JP-2026074560-A - Light-receiving element and method for manufacturing the same

Abstract

[Problem] To provide a photodetector capable of reducing dark current and a method for manufacturing the same. [Solution] A photodetector comprising a first semiconductor layer having a first conductivity type, a second semiconductor layer, a light-receiving layer, and a third semiconductor layer having a second conductivity type, wherein the first semiconductor layer, the second semiconductor layer, the light-receiving layer, and the third semiconductor layer are stacked in this order, the second semiconductor layer, the light-receiving layer, and the third semiconductor layer form a first mesa, and in the direction in which the light-receiving layer expands, the width of the second semiconductor layer is smaller than the width of the light-receiving layer. [Selection Diagram] Figure 2

Inventors

• 岡田 毅

Assignees

• 住友電気工業株式会社

Dates

Publication Date

20260507

Application Date

20241021

Claims (9)

1. A first semiconductor layer having a first conductivity type, The second semiconductor layer, The light-receiving layer, It comprises a third semiconductor layer having a second conductivity type, The first semiconductor layer, the second semiconductor layer, the light-receiving layer, and the third semiconductor layer are stacked in this order. The second semiconductor layer, the light-receiving layer, and the third semiconductor layer form a first mesa. A photodetector in which the width of the second semiconductor layer is smaller than the width of the light-receiving layer in the direction in which the light-receiving layer expands.
2. The aforementioned second semiconductor layer includes a multiplier layer and an electric field relaxation layer, The photodetector according to claim 1, wherein the width of the multiplier layer and the width of the field relaxation layer are smaller than the width of the photodetector layer.
3. The light-receiving layer is formed of indium gallium arsenide. The photodetector according to claim 2, wherein the multiplier layer is formed of aluminum gallium arsenide antimony.
4. The photodetector according to claim 2, wherein the doping concentration of the multiplier layer is lower than the doping concentration of the first semiconductor layer.
5. The third semiconductor layer includes a second mesa, The photodetector according to claim 1 or claim 2, wherein the width of the second mesa is smaller than the width of the second semiconductor layer.
6. The present invention comprises a fourth semiconductor layer laminated between the light-receiving layer and the third semiconductor layer, The photodetector according to claim 5, wherein the fourth semiconductor layer is included in the first mesa and the second mesa.
7. The first semiconductor layer has an n-type conductivity, The photodetector according to claim 1 or claim 2, wherein the third semiconductor layer has a p-type conductivity.
8. A process of stacking a first semiconductor layer, a second semiconductor layer, a light-receiving layer, and a third semiconductor layer in this order, The process includes a step of forming a mesa by wet etching the second semiconductor layer, the light-receiving layer, and the third semiconductor layer, The first semiconductor layer has a first conductivity type, The second semiconductor layer has a second conductivity type, A method for manufacturing a photodetector, wherein, after the wet etching, the width of the second semiconductor layer is smaller than the width of the photodetector in the direction in which the photodetector expands.
9. The aforementioned second semiconductor layer includes a multiplier layer and an electric field relaxation layer, The width of the multiplier layer and the width of the electric field relaxation layer are smaller than the width of the light receiving layer. The light-receiving layer is formed of indium gallium arsenide. The multiplier layer is formed of aluminum gallium arsenide antimony. The method for manufacturing a photodetector according to claim 8, wherein the wet etching etchant contains citric acid.

Description

This disclosure relates to a photodetector and a method for manufacturing the same. In photodetectors, mesas are formed to isolate the elements (for example, Patent Document 1). Japanese Patent Publication No. 2005-328036 Figure 1 is a plan view illustrating a light-receiving element according to an embodiment.Figure 2 is a cross-sectional view illustrating a light-receiving element.Figure 3A is a cross-sectional view illustrating a light-receiving element.Figure 3B is a cross-sectional view illustrating a light-receiving element.Figure 3C is a cross-sectional view illustrating a light-receiving element.Figure 3D is a cross-sectional view illustrating a light-receiving element.Figure 4A is a cross-sectional view illustrating a method for manufacturing a light-receiving element.Figure 4B is a cross-sectional view illustrating a method for manufacturing a light-receiving element.Figure 5 is a cross-sectional view illustrating a light-receiving element according to a comparative example. [Description of Embodiments in this Disclosure] First, the contents of the embodiments of this disclosure will be listed and explained. One embodiment of the present disclosure is a photodetector comprising (1) a first semiconductor layer having a first conductivity type, a second semiconductor layer, a light-receiving layer, and a third semiconductor layer having a second conductivity type, wherein the first semiconductor layer, the second semiconductor layer, the light-receiving layer, and the third semiconductor layer are stacked in this order, the second semiconductor layer, the light-receiving layer, and the third semiconductor layer form a first mesa, and in the direction in which the light-receiving layer expands, the width of the second semiconductor layer is smaller than the width of the light-receiving layer. The width of the depletion region is about the same as the width of the second semiconductor layer and smaller than the width of the light-receiving layer. Dark current can be reduced because an electric field is less likely to be applied to the edge of the light-receiving layer. (2) In (1) above, the second semiconductor layer includes a multiplier layer and an electric field relaxation layer, and the width of the multiplier layer and the width of the electric field relaxation layer may be smaller than the width of the light-receiving layer. The light-receiving element is an avalanche photodiode and has high sensitivity. Since an electric field is less likely to be applied to the edge of the light-receiving layer, the dark current can be reduced. (3) In (2) above, the light-receiving layer may be formed of indium gallium arsenide, and the multiplier layer may be formed of aluminum gallium arsenide antimony. The etching rate of the multiplier layer is higher than the etching rate of the light-receiving layer. The multiplier layer is etched and its width is reduced. (4) In (2) or (3) above, the doping concentration of the multiplier layer may be lower than the doping concentration of the first semiconductor layer. Depletion occurs sequentially from the multiplier layer. The width of the depletion region is about the same as the width of the multiplier layer and smaller than the width of the photodetector layer. Dark current can be reduced. (5) In any of (1) to (4) above, the third semiconductor layer includes a second mesa, and the width of the second mesa may be smaller than the width of the second semiconductor layer. The electric field is narrowed by the second mesa and applied to the layer directly below the second mesa. The electric field is applied to the portion of the light-receiving layer below the second mesa. Since the electric field is less likely to concentrate at the edges of the light-receiving layer, the dark current can be reduced. (6) In any of (1) to (5) above, a fourth semiconductor layer is laminated between the light-receiving layer and the third semiconductor layer, and the fourth semiconductor layer may be included in the first mesa and the second mesa. The capacitance of the light-receiving element decreases as the fourth semiconductor layer becomes depleted. (7) In any of (1) to (6) above, the first semiconductor layer may have an n-type conductivity and the third semiconductor layer may have a p-type conductivity. A pin junction is formed. (8) A method for manufacturing a photodetector comprising the steps of stacking a first semiconductor layer, a second semiconductor layer, a photodetector layer, and a third semiconductor layer in this order, and forming a mesa by wet etching the second semiconductor layer, the photodetector layer, and the third semiconductor layer, wherein the first semiconductor layer has a first conductivity type, the second semiconductor layer has a second conductivity type, and after the wet etching, in the direction in which the photodetector layer expands, the width of the second semiconductor layer is smaller than the width of the photodetector layer. The widt