US5780916A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Asymmetric contacted metal-semiconductor-metal photodetectors
Assignee: University of Delaware
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Filing: 1995-10-10
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Granted: 1998-07-14
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Expires: 2015-10-10
Abstract
Abstract A metal-semiconductor-metal (MSM) photodetector, specifically a new, improved low noise device is disclosed. The disclosed device is a MSM photodiode in which the cathode and anode are made of different materials with optimal Schottky barrier heights. One of these materials is chosen to provide a high ratio of Schottky barrier height to hole transport and the other to provide a high ratio of Schottky barrier height to electron transport. The disclosed MSM photodetector is designed to allow each Schottky barrier to be individually optimized to the point that a wide bandgap Schottky barrier enhancement layer and its associated heterointerface may become unnecessary. Elimination of the charge buildup at the heterointerface enhances carrier extraction resulting in photodetectors with elevated quantum efficiency and enhanced bandwidths.
Inventors
- 👤 Paul R. Berger
- 👤 Wei Gao
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 01:05
CPC Classifications
H; H10; H10F; H10F30/00; H10F30/20; H10F30/21; H10F30/22; H10F30/227; H10F30/2275
Claims Analysis
Total Claims: 36
Claim 1
Independent Claim
69 words
A photodetector comprising: a semiconductor substrate having an active region on one surface thereof, a first set of electrodes deposited on the active region of the substrate made from a first material, a second set of electrodes deposited on the active region of the substrate made of a second material, wherein the first set and second set of electrodes are made of different metals having different Schottky barrier heights.
Claim 2
Dependent Claim
69 words
A photodetector comprising: a semiconductor substrate having an active region on one surface thereof, a first set of electrodes deposited on the active region of the substrate made from a first material, a second set of electrodes deposited on the active region of the substrate made of a second material, wherein the first set and second set of electrodes are made of different metals having different Schottky barrier heights.
Claim 3
Dependent Claim
19 words
A photodectector as claimed in claim 1, wherein the active region of the substrate is InGaAs, InGaAsP, or GaAs.
Claim 4
Dependent Claim
15 words
A photodetector as claimed in claim 1, wherein the photodetector includes a barrier enhancement layer.
Claim 5
Dependent Claim
16 words
A photodetector as claimed in claim 3, wherein the barrier enhancement layer comprises lattice matched InP.
Claim 6
Dependent Claim
20 words
A photodetector as claimed in claim 3, wherein the transition from the substrate to the barrier enhancement layer is graded.
Claim 7
Dependent Claim
20 words
A photodetector as claimed in claim 3, wherein an undoped buffer layer is interposed between the substrate and active region.
Claim 8
Dependent Claim
14 words
A photodetector as claimed in claim 3, wherein the substrate is an Fe-doped InP.
Claim 9
Dependent Claim
14 words
A photodetector as claimed in claim 3, wherein the substrate is an undoped InP.
Claim 10
Dependent Claim
16 words
A photodetector as claimed in claim 1, wherein the photodetector is electrically isolated from surrounding structures.
Claim 11
Dependent Claim
25 words
A photodetector as claimed in claim 9, wherein the electrical isolation is accomplished by etching the photodiode down to the substrate to form a mesa.
Claim 12
Dependent Claim
19 words
A photodetector as claimed in claim 10, wherein the mesa has sidewalls which are passivated with a dielectric material.
Claim 13
Dependent Claim
17 words
A photodetector as claimed in claim 11, wherein the dielectric material is silicon dioxide or silicon nitride.
Claim 14
Dependent Claim
20 words
A photodetector as claimed in claim 1, wherein the photodiode has an active region from 0.5 to 1.00 micrometers thick.
Claim 15
Dependent Claim
18 words
A photodetector as claimed in claim 1, wherein the electrodes are spaced apart by less than 1 micron.
Claim 16
Dependent Claim
17 words
A photodetector as claimed in claim 1, wherein the electrodes are spaced apart by about 300 nm.
Claim 17
Dependent Claim
18 words
A photodetector as claimed in claim 1, wherein a portion of the electrodes are about 1 micron wide.
Claim 18
Dependent Claim
19 words
A photodetector as claimed in claim 1, wherein a portion of the electrodes are less than 1 micron wide.
Claim 19
Dependent Claim
17 words
A photodetector as claimed in claim 1, wherein a portion of the electrodes are 300 micrometers wide.
Claim 20
Dependent Claim
14 words
A photodetector as claimed in claim 1, wherein at least one metal is opaque.
Claim 21
Dependent Claim
18 words
A photodetector as claimed in claim 1, wherein the photodetector is at least 100 square micrometers in area.
Claim 22
Dependent Claim
21 words
A photodetector as claimed in claim 1, wherein the photodetector is from about 100 to about 10,000 square micrometers in area.
Claim 23
Dependent Claim
21 words
A photodetector as claimed in claim 1, wherein the photodetector is from about 2,500 to about 10,000 square micrometers in area.
Claim 24
Dependent Claim
16 words
A photodetector as claimed in claim 1, wherein at least one electrode is 50-100 angstroms thick.
Claim 25
Dependent Claim
19 words
A photodetector as claimed in claim 1, wherein at least one electrode is overlaid with a low resistance metal.
Claim 26
Dependent Claim
19 words
A photodetector as claimed in claim 1, wherein at least one electrode has a total thickness of 1000-5000 angstroms.
Claim 27
Dependent Claim
12 words
A photodetector as claimed in claim 24, wherein the metal is gold.
Claim 28
Dependent Claim
20 words
A photodetector as claimed in claim 1, further comprising an anti-reflective coating on the active region of the substrate surface.
Claim 29
Dependent Claim
25 words
A photodetector as claimed in claim 1, further comprising a reflective coating on at least one surface of the substrate other than the active region.
Claim 30
Dependent Claim
20 words
A photodetector as claimed in claim 1, wherein one electrode material is Ti, Ag, Pt, Ni, Cr, Al, or Ag.
Claim 31
Dependent Claim
15 words
A photodetector as claimed in claim 1, wherein one electrode material is a refractory metal.
Claim 32
Dependent Claim
16 words
A photodetector as claimed in claim 1, wherein one electrode material is Mo, Ta, or W.
Claim 33
Dependent Claim
14 words
A photodetector as claimed in claim 1, wherein one electrode material is a silicide.
Claim 34
Dependent Claim
15 words
A photodetector as claimed in claim 1, wherein one electrode material is a transparent conductor.
Claim 35
Dependent Claim
20 words
A photodetector as claimed in claim 1, wherein one electrode material is indium oxide, cadmium oxide, or indium tin oxide.
Claim 36
Dependent Claim
10 words
The photodetector of claim 1 which is a metal-semiconductor-metal photodetector.
References Cited (Backward Citations)
US5461246A
Cited
US5568499A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-07-13 | 2002-01-12 | 2002-07-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-07-13 | 2006-01-12 | 2006-07-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-07-13 | 2010-01-12 | 2010-07-14 | $7700.00 | Window Closed / Lapsed |