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US3886579A
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Avalanche photodiode
Assignee: Hitachi Ltd
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Filing: 1973-07-24
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Granted: 1975-05-27
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Expires: 1993-07-24
Abstract
Abstract A photodiode comprises a four-layer hyperabrupt junction semiconductor having p n Nu n or n p pi p structure and a guard ring of p or n type layer, enclosing the p-n junction defined in the p n or n p region of the p n Nu n or n p pi p structure, wherein the bottom of the guard ring reaches the Nu or pi region. By the use of the hyperabrupt junction the breakdown voltage can be comparatively small without causing any degradation in the response to the incident light and moreover a stable avalanche breakdown characteristic can be obtained with the thus formed guard ring. An avalanche photodiode having excellent characteristics inclusive of high photosensitivity can be fabricated by appropriately determining the concentration of the impurity and the thickness in the respective regions, directly affecting the avalanche characteristic. According to the present invention, it is disclosed that an avalanche photodiode having excellent characteristics can be obtained by forming through epitaxial growth of the respective regions affecting the avalanche characteristics.
Inventors
- 👤 Hirobumi Ohuchi
- 👤 Tatsuya Kamei
- 👤 Kiyoshi Tsukuda
- 👤 Takuzo Ogawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 19:41
CPC Classifications
H; H10; H10F; H10F30/00; H10F30/20; H10F30/21; H10F30/22; H10F30/225; Y; Y10; Y10S; Y10S148/00; Y10S148/007; Y10S148/037; Y10S148/049; Y10S148/12
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
361 words
An avalanche photodiode comprising: a semiconductor body having first and second principal surfaces, which body comprises a first semiconductor region of a first conductivity type and a relatively high impurity concentration, one surface of which forms said first principal surface of said body; a second semiconductor region of said first conductivity type and an impurity concentration lower than that of said first semiconductor region disposed on said first semiconductor region; a third semiconductor region of said first conductivity type and having an impurity concentration lower than that of said first region and higher than that of said second region disposed on said second semiconductor region; a fourth semiconductor region of a second conductivity type, opposite said first conductivity type, and having a relatively high impurity concentration, disposed on said third semiconductor region and defining a first PN junction therewith, the surface of said fourth semiconductor region opposite the surface thereof contacting said third semiconductor region forming said second principal surface of said body; a fifth semiconductor region of said second conductivity type and having an impurity concentration lower than that of said fourth semiconductor region contacting and surrounding said third and fourth semiconductor regions and having a thickness extending from said second principal surface of said body to beyond the interface of said second and third semiconductor regions and defining a second PN junction with said second and third semiconductor regions, which second PN junction has a breakdown voltage higher than that of said first PN junction; a first electrode disposed on said first principal surface of said semiconductor body; and a second annular-shaped electrode disposed on a peripheral portion of said fourth semiconductor region above said first PN junction, at the second principal surface of said semiconductor body thereby exposing said fourth semiconductor region to light; and wherein the thickness of said second semiconductor region between said fifth and first semiconductor regions is larger than the spread of a depletion region within said second region, while the sum of the thickness of said second and third regions is such that said diode has a quantum efficiency exceeding 50 percent for the wavelength of the light which impinges on said diode.
Claim 2
Dependent Claim
361 words
An avalanche photodiode comprising: a semiconductor body having first and second principal surfaces, which body comprises a first semiconductor region of a first conductivity type and a relatively high impurity concentration, one surface of which forms said first principal surface of said body; a second semiconductor region of said first conductivity type and an impurity concentration lower than that of said first semiconductor region disposed on said first semiconductor region; a third semiconductor region of said first conductivity type and having an impurity concentration lower than that of said first region and higher than that of said second region disposed on said second semiconductor region; a fourth semiconductor region of a second conductivity type, opposite said first conductivity type, and having a relatively high impurity concentration, disposed on said third semiconductor region and defining a first PN junction therewith, the surface of said fourth semiconductor region opposite the surface thereof contacting said third semiconductor region forming said second principal surface of said body; a fifth semiconductor region of said second conductivity type and having an impurity concentration lower than that of said fourth semiconductor region contacting and surrounding said third and fourth semiconductor regions and having a thickness extending from said second principal surface of said body to beyond the interface of said second and third semiconductor regions and defining a second PN junction with said second and third semiconductor regions, which second PN junction has a breakdown voltage higher than that of said first PN junction; a first electrode disposed on said first principal surface of said semiconductor body; and a second annular-shaped electrode disposed on a peripheral portion of said fourth semiconductor region above said first PN junction, at the second principal surface of said semiconductor body thereby exposing said fourth semiconductor region to light; and wherein the thickness of said second semiconductor region between said fifth and first semiconductor regions is larger than the spread of a depletion region within said second region, while the sum of the thickness of said second and third regions is such that said diode has a quantum efficiency exceeding 50 percent for the wavelength of the light which impinges on said diode.
Claim 3
Dependent Claim
26 words
An avalanche photodiode according to claim 1, wherein the depth rj of said fifth region from said second principal surface of said body satisfies the equation
Claim 4
Dependent Claim
17 words
An avalanche photodiode according to claim 1, wherein said fourth semiconductor region is doped with gallium atoms.
Claim 5
Dependent Claim
41 words
An avalanche photodiode according to claim 1, wherein each of said semiconductor body is made of silicon and the sum of the thicknesses of said second, third and fourth regions is within the range of from 20 to 21 Mu .
Claim 6
Dependent Claim
18 words
An avalanche photodiode according to claim 1, further including an anti-reflection film coated on said fourth semiconductor region.
Claim 7
Dependent Claim
28 words
An avalanche photodiode according to claim 1, further including means, coupled to said first and second electrodes, for applying a reverse bias voltage across said first PN junction.
Claim 8
Dependent Claim
33 words
An avalanche photodiode according to claim 1, wherein the thickness of said fifth semiconductor region is from 7 to 7.5 Mu and the thickness of said fourth semiconductor region is 0.5 Mu .
Claim 9
Dependent Claim
26 words
An avalanche photodiode according to claim 7, wherein the thickness of said second semiconductor region between said fifth and first semiconductor regions is 13 Mu .
Claim 10
Dependent Claim
19 words
An avalanche photodiode according to claim 8, wherein the thickness of said second semiconductor region is 15.5 Mu .
Claim 11
Dependent Claim
29 words
An avalanche photodiode according to claim 9, wherein the impurity concentrations of said second and third semiconductor regions are 1 X 1014 atoms/cm3 and 5 X 1015 atoms/cm3, respectively.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-05-26 | 1978-11-25 | 1979-05-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-26 | 1982-11-25 | 1983-05-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-26 | 1986-11-25 | 1987-05-27 | $7700.00 | Window Closed / Lapsed |