US4568792A
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Photovoltaic cell including doped cadmium telluride, a dislocation preventing agent and improved ohmic contacts
Assignee: SRI International Inc
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Filing: 1984-02-02
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Granted: 1986-02-04
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Expires: 2004-02-02
Abstract
Abstract A photovoltaic cell includes doped cadmium telluride formed of tetrahedral crystalline host semiconductor material including cadmium and telluride atoms bonded by ionic, covalent, and metallic forces. The host material is alloyed with Group II or VI atoms that replace either some of the host material cadmium or telluride atoms so that the alloyed and host atoms are bonded by at least covalent and metallic forces. The alloyed atoms have bond lengths with the nearest neighboring host atoms that are less than the host bond lengths. The number of bonded alloyed atoms is such that they do not substantially affect electronic conduction properties of the host material and result in a semiconductor region having no more than a few dislocations. A semiconductor of opposite conductivity to the conductivity type of the semiconductor region forms a junction with the region. At least one metal electrode makes ohmic contact with the first region. If the cadmium telluride is p type, the alloyed atoms are selected from the group consisting essentially of zinc, sulphur, and selenum, in which case the n type semiconductor can be cadmium sulphide. The n and p type semiconductors can be of the same compound to form a homojunction.
Inventors
- 👤 John B. Mooney
- 👤 Arden Sher
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 07:25
CPC Classifications
H; H10; H10F; H10F10/00; H10F10/10; H10F10/16; H10F10/162; H10F10/14; H10F77/00; H10F77/10; H10F77/12; H10F77/123; Y; Y02; Y02E; Y02E10/00; Y02E10/50; Y02E10/543; Y02E10/547
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
202 words
A photovoltaic cell comprising a p type CdTe semiconductor formed of tetrahedral structural crystalline host semiconductor material including Cd and Te atoms bonded by ionic, covalent and metallic forces, the nearest Cd and Te atoms of the host material having a known bond length, the CdTe host material being alloyed with a single type of atoms that replace about 0.1 of either some of the Cd or some of the Te atoms of the host material so that the alloyed and host atoms are bonded by at least covalent and metallic forces, the alloyed atoms having a bond length with the nearest neighboring host atoms that is less than the known host bond length, the number of bonded alloyed atoms being small compared to the number of bonded host atoms so as not to substantially affect electron conduction and optical properties of the host material, whereby a p type semiconductor region having low dislocation density relative to the dislocation density of the CdTe is formed, an n type semiconductor forming a junction with the p type region, and separate first and second metal electrode means respectively making ohmic contacts with the low dislocation density p type region and the n type region.
Claim 2
Dependent Claim
202 words
A photovoltaic cell comprising a p type CdTe semiconductor formed of tetrahedral structural crystalline host semiconductor material including Cd and Te atoms bonded by ionic, covalent and metallic forces, the nearest Cd and Te atoms of the host material having a known bond length, the CdTe host material being alloyed with a single type of atoms that replace about 0.1 of either some of the Cd or some of the Te atoms of the host material so that the alloyed and host atoms are bonded by at least covalent and metallic forces, the alloyed atoms having a bond length with the nearest neighboring host atoms that is less than the known host bond length, the number of bonded alloyed atoms being small compared to the number of bonded host atoms so as not to substantially affect electron conduction and optical properties of the host material, whereby a p type semiconductor region having low dislocation density relative to the dislocation density of the CdTe is formed, an n type semiconductor forming a junction with the p type region, and separate first and second metal electrode means respectively making ohmic contacts with the low dislocation density p type region and the n type region.
Claim 3
Dependent Claim
49 words
The photovoltaic cell of claim 1 wherein the single type of atoms is selected from the group consisting essentially of Zn, S, and Se, whereby the p type semiconductor is respectively Cd.sub.1-x Zn.sub.x Te, CdTe.sub.1-y S.sub.y, and CdTe.sub.1-y Se.sub.y, where x is about 0.1 and y is about 0.1.
Claim 4
Dependent Claim
32 words
The photovoltaic cell of claim 2 wherein the n type semiconductor is a compound different from the p type semiconductor, whereby a heterojunction is formed by the p and n type semiconductors.
Claim 5
Dependent Claim
70 words
The photovoltaic cell of claim 3 wherein the n type region has a band gap greater than the band gap of the p type region, the n type region being substantially transparent to a first band of optical energy that includes a second band of optical energy to which the p type region is responsive, the p type region being adapted to be positioned to be responsive to optical energy.
Claim 6
Dependent Claim
13 words
The photovoltaic cell of claim 4 wherein the n type semiconductor is CdS.
Claim 7
Dependent Claim
24 words
The photovoltaic cell of claim 4 wherein the n type semiconductor is a thin film of CdS epitaxially deposited on the p type material.
Claim 8
Dependent Claim
66 words
The photovoltaic cell of claim 2 wherein the p and n type semiconductors are compounds having the same formula, whereby the p and n type semiconductors both have low dislocation density relative to the dislocation density of the CdTe, and the second electrode means makes contact with the low dislocation density n type semiconductor, and a homojunction is formed by the p and n type semiconductors.
Claim 9
Dependent Claim
15 words
The photovoltaic cell of claim 1 whereby the p type region is a bulk material.
Claim 10
Dependent Claim
25 words
The photovoltaic cell of claim 1 further including a ceramic substrate and wherein the p type region is a thin film on the ceramic substrate.
