US4297176A
Expired / Lapsed
US
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Surface passivation of compound semiconductors
Assignee: National Research Development Corp UK
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Filing: 1980-02-27
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Granted: 1981-10-27
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Expires: 2000-02-27
Abstract
Abstract A compound semiconductor whose elements are differently volatile (e.g. GaAs, where As is more volatile than Ga) can be surface-passivated (a Ga layer overlying GaAs) by the steps of (a) anodizing a compound semiconductor to produce a layer thereon of native semiconductor oxide, (b) reducing the layer of oxide at elevated temperature and allowing the more volatile element of the reduced oxide to evaporate away, to leave predominantly the less volatile element overlying the compound semiconductor, (c) depositing an anodizable metal on the surface of the less volatile element, (d) re-anodizing the resulting structure until oxidation has proceeded to beyond the layer containing predominantly the less volatile element and from 10 A to 50 A into the compound semiconductor, and optionally at any suitable stage (e) applying an ohmic contact to the back surface of the compound semiconductor or selectively to the top surface as required.
Inventors
- 👤 Stephen J. Hannah
- 👤 Bryan Livingstone
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 04:11
CPC Classifications
H; H10; H10P; H10P14/00; H10P14/60; H10P14/66; H10P14/662; H10P14/63; H10P14/6302; H10P14/6304; H10P14/6306; H10P14/6314; H10P14/65; H10P14/6516; H10P14/6529; H10P14/6312; H10P14/6324; H10P14/69; H10P14/692; H10P14/6938; H10P14/6939; H10P14/69391
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
135 words
A method of surface-passivating a compound semiconductor whose elements are differently volatile, comprising the steps of (a) anodising a compound semiconductor to produce a layer thereon of native semiconductor oxide, (b) reducing all of the layer of oxide at elevated temperature and allowing the more volatile element of the reduced oxide to evaporate away, to leave predominantly the less volatile element overlying the compound semiconductor, (c) depositing an anodisable metal on the surface of the less volatile element, (d) re-anodising the resulting structure until oxidation has proceeded to beyond the layer containing predominantly the less volatile element and from 10 A to 50 A into the compound semiconductor, and optionally at any suitable stage (e) applying an ohmic contact to the back surface of the compound semiconductor or selectively to the top surface as required.
Claim 2
Independent Claim
135 words
A method of surface-passivating a compound semiconductor whose elements are differently volatile, comprising the steps of (a) anodising a compound semiconductor to produce a layer thereon of native semiconductor oxide, (b) reducing all of the layer of oxide at elevated temperature and allowing the more volatile element of the reduced oxide to evaporate away, to leave predominantly the less volatile element overlying the compound semiconductor, (c) depositing an anodisable metal on the surface of the less volatile element, (d) re-anodising the resulting structure until oxidation has proceeded to beyond the layer containing predominantly the less volatile element and from 10 A to 50 A into the compound semiconductor, and optionally at any suitable stage (e) applying an ohmic contact to the back surface of the compound semiconductor or selectively to the top surface as required.
Claim 3
Dependent Claim
13 words
The method of claim 1, wherein the compound semiconductor is a III/V semiconductor.
Claim 4
Dependent Claim
11 words
The method of claim 2, wherein the semiconductor is gallium arsenide.
Claim 5
Dependent Claim
15 words
The method of claim 3, wherein the structure is annealed at 320 to 380 C.
Claim 6
Dependent Claim
18 words
The method of claim 3, wherein in step (b) the reduction is at 400 C. to 700 C.
Claim 7
Dependent Claim
11 words
The method of claim 2, wherein the semiconductor is indium phosphide.
Claim 8
Dependent Claim
15 words
The method of claim 6, wherein the structure is annealed at 280 to 350 C.
Claim 9
Dependent Claim
18 words
The method of claim 6, wherein in step (b) the reduction is at 300 C. to 500 C.
Claim 10
Dependent Claim
10 words
The method of claim 1, wherein the structure is annealed.
Claim 11
Dependent Claim
12 words
The method of claim 9, wherein the annealing is performed in nitrogen.
Claim 12
Dependent Claim
14 words
The method of claim 9, wherein the annealing is for 10 to 30 minutes.
Claim 13
Dependent Claim
20 words
The method of claim 1, wherein in step (a) the native oxide produced is 30 A to 400 A thick.
Claim 14
Dependent Claim
17 words
The method of claim 12, wherein the native oxide produced is 50 A to 150 A thick.
Claim 15
Dependent Claim
15 words
The method of claim 1, wherein in step (b) the reduction is performed in hydrogen.
Claim 16
Dependent Claim
24 words
The method of claim 1, wherein in step (c) the anodisable metal is any one of zinc, nickel, tantalum, hafnium, zirconium, titanium and aluminium.
Claim 17
Independent Claim
131 words
A method of surface-passivating a compound semiconductor whose elements are differently volatile, comprising the steps of (a) anodising a compound semiconductor to produce a layer thereon of native semiconductor oxide, (b) reducing all of the layer of oxide at elevated temperature and allowing the more volatile element of the reduced oxide to evaporate away, to leave predominantly the less volatile element overlying the compound semiconductor, (c') oxidising the less volatile element until oxidation has proceeded to beyond the layer containing predominantly the less volatile element and from 10 A to 50 A into the compound semiconductor, (d') depositing a dielectric on the oxidised surface, and optionally at any suitable stage (e) applying an ohmic contact to the back surface of the compound semiconductor or selectively to the top surface as required.
Claim 18
Independent Claim
131 words
A method of surface-passivating a compound semiconductor whose elements are differently volatile, comprising the steps of (a) anodising a compound semiconductor to produce a layer thereon of native semiconductor oxide, (b) reducing all of the layer of oxide at elevated temperature and allowing the more volatile element of the reduced oxide to evaporate away, to leave predominantly the less volatile element overlying the compound semiconductor, (c') oxidising the less volatile element until oxidation has proceeded to beyond the layer containing predominantly the less volatile element and from 10 A to 50 A into the compound semiconductor, (d') depositing a dielectric on the oxidised surface, and optionally at any suitable stage (e) applying an ohmic contact to the back surface of the compound semiconductor or selectively to the top surface as required.
Claim 19
Dependent Claim
16 words
The method of claim 16, wherein the oxidising (c') is by one of anodisation and plasma.
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) | 1984-10-26 | 1985-04-27 | 1985-10-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-10-26 | 1989-04-27 | 1989-10-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-10-26 | 1993-04-27 | 1993-10-27 | $7700.00 | Window Closed / Lapsed |