US4316201A
Expired / Lapsed
US
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Low-barrier-height epitaxial Ge-GaAs mixer diode
Assignee: United States Department of the Navy
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Filing: 1980-05-08
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Granted: 1982-02-16
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Expires: 2000-05-08
Abstract
Abstract A high-frequency (9.3 GH z -94 GH z ) gallium arsenide (GaAs) mixeriode having a low Schottky barrier height (approximately 0.4 eV) for operating at low noise figure levels at low local oscillator power levels (0.25 mW -0.75 mW), includes a GaAs substrate, a thin (about 100 A) epitaxial layer of germanium on the substrate, the epitaxial germanium being deposited at a rate of about 6 A per minute and at a substrate temperature in the range of 325° C.-425° C., a layer of silicon dioxide (SiO 2 ), the SiO 2 being etched, and layers of platinum-titanium-molybdenum-gold on the growth of epitaxial germanium. Contact areas are then plated with a layer of gold. Ohmic contact to the GaAs substrate side includes a deposition of gold-germanium alloy. Each of the layers are individually deposited at certain temperatures and thicknesses in a vacuum.
Inventors
- 👤 Aristos Christou
- 👤 John E. Davey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 08:24
CPC Classifications
H; H10; H10D; H10D8/00; H10D8/60; H10D30/00; H10D30/60; H10D30/67; H10D30/6729; H10D30/6737; H10D30/6738; H10D30/674; H10D30/675; H10D62/00; H10D62/80; H10D62/85; H10D64/00; H10D64/01; H10D64/012; H10D64/0124; H10D64/60; H10D64/64; Y; Y10; Y10S; Y10S148/00; Y10S148/02; Y10S148/072; Y10S148/139
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
180 words
In a gallium arsenide (GaAs) mixer diode having a low Schottky-barrier height in the range of approximately 0.40 eV-0.55 eV for operating at high frequencies (X-band and above) at low local oscillator power levels (about 0.25 mW-0.75 mW), the mixer diode having a GaAs substrate, a GaAs epitaxial layer on the GaAs substrate, a refractory metal overlayer structure, a conducting layer of metal on the overlayer structure, and an ohmic contact to the GaAs substrate, the improvement comprising: a thin heterojunction epitaxial layer of germanium on the GaAs epitaxial layer, said refractory metal overlayer structure being on the epitaxial layer of germanium, the thickness of the epitaxial layer of germanium being sufficient for tunneling of electrons from the metal overlayer to the GaAs and for producing an effective lowering of the Schottky barrier height, the GaAs being maintained at a temperature, during deposition of the epitaxial germanium on the GaAs, sufficient to develop an epitaxial growth for completely covering and uniformly wetting the GaAs, and the epitaxial germanium being deposited on the GaAs at a rate sufficient for epitaxial growth.
Claim 2
Dependent Claim
180 words
In a gallium arsenide (GaAs) mixer diode having a low Schottky-barrier height in the range of approximately 0.40 eV-0.55 eV for operating at high frequencies (X-band and above) at low local oscillator power levels (about 0.25 mW-0.75 mW), the mixer diode having a GaAs substrate, a GaAs epitaxial layer on the GaAs substrate, a refractory metal overlayer structure, a conducting layer of metal on the overlayer structure, and an ohmic contact to the GaAs substrate, the improvement comprising: a thin heterojunction epitaxial layer of germanium on the GaAs epitaxial layer, said refractory metal overlayer structure being on the epitaxial layer of germanium, the thickness of the epitaxial layer of germanium being sufficient for tunneling of electrons from the metal overlayer to the GaAs and for producing an effective lowering of the Schottky barrier height, the GaAs being maintained at a temperature, during deposition of the epitaxial germanium on the GaAs, sufficient to develop an epitaxial growth for completely covering and uniformly wetting the GaAs, and the epitaxial germanium being deposited on the GaAs at a rate sufficient for epitaxial growth.
Claim 3
Dependent Claim
25 words
The improvement as recited in claim 1, wherein the thickness of said epitaxial layer of germanium is in the range of approximately 100 A-150 A.
Claim 4
Dependent Claim
31 words
The improvement as recited in claim 1, wherein the temperature at which said GaAs is maintained during deposition of the epitaxial germanium is in the range of about 325° C.-425° C.
