in order to realize high-density recording on an optical recording medium, a semiconductor laser device having a short wavelength from near-ultraviolet light (for example, 400 nm) to visible light in the vicinity thereof has been actively researched and developed.

[0004]

However, the above S
In the photodetector made of i, there is a problem that Si absorbs a large amount of ultraviolet light from visible light in the vicinity of the ultraviolet light, and the light does not sufficiently reach the light detection region. In order to solve this problem, the thickness of the Si layer on the light introduction side may be reduced, but in this case, it may be difficult to manufacture an ohmic electrode or to perform element processing as a pre-treatment.

In the above-described photodetector made of SiC, the SiC absorbs only a small amount of ultraviolet light from visible light in the vicinity of the ultraviolet light, and the light is not sufficiently absorbed in the photodetection region. There is a problem of passing through.

Therefore, the above-described photodetector has a problem that it is not possible to detect ultraviolet light with high sensitivity to visible light near the ultraviolet light.

The present invention has been made in view of the above problems, and has as its object to provide a photodetector capable of detecting with high sensitivity.

[0008]

Means for Solving the Problems The photodetector of the present invention comprises:
A first semiconductor portion having a first conductivity type; and a second semiconductor portion having a second conductivity type formed on the first semiconductor portion and having a conductivity type opposite to the first conductivity type. A light detecting element for detecting, wherein a semiconductor material of the second semiconductor portion is the first material;
A light absorption coefficient of the detected light with respect to the semiconductor material of the semiconductor portion is smaller than that of the semiconductor material, and the detected light is introduced from the second semiconductor portion side to the first semiconductor portion.

According to the present invention, pn with the first and second semiconductor portions is provided.
A region including the junction or the opposing portion becomes a light detection region, and light is introduced from the second semiconductor portion side made of a semiconductor material having a smaller light absorption coefficient for light to be detected than the first semiconductor portion.

Therefore, it is possible to suppress the light absorption until reaching the light detection area, and to sufficiently absorb the light by the first semiconductor portion constituting the light detection area. As a result, the detected light can be detected with high sensitivity.

The photodetector does not need to have a double hetero structure in which a semiconductor portion having a small band gap is sandwiched between semiconductor portions having a larger band gap.

In particular, the second semiconductor portion substantially transmits the light to be detected, and the transmitted light to be detected is light-absorbed in a light detection region of the first semiconductor portion.

In this case, the light is hardly absorbed until the light reaches the light detection area, and the light is sufficiently absorbed by the first semiconductor portion constituting the light detection area. As a result, the detected light can be detected with high sensitivity.

Further, the second semiconductor portion has a larger band gap than the first semiconductor portion.

In this case, the semiconductor material of the second semiconductor portion can have a smaller light absorption coefficient for the detected light than the semiconductor material of the first semiconductor portion.

Further, a third semiconductor portion is formed between the second semiconductor portion and the first semiconductor portion and on the first semiconductor portion to prevent impurity diffusion.

In this case, diffusion of desired impurities between the second semiconductor portion and the first semiconductor portion can be prevented.
The light detection area is improved, and the light to be detected can be detected with higher sensitivity.

The third semiconductor portion is preferably non-doped.

The third semiconductor portion preferably has the same or wider band gap as the second semiconductor portion.

Further, the third semiconductor portion is made of the same material as the second semiconductor portion.

Further, the second semiconductor portion is made of SiC, and the first semiconductor portion is made of Si.

In this case, visible light in the vicinity of the ultraviolet light can be detected with high sensitivity.

Further, the second semiconductor portion is made of 3C-Si
C, 4H-SiC, or 6H-SiC. Here, from a manufacturing point of view, 3C
-SiC, 6H-SiC, and 4H-SiC are preferred in this order, and the reverse is preferred from the viewpoint of characteristics.

Further, a third semiconductor portion for preventing impurity diffusion is formed between the second semiconductor portion and the first semiconductor portion and on the first semiconductor portion, wherein the third semiconductor portion is formed by the third semiconductor portion. It is characterized by being made of SiC lightly doped or undoped than the second semiconductor part.

Particularly, the second semiconductor portion is made of 4H-SiC, and the first semiconductor portion is made of 3C-SiC.