Claim 11
Dependent Claim
206 words
A photovoltaic cell comprising a p type CdTe semiconductor formed of tetrahedral structural crystalline host semiconductor material including Cd and Te atoms bonded by ionic, covalent and metallic forces, the nearest Cd and Te atoms of the host material having a known bond length, the CdTe host material being alloyed with atoms selected from the group consisting essentially of Se and S that replace about 0.1 of the Te atoms of the host material so that the alloyed and host atoms are bonded by at least covalent and metallic forces, the alloyed atoms having a bond length with the nearest neighboring host atoms that is less than the known host bond length, the number of bonded alloyed atoms being small compared to the number of bonded host atoms so as not to substantially affect electron conduction and optical properties of the host material, whereby a p type semiconductor volume having low dislocation density relative to the dislocation density of CdTe is formed, an n type semiconductor region forming a junction with the volume of the p type semiconductor, and first and second metal electrode means respectively making separate ohmic contacts with the volumes of the low dislocation density p type semiconductor and the n type semiconductor.
Claim 12
Dependent Claim
206 words
A photovoltaic cell comprising a p type CdTe semiconductor formed of tetrahedral structural crystalline host semiconductor material including Cd and Te atoms bonded by ionic, covalent and metallic forces, the nearest Cd and Te atoms of the host material having a known bond length, the CdTe host material being alloyed with atoms selected from the group consisting essentially of Se and S that replace about 0.1 of the Te atoms of the host material so that the alloyed and host atoms are bonded by at least covalent and metallic forces, the alloyed atoms having a bond length with the nearest neighboring host atoms that is less than the known host bond length, the number of bonded alloyed atoms being small compared to the number of bonded host atoms so as not to substantially affect electron conduction and optical properties of the host material, whereby a p type semiconductor volume having low dislocation density relative to the dislocation density of CdTe is formed, an n type semiconductor region forming a junction with the volume of the p type semiconductor, and first and second metal electrode means respectively making separate ohmic contacts with the volumes of the low dislocation density p type semiconductor and the n type semiconductor.
Claim 13
Dependent Claim
29 words
The photovoltaic cell of claim 10 wherein the p type semiconductor is selected from the group consisting essentially of CdTe.sub.1-y S.sub.y and CdTe.sub.1-y Se.sub.y, where y is about 0.1.
Claim 14
Dependent Claim
16 words
The photovoltaic cell of claim 11 wherein the p and n type semiconductors are different compounds.
Claim 15
Dependent Claim
60 words
The photovoltaic cell of claim 11 wherein the p and n type semiconductors are the same compounds, whereby both semiconductors have low dislocation density relative to the dislocation density of the CdTe, and the second electrode means makes ohmic contact with the low dislocation density n type semiconductor, and a homojunction is formed by the p and n type semiconductors.
Claim 16
Dependent Claim
208 words
A photovoltaic cell comprising a p type CdTe semiconductor formed of tetrahedral structural crystalline host semiconductor material including Cd and Te atoms bonded by ionic, covalent and metallic forces, the nearest Cd and Te atoms of the host material having a known bond length, the CdTe host material being alloyed with Group II and Group VI atoms that replace a total of about 0.1 of the Cd and Te atoms of the host material so that the alloyed and host atoms are bonded by at least covalent and metallic forces, the alloyed atoms having a bond length with the nearest neighboring host atoms that is less than the known host bond length, the number of bonded alloyed atoms being small compared to the number of bonded host atoms so as not to substantially affect electron conduction and optical properties of the host material, whereby a p type semiconductor volume having a low dislocation density relative to the dislocation density of the CdTe is formed, an n type semiconductor region forming a junction with the volume of the p type semiconductor, and first and second metal electrode means respectively making separate ohmic contacts with the volumes of the low dislocation density p type semiconductor and the n type semiconductor.
Claim 17
Dependent Claim
208 words
A photovoltaic cell comprising a p type CdTe semiconductor formed of tetrahedral structural crystalline host semiconductor material including Cd and Te atoms bonded by ionic, covalent and metallic forces, the nearest Cd and Te atoms of the host material having a known bond length, the CdTe host material being alloyed with Group II and Group VI atoms that replace a total of about 0.1 of the Cd and Te atoms of the host material so that the alloyed and host atoms are bonded by at least covalent and metallic forces, the alloyed atoms having a bond length with the nearest neighboring host atoms that is less than the known host bond length, the number of bonded alloyed atoms being small compared to the number of bonded host atoms so as not to substantially affect electron conduction and optical properties of the host material, whereby a p type semiconductor volume having a low dislocation density relative to the dislocation density of the CdTe is formed, an n type semiconductor region forming a junction with the volume of the p type semiconductor, and first and second metal electrode means respectively making separate ohmic contacts with the volumes of the low dislocation density p type semiconductor and the n type semiconductor.
Claim 18
Dependent Claim
57 words
The photovoltaic cell of claim 14 wherein the Group II atoms are Zn and the Group VI atoms are selected from the group consisting essentially of S and Se, whereby the p type semiconductor volume is selected from the group consisting essentially of Cd.sub.1-x Zn.sub.x Te.sub.1-y Se.sub.y and Cd.sub.1-x Zn.sub.x Te.sub.1-y S.sub.y, where x+y is about 0.1.
Claim 19
Dependent Claim
24 words
The photovoltaic cell of claim 14 wherein the p and n type semiconductors differ from each other, whereby a heterojunction is formed by them.
Claim 20
Dependent Claim
17 words
The photovoltaic cell of claim 14 wherein the p and n type semiconductors are the same compounds.
References Cited (Backward Citations)
US3261726A
Cited
JPS4888027A
Cited
JPS4973686A
Cited
US4400244A
Cited
US4179308A
Cited
EP0045195A2
Cited
US4445965A
Cited
EP0080342A2
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1989-02-03 | 1989-08-05 | 1990-02-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-02-03 | 1993-08-05 | 1994-02-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-02-03 | 1997-08-05 | 1998-02-04 | $7700.00 | Window Closed / Lapsed |