RICHARD S HOFFMAN
Social Work in Cleveland, OH
License number
Massachusetts 204842
Issued Date
Aug 10, 1981
Expiration Date
Oct 1, 1994
Type
Licensed Certified Social Worker
Address
Address
Cleveland, OH 44107
Professional information
Using A Critical Composition Grading Technique To Deposit Ingaas Epitaxial Layers On Inp Substrates
US Patent:
6482672, Nov 19, 2002
Filed:
Nov 5, 1998
Appl. No.:
09/186587
Inventors:
Richard W. Hoffman - Bay Village OH
David M. Wilt - Bay Village OH
David M. Wilt - Bay Village OH
Assignee:
Essential Research, Inc. - Cleveland OH
International Classification:
H01L 2120
US Classification:
438 94, 438 93, 438503, 438930, 438936, 117954
Abstract:
A method for growing In Ga As epitaxial layer on a lattice mismatched InP substrate calls for depositing by organo-metallic vapor phase epitaxy, or other epitaxial layer growth technique, a plurality of discreet layers of InAs P over an InP substrate. These layers provide a buffer. Each succeeding buffer layer has a distinct composition which produces less than a critical amount of lattice mismatch relative to the preceding layer. An In Ga As epitaxial layer is grown over the buffer wherein 0. 53x0. 76. A resulting InGaAs structure comprises an InP substrate with at least one InAsP buffer layer sandwiched between the substrate and the InGaAs epitaxial layer. The buffer layer has a critical lattice mismatch of less than 1. 3% relative to the substrate. Additional buffer layers will likewise have a lattice mismatch of no more than 1.
Hydrogen Passivated Heteroepitaxial Iii-V Photovoltaic Devices Grown On Lattice-Mismatched Substrates, And Process
US Patent:
5571339, Nov 5, 1996
Filed:
Apr 17, 1995
Appl. No.:
8/422850
Inventors:
Steven A. Ringel - Columbus OH
Richard W. Hoffman - Bay Village OH
Basab Chatterjee - Columbus OH
Richard W. Hoffman - Bay Village OH
Basab Chatterjee - Columbus OH
Assignee:
The Ohio State Univ. Research Found - Columbus OH
Essential Research Inc. - Cleveland OH
Essential Research Inc. - Cleveland OH
International Classification:
H01L 31068, H01L 310304, H01L 3118
US Classification:
136252
Abstract:
A hydrogen passivated photovoltaic device such as a solar cell comprises a lattice mismatched substrate such as Ge or Si, and a hydrogen passivated heteroepitaxial layer such as InP grown on the substrate. The hydrogen passivated heteroepitaxial III-V photovoltaic device is produced by exposing a sample of a heteroepitaxial III-V material grown on a lattice-mismatched substrate to reactive hydrogen species at elevated temperatures. Reactive hydrogen forms bonds with dangling bonds along dislocations defined in the sample. The electrical activity in the dislocations is passivated as a result of the hydrogenation process.