Claim 5
Dependent Claim
26 words
The improvement as recited in claim 1, wherein the rate at which said epitaxial germanium is deposited on the GaAs is about 6 A per minute.
Claim 6
Dependent Claim
179 words
A gallium arsenide (GaAs) mixer diode having a low Schottky barrier height in the range of approximately 0.40 eV-0.55 eV for operating at high frequencies (X-band and above) at low local oscillator power levels (about 0.25 mW-0.75 mW), comprising: a GaAs substrate; a GaAs epitaxial layer on the GaAs substrate; a thin heterojunction epitaxial layer of germanium on the GaAs epitaxial layer, the GaAs being maintained at a temperature, during deposition of the epitaxial germanium on the GaAs, sufficient to develop an epitaxial growth for completely covering and uniformly wetting the GaAs, and the epitaxial germanium being deposited on the GaAs at a rate sufficient for epitaxial growth; a refractory metal overlayer structure on the epitaxial layer of germanium, said refractory structure having a high temperature handling capability, and the thickness of said epitaxial layer of germanium being sufficient for tunneling of electrons from said refractory metal overlayer to the GaAs and for producing an effective lowering of the Schottky barrier height; a conducting layer of metal on the refractory structure; and an ohmic contact to the GaAs substrate.
Claim 7
Dependent Claim
179 words
A gallium arsenide (GaAs) mixer diode having a low Schottky barrier height in the range of approximately 0.40 eV-0.55 eV for operating at high frequencies (X-band and above) at low local oscillator power levels (about 0.25 mW-0.75 mW), comprising: a GaAs substrate; a GaAs epitaxial layer on the GaAs substrate; a thin heterojunction epitaxial layer of germanium on the GaAs epitaxial layer, the GaAs being maintained at a temperature, during deposition of the epitaxial germanium on the GaAs, sufficient to develop an epitaxial growth for completely covering and uniformly wetting the GaAs, and the epitaxial germanium being deposited on the GaAs at a rate sufficient for epitaxial growth; a refractory metal overlayer structure on the epitaxial layer of germanium, said refractory structure having a high temperature handling capability, and the thickness of said epitaxial layer of germanium being sufficient for tunneling of electrons from said refractory metal overlayer to the GaAs and for producing an effective lowering of the Schottky barrier height; a conducting layer of metal on the refractory structure; and an ohmic contact to the GaAs substrate.
Claim 8
Dependent Claim
27 words
The GaAs mixer diode as recited in claim 5, wherein the thickness of said epitaxial layer of germanium is in the range of approximately 100 A-150 A.
Claim 9
Dependent Claim
33 words
The GaAs mixer diode as recited in claim 5, wherein the temperature at which said GaAs is maintained during deposition of the epitaxial germanium is in the range of about 325° C.-425° C.
Claim 10
Dependent Claim
28 words
The GaAs mixer diode as recited in claim 1, wherein the rate at which said epitaxial germanium is deposited on the GaAs is about 6 A per minute.
Claim 11
Dependent Claim
17 words
The GaAs mixer diode as recited in claim 1, wherein said refractory metal overlayer structure includes platinum-titanium-molybdenum-gold.
Claim 12
Dependent Claim
17 words
The GaAs mixer diode as recited in claim 1, wherein said conducting layer of metal is gold.
Claim 13
Dependent Claim
23 words
The GaAs mixer diode as recited in claim 1, wherein said ohmic contact is a gold-germanium alloy (approximately 88% gold - 12% germanium).
Claim 14
Dependent Claim
39 words
The GaAs mixer diode as recited in claim 9, wherein said platinum-titanium-molybdenum-gold have thicknesses of about 1500 A, 1000 A, 2000 A and 2000 A, respectively, and are deposited at a GaAs substrate temperature of approximately 100° C.-125° C.
Claim 15
Dependent Claim
32 words
The GaAs mixer diode as recited in claim 10, wherein said layer of gold is about 5000 A in thickness and is deposited at a GaAs substrate temperature of about 100° C.
Claim 16
Dependent Claim
30 words
The GaAs mixer diode as recited in claim 11, wherein said gold-germanium alloy is approximately 3000 A thick and is deposited at a GaAs substrate temperature of about 200° C.
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) | 1985-02-15 | 1985-08-17 | 1986-02-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-02-15 | 1989-08-17 | 1990-02-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-02-15 | 1993-08-17 | 1994-02-16 | $7700.00 | Window Closed / Lapsed |