US4231049A
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Heterojunction photodiode of the avalanche type
Assignee: Thales SA
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Filing: 1978-11-07
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Granted: 1980-10-28
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Expires: 1998-11-07
Abstract
Abstract A photodiode comprising a first layer of a relatively large forbidden band (e.g. 1.4 eV) in a p type of conductivity, wherein photons can be absorbed, thus creating pairs of electron-holes diffusing towards a second layer, said second layer having a forbidden band. (0.7 eV) that is approximately half of the first band. In that second layer of an n-type of conductivity each electron falls and creates by impact ionization a new pair electron-hole, thus producing an avalanche gain of 2. The phenomenon occurs theoretically with a zero bias voltage. In practice the photodiode operates with a bias voltage near zero. The two materials of the heterojunction are for instance In P (forbidden band: 1.4 eV) and Ga 0 .47 In 0 .53 As (0.7 eV) providing crystalline networks perfectly matched.
Inventors
- 👤 Thomas Pearsall
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 22:26
CPC Classifications
H; H10; H10F; H10F30/00; H10F30/20; H10F30/21; H10F30/22; H10F30/225; H10F30/2255; H10F30/222
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
178 words
An avalanche photodiode of the type provided with a semiconductor junction consisting of two different materials having opposite types of conductivity, comprising: a first semiconductor layer of an alloy having the formula In P, intended to absorb photons the energy of which is greater than or equal to E 1 , the material constituting said first layer exhibiting a forbidden band gap having a width of E 2 , expressed in energy; a second semiconductor layer adjacent to the first layer, and formed of an alloy having the formula Ga.sub.x In.sub.1-x As wherein x=0.47 within a few thousandths, said second layer exhibiting a forbidden band gap having a width of E 3 , expressed in energy; a monocrystalline substrate having the formula In P; said semiconductor junction being formed by said first layer having a first type of conductivity, which is strongly doped, and said second layer having an opposite type of conductivity, less doped than the first layer, the energies E 1 , E 2 and E 3 complying with the following double relationship: E.sub.1 >E.sub.2 ≧2E.sub.3.
Claim 2
Dependent Claim
178 words
An avalanche photodiode of the type provided with a semiconductor junction consisting of two different materials having opposite types of conductivity, comprising: a first semiconductor layer of an alloy having the formula In P, intended to absorb photons the energy of which is greater than or equal to E 1 , the material constituting said first layer exhibiting a forbidden band gap having a width of E 2 , expressed in energy; a second semiconductor layer adjacent to the first layer, and formed of an alloy having the formula Ga.sub.x In.sub.1-x As wherein x=0.47 within a few thousandths, said second layer exhibiting a forbidden band gap having a width of E 3 , expressed in energy; a monocrystalline substrate having the formula In P; said semiconductor junction being formed by said first layer having a first type of conductivity, which is strongly doped, and said second layer having an opposite type of conductivity, less doped than the first layer, the energies E 1 , E 2 and E 3 complying with the following double relationship: E.sub.1 >E.sub.2 ≧2E.sub.3.
Claim 3
Dependent Claim
178 words
An avalanche photodiode of the type provided with a semiconductor junction consisting of two different materials having opposite types of conductivity, comprising: a first semiconductor layer of an alloy having the formula Ga Sb, intended to absorb photons the energy of which is greater than or equal to E 1 , the material constituting said first layer exhibiting a forbidden band gap having a width of E 2 , expressed in energy; a second semiconductor layer adjacent to the first layer, and formed of an alloy having the formula Al.sub.y Ga.sub.1-y Sb wherein y=0.61 within a few thousandths, said second layer exhibiting a forbidden band gap having a width of E 3 , expressed in energy; a monocrystalline substrate having the formula Ga Sb; said semiconductor junction being formed by said first layer having a first type of conductivity, which is strongly doped, and said second layer having an opposite type of conductivity, less doped than the first layer, the energies E 1 , E 2 and E 3 complying with the following double relationship: E.sub.1 >E.sub.2 ≧2E.sub.3.
Claim 4
Dependent Claim
178 words
An avalanche photodiode of the type provided with a semiconductor junction consisting of two different materials having opposite types of conductivity, comprising: a first semiconductor layer of an alloy having the formula Ga Sb, intended to absorb photons the energy of which is greater than or equal to E 1 , the material constituting said first layer exhibiting a forbidden band gap having a width of E 2 , expressed in energy; a second semiconductor layer adjacent to the first layer, and formed of an alloy having the formula Al.sub.y Ga.sub.1-y Sb wherein y=0.61 within a few thousandths, said second layer exhibiting a forbidden band gap having a width of E 3 , expressed in energy; a monocrystalline substrate having the formula Ga Sb; said semiconductor junction being formed by said first layer having a first type of conductivity, which is strongly doped, and said second layer having an opposite type of conductivity, less doped than the first layer, the energies E 1 , E 2 and E 3 complying with the following double relationship: E.sub.1 >E.sub.2 ≧2E.sub.3.
Claim 5
Dependent Claim
219 words
An avalanche photodiode of the type provided with a semiconductor junction consisting of two different materials having opposite types of conductivity, comprising: a first semiconductor layer intended to absorb photons having an energy greater than or equal to E 1 , the material constituting said first layer exhibiting a forbidden band gap having a width of E 2 (expressed in energy); a second semiconductor layer adjacent to the first layer and intended to serve as an avalanche zone; said second layer exhibiting a forbidden band gap having a width of E 3 (expressed in energy) and complying with the following double relationship, E.sub.1 >E.sub.2 ≧2E.sub.3 ; said avalanche photodiode comprising a first p (or n) doped layer with a density in acceptor (or donor) atoms of 2.10 18 cm -3 , a second n (or p) doped layer with a density in donor (or acceptor) atoms of the order of 10 16 cm -3 , a third layer, serving as a buffer, of an alloy identical with that of which the substrate consists, n (or p) doped and with a density in donor (or acceptor) atoms of the order of 10 18 cm -3 , and an n (or p) doped substrate with a density in donor (or acceptor) atoms of the order of 2.10 18 cm -3 .
Claim 6
Dependent Claim
219 words
An avalanche photodiode of the type provided with a semiconductor junction consisting of two different materials having opposite types of conductivity, comprising: a first semiconductor layer intended to absorb photons having an energy greater than or equal to E 1 , the material constituting said first layer exhibiting a forbidden band gap having a width of E 2 (expressed in energy); a second semiconductor layer adjacent to the first layer and intended to serve as an avalanche zone; said second layer exhibiting a forbidden band gap having a width of E 3 (expressed in energy) and complying with the following double relationship, E.sub.1 >E.sub.2 ≧2E.sub.3 ; said avalanche photodiode comprising a first p (or n) doped layer with a density in acceptor (or donor) atoms of 2.10 18 cm -3 , a second n (or p) doped layer with a density in donor (or acceptor) atoms of the order of 10 16 cm -3 , a third layer, serving as a buffer, of an alloy identical with that of which the substrate consists, n (or p) doped and with a density in donor (or acceptor) atoms of the order of 10 18 cm -3 , and an n (or p) doped substrate with a density in donor (or acceptor) atoms of the order of 2.10 18 cm -3 .
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) | 1983-10-28 | 1984-04-28 | 1984-10-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-10-28 | 1988-04-28 | 1988-10-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-10-28 | 1992-04-28 | 1992-10-28 | $7700.00 | Window Closed / Lapsed |