A third semiconductor part is formed between the second semiconductor part and the first semiconductor part and on the first semiconductor part for preventing impurity diffusion, and the third semiconductor part is formed of 4H. −
It is characterized by being made of SiC.

This third semiconductor portion is preferably non-doped.

In particular, the detected light comprises ultraviolet light and visible light in the vicinity of the ultraviolet light. Further, the detected light is composed of near-ultraviolet light to visible light in the vicinity thereof.

The first to third semiconductor portions may be layers, and the first semiconductor portion may be used as a substrate and the second to third semiconductor portions may be used as a substrate.
A configuration in which the third semiconductor portion is a layer may be employed.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A photodetector according to a first embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of the photodetector of the present embodiment.

In FIG. 1, 1 is an n-type Si substrate, and 2 is an n-type Si substrate.
5000 mm formed by an evaporation method at an end on the substrate 1
An n-type electrode 3 made of a thick Au-Ge alloy (gold-germanium alloy) is formed on a n-type Si substrate 1 by a CVD method (chemical deposition method).
0 μm thick n-type Si layer (band gap E _Si ), 4 is n
0.1 to 2 formed by CVD on the Si layer 3
μm-thick p-type SiC layer (band gap E _SiC : E _SiC >
E _Si ), 5 is a p-type SiC layer having a thickness of 1 to 10 μm formed on a part of the p-type SiC layer 4 by a CVD method, and 6 is a 5000 ° thick layer formed on the p-type SiC layer 5 by a vapor deposition method. This is a p-type side electrode made of Al.

In the photodetector, the n-type Si layer 3 and the p-type SiC layer 4 are hetero-junction, and the region 10 including this junction is formed.
Is a light detection area, and in this area 10, visible light in the vicinity can be detected from ultraviolet light.

In such a photodetector, light is introduced from the side of the p-type SiC layer 4 made of SiC having a small light absorption coefficient from ultraviolet light to visible light in the vicinity of the ultraviolet light, and n-type S
Si constituting the i-layer 3 has a large light absorption coefficient from ultraviolet light to visible light in the vicinity thereof.

Therefore, the light is hardly absorbed until the light reaches the light detection region 10, and the light is sufficiently absorbed by the n-type Si layer 3 constituting the light detection region 10. As a result, visible light in the vicinity can be detected with high sensitivity from ultraviolet light.

Next, a photodetector according to a second embodiment of the present invention will be described in detail with reference to the drawings. FIG. 2 is a schematic configuration diagram of the photodetector of the present embodiment.

In FIG. 2, reference numeral 11 denotes an n-type Si substrate, 12 denotes an n-type Si layer having a thickness of 1 to 10 μm formed on the upper surface of the n-type Si substrate 11 by a CVD method (chemical deposition method), and 13 denotes an n-type Si layer. 0.1 to 2 formed on the Si layer 12 by the CVD method
A p-type SiC layer having a thickness of μm, 14 is a p-type SiC layer having a thickness of 1 to 10 μm formed on a part of the p-type SiC layer 13 by a CVD method, and 15 is formed on a p-type SiC layer 5 by a vapor deposition method. P-type side electrode made of 5000 mm thick Al, 16
Is an n-type side electrode made of a 5000 mm thick Au-Ge alloy (gold-germanium alloy) formed on the entire other surface of the n-type Si substrate 11 by vapor deposition.

In this photodetector, the n-type Si layer 12 and the p-type SiC layer 13 are hetero-junction, and the region 2 including this junction is formed.
0 is a light detection area, and in this area 20, visible light in the vicinity can be detected from ultraviolet light.

In this photodetector, light is introduced from the p-type SiC layer 13 made of SiC having a small light absorption coefficient from ultraviolet light to visible light in the vicinity of the ultraviolet light, and the n-type Si layer 12 is The constituent Si has a large light absorption coefficient from ultraviolet light to visible light in the vicinity thereof.

Therefore, the light is hardly absorbed until the light reaches the light detection region 20, and the light is sufficiently absorbed by the n-type Si layer 12 constituting the light detection region 10. As a result, visible light in the vicinity can be detected with high sensitivity from ultraviolet light.

