High sensitivity silicon avalanche photodiode

• US 5,596,186 A
• Filed: 12/06/1994
• Issued: 01/21/1997
• Est. Priority Date: 12/08/1993
• Status: Expired due to Fees

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Kobayashi, Koji
• Primary Examiner(s): LE, QUE TAN
• Application Number:
  US08/354,731
• Time in Patent Office: 777 Days
• Field of Search: 250/214.1, 250/214 LA, 257/186, 257/438, 257/189, 257/199, 257/443
• US Class Current: 250/214.1
• CPC Class Codes: E21B 49/006 Measuring wall stresses in the borehole
• CPC Class Codes: G01B 11/16 for measuring the deformation in a solid, e.g. optical strain gauge
• CPC Class Codes: H01L 27/14643 Photodiode arrays; MOS imagers
• CPC Class Codes: H01L 31/107 the potential barrier working in avalanche mode, e.g. avalanche photodiodes

Abstract

A silicon avalanche photodiode for ultraviolet light detection having a p⁺ -layer, an n-layer, an n^- -layer and an n⁺ -silicon substrate in the order from the entrance side of the ultraviolet light, wherein the p⁺ -layer has a thickness at least equal to 0.7/α in which α is the absorption coefficient of silicon to the ultraviolet light. Also, a divided silicon avalanche photodiode provided with a photosensor array comprising plural light-receiving areas arranged in a matrix and having a guard ring only at the external periphery of the photosensor array.

Claims

1. A silicon avalanche photodiode for detecting ultraviolet light, the silicon avalanche photodiode comprising a p⁺ -layer, an n-layer, an n^- -layer and an n⁺ -silicon substrate in order from an entrance side of the ultraviolet light, wherein said p⁺ -layer has a thickness at least equal to 0.7/α

in which α

is the absorption coefficient of silicon to the ultraviolet light.

2. A silicon avalanche photodiode comprising:

a photosensor array having plural light-receiving areas arranged in a matrix; and

a guard ring formed only at the external periphery of said photosensor array and overlapping an edge of each of the plural light-receiving areas.

3. A silicon avalanche photodiode according to claim 2, wherein an area present between mutually neighboring light-receiving areas in said photosensor array is a depletion layer during the function of the silicon avalanche photodiode.

4. A silicon avalanche photodiode for detecting ultraviolet light, the silicon avalanche photodiode comprising:

a photosensor array having plural light-receiving areas arranged in a matrix, the photosensor array having a p⁺ -layer, an n-layer, an n^- -layer and an n⁺ -silicon substrate in order from an entrance side of the ultraviolet light, wherein said p⁺ -layer has a thickness at least equal to 0.7/α

in which α

is an absorption coefficient of silicon to the ultraviolet light; and

a guard ring formed only at the external periphery of said photosensor array and overlapping an edge of each of the plural light-receiving areas.

5. A silicon avalanche photodiode according to claim 4, wherein an area present between mutually neighboring light-receiving areas in said photosensor array is a depletion layer during the function of the silicon avalanche photodiode.

6. A silicon avalanche photodiode comprising:

a photosensor array having plural areas for receiving ultraviolet light, wherein said photosensor array includes

an electrode layer,

a silicon substrate layer formed on said electrode layer,

an epitaxially grown layer formed on said silicon substrate layer,

each of the plural areas formed in and at a surface of said epitaxially grown layer and spaced apart from an adjacent one of the plural areas by a depletion layer, and

a plurality of diffusion areas formed respectively underneath said plural areas and in said epitaxially grown layer; and

a guard ring formed only around a periphery of said photosensor array.

7. A silicon avalanche photodiode as claimed in claim 6, wherein:

said silicon substrate layer has an n⁺ conductivity;

said epitaxially grown layer has an n^- conductivity;

each of said plural areas has a p⁺ conductivity;

each of said plurality of diffusion areas has an n conductivity; and

each of said plural areas of p⁺ conductivity has a thickness at least equal to 0.7/α

, wherein α

is an absorption coefficient of silicon to the ultraviolet light.

8. A silicon avalanche photodiode as claimed in claim 6, wherein:

said silicon substrate layer has a p⁺ conductivity;

said epitaxially grown layer has a p^- conductivity;

each of said plural areas has an n⁺ conductivity; and

each of said plurality of diffusion areas has a p conductivity.

9. A silicon avalanche photodiode as claimed in claim 8, wherein said photosensor array further comprises channel cuts formed between adjacent ones of said plural areas.