US5380669A
Expired / Lapsed
US
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Method of fabricating a two-color detector using LPE crystal growth
Assignee: Raytheon Co
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Filing: 1993-02-08
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Granted: 1995-01-10
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Expires: 2013-02-08
Abstract
Abstract Disclosed is a method of fabricating a two-color radiation detector, and two-color photodetectors fabricated by the method. A structure is grown upon a substrate (10) to provide, in sequence, a LPE grown LWIR n-type layer (12), a MWIR p+ type common contact layer (14), and a MWIR n-type layer (16). Following growth of the MWIR n-type layer, a layer of passivation (18) is applied, and the substrate is removed to so as to enable further processing of the structure into an array (1) of two-color photodetectors. The three layer structure is bonded, prior to further processing, to a supporting substrate (22) with an adhesive bond made to the passivation layer. The supporting substrate is comprised of IR transparent material such as Group IIB-VIA semiconductor material, Group IIIA-VA semiconductor material, Group IVA semiconductor material, sapphire, and combinations thereof. The supporting substrate may be subsequently removed after hybridizing a photodetector array (2) with readout electronics to provide a thinned detector array having a reduced cool-down time.
Inventors
- 👤 Paul R. Norton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 11:21
CPC Classifications
H; H10; H10F; H10F39/00; H10F39/10; H10F39/107; H10F30/00; H10F30/20; H10F30/21; H10F30/22; H10F30/222; H10F30/288; H10F71/00; H10F71/125; H10F71/1253; H10F71/1257; H10F77/00; H10F77/10; H10F77/14; H10F77/30; H10F77/306; H10F77/331; Y; Y02; Y02E; Y02E10/00; Y02E10/50
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
188 words
A method for fabricating a radiation detector, comprising the steps of: providing a first substrate: growing on a surface of the first substrate, by a liquid phase epitaxy process, a first layer comprised of a Group IIB-VIA semiconductor material having a first electrical conductivity and a bandgap selected for absorbing infrared radiation within a first spectral band, wherein the first spectral band includes LWIR radiation or VLWIR radiation; growing on a surface of the first layer a second layer comprised of a Group IIB-VIA semiconductor material having a second electrical conductivity and a narrower bandgap than the first layer; growing, on a surface of the second layer, a third layer comprised of a Group IIB-VIA semiconductor material having the first electrical conductivity and a bandgap that is narrower than the bandgap of the first layer, the bandgap of the third layer being selected for absorbing infrared radiation within a second spectral band having a shorter wavelength than the first spectral band; forming a passivation layer upon a surface of the third layer: bonding a second substrate to a surface of the passivation layer; and removing the first substrate.
Claim 2
Independent Claim
188 words
A method for fabricating a radiation detector, comprising the steps of: providing a first substrate: growing on a surface of the first substrate, by a liquid phase epitaxy process, a first layer comprised of a Group IIB-VIA semiconductor material having a first electrical conductivity and a bandgap selected for absorbing infrared radiation within a first spectral band, wherein the first spectral band includes LWIR radiation or VLWIR radiation; growing on a surface of the first layer a second layer comprised of a Group IIB-VIA semiconductor material having a second electrical conductivity and a narrower bandgap than the first layer; growing, on a surface of the second layer, a third layer comprised of a Group IIB-VIA semiconductor material having the first electrical conductivity and a bandgap that is narrower than the bandgap of the first layer, the bandgap of the third layer being selected for absorbing infrared radiation within a second spectral band having a shorter wavelength than the first spectral band; forming a passivation layer upon a surface of the third layer: bonding a second substrate to a surface of the passivation layer; and removing the first substrate.
Claim 3
Dependent Claim
28 words
A method as set forth in claim 1 and further including a step of differentiating the first, second, and third layers into a plurality of back-to-back pn heterojunctions.
Claim 4
Dependent Claim
35 words
A method as set forth in claim 1 wherein the step of forming a passivation layer includes an initial step of forming a plurality of mesa structures by selectively removing portions of said third layer.
Claim 5
Dependent Claim
48 words
A method as set forth in claim 1 wherein the step of growing the third layer includes an initial step of applying a mask to the surface of the second layer, the mask having apertures made therein for defining regions wherein the third layer is to be grown.
Claim 6
Dependent Claim
39 words
A method as set forth in claim 1 wherein the first substrate is comprised of a material selected from the group consisting essentially of Group IIB-VIA semiconductor material, Group IIIA-VA semiconductor material, Group IVA semiconductor material, and combinations thereof.
Claim 7
Dependent Claim
27 words
A method as set forth in claim 1 wherein the first type of electrical conductivity is n-type, and wherein the second type of electrical conductivity is p-type.
Claim 8
Dependent Claim
31 words
A method as set forth in claim 1 wherein the second layer has a bandgap that is responsive to MWIR or SWIR radiation, and wherein the second spectral band is MWIR.
Claim 9
Dependent Claim
62 words
A method as set forth in claim 1 wherein the step of growing a second layer grows the second layer by a liquid phase epitaxy process, and wherein the step of growing a third layer grows the third layer by a growth process selected from the group consisting essentially of liquid phase epitaxy, molecular beam epitaxy, and metal organic chemical vapor deposition.
Claim 10
Dependent Claim
28 words
A method as set forth in claim 1 wherein the step of forming a passivation layer includes an initial step of planarizing the surface of the third layer.
Claim 11
Dependent Claim
32 words
A method as set forth in claim 1 wherein the step of forming a passivation layer includes a further step of depositing an anti-reflection coating on a surface of the passivation layer.
Claim 12
Dependent Claim
56 words
A method as set forth in claim 1 wherein the step of bonding a second substrate to a surface of the passivation layer includes a step of selecting a material for the second substrate from the group consisting essentially of Group lIB-VIA semiconductor material, Group IIIA-VA semiconductor material, Group IVA semiconductor material, sapphire, and combinations thereof.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-01-09 | 1998-07-11 | 1999-01-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-01-09 | 2002-07-11 | 2003-01-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-01-09 | 2006-07-11 | 2007-01-10 | $7700.00 | Window Closed / Lapsed |