In the above description, the n-type Si layer and the p-type SiC layer
Direct bonding, but prevents unwanted dopant diffusion, for example
In order to stop the doping, the doping (p
^-Type, n ^-Type or undoped SiC layer
May be formed.

In the above, 3C-S is used as the SiC layer.
iC was used, but instead of 4H-SiC or 6H-S
iC may be used.

The photodetector made of 3C-SiC / Si and the photodetector made of 6H-SiC / Si are 2
00 nm to 1 μm, more preferably 350 nm to 1 μm
Light can be detected with high sensitivity.

The 4H-SiC / Si photodetector is preferably 200 nm to 1 μm, more preferably 30 nm to 1 μm.
Light of 0 nm to 1 μm can be detected with high sensitivity.

In the above description, the n-type S
An i-layer was formed, but an n-type Si layer was formed without forming an n-type Si layer.
A configuration in which a p-type SiC layer is formed on a substrate may be employed.

Further, n-type 4H-S is formed on p-type 3C-SiC.
Even with the photodetector formed with iC, by using the n-type 4H-SiC side as the light introduction side, visible light in the vicinity of ultraviolet light can be detected with high sensitivity. This 4H-SiC / 3C-S
The photodetector made of iC is 200 nm to 500 nm,
More preferably, light of 300 nm to 500 nm can be detected with high sensitivity.

Further, the configuration may be such that the conductivity type in each of the above-described examples is the opposite conductivity type.

[0047]

According to the present invention, it is possible to provide a photodetector capable of detecting with high sensitivity.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a photodetector according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating the configuration of a photodetector according to a second embodiment of the present invention.

[Explanation of symbols]

 3 n-type Si layer 4 p-type SiC layer 12 n-type Si layer 13 p-type SiC layer

Claims (11)

[Claims] 1. A semiconductor device comprising: a first semiconductor portion of a first conductivity type; and a second semiconductor portion of a second conductivity type formed on the first semiconductor portion and having a conductivity type opposite to the first conductivity type. A light detection element for detecting light to be detected, wherein the semiconductor material of the second semiconductor portion has a smaller light absorption coefficient for the light to be detected than the semiconductor material of the first semiconductor portion, and Light is introduced into the first semiconductor unit from the second semiconductor unit side. 2. The semiconductor device according to claim 1, wherein the second semiconductor portion substantially transmits the light to be detected, and the transmitted light to be detected is light-absorbed in a light detection region of the first semiconductor portion.
The photodetector according to any one of the preceding claims. 3. The photodetector according to claim 1, wherein the second semiconductor section has a larger band gap than the first semiconductor section. 4. The semiconductor device according to claim 1, further comprising a third semiconductor portion between said second semiconductor portion and said first semiconductor portion, said third semiconductor portion being formed on said first semiconductor portion to prevent impurity diffusion. ~
4. The photodetector according to at least one of 3. 5. The photodetector according to claim 4, wherein the third semiconductor portion is made of the same material as the second semiconductor portion. 6. The photodetector according to claim 1, wherein the second semiconductor portion is made of SiC, and the first semiconductor portion is made of Si. 7. A third semiconductor portion between the second semiconductor portion and the first semiconductor portion for preventing impurity diffusion is formed on the first semiconductor portion, wherein the third semiconductor portion is formed by the third semiconductor portion. 7. The photodetector according to claim 6, wherein the photodetector is made of SiC lightly doped or undoped than the second semiconductor part. 8. The semiconductor device according to claim 8, wherein the second semiconductor portion is 3C-SiC,
The photodetector according to any one of claims 6 to 7, wherein the photodetector is made of one of H-SiC and 6H-SiC. 9. The photodetector according to claim 1, wherein the second semiconductor section is made of 4H—SiC, and the first semiconductor section is made of 3C—SiC. . 10. A third semiconductor portion between the second semiconductor portion and the first semiconductor portion for preventing impurity diffusion is formed on the first semiconductor portion, wherein the third semiconductor portion is 4H -S
10. The photodetector according to claim 9, comprising iC. 11. The apparatus according to claim 1, wherein the light to be detected comprises ultraviolet light to visible light near the ultraviolet light.
The photodetector according to at least one of the above.