April Lynn Brown

US Patent:

54895499, Feb 6, 1996

Filed:

Apr 14, 1994

Appl. No.:

8/223496

Inventors:

Thomas C. Hasenberg - Agoura Hills CA
April S. Brown - Westlake Village CA
Lawrence E. Larson - Santa Monica CA

Assignee:

Hughes Aircraft Company - Los Angeles CA

International Classification:

H01L 2120

US Classification:

437133

Abstract:

High speed Group III-Sb materials are n-doped in a molecular beam epitaxy process by forming a superlattice with n-doped strained layers of a Group III-V compound upon Group III-Sb base layers. The base layers have lower conduction band energy levels than the strained layers, and allow doping electrons from the strained layers to flow into the base layers. The base layers preferably comprise Al. sub. x Ga. sub. 1-x Sb, while the strained layers preferably comprise a binary or ternary compound such as Al. sub. y Ga. sub. 1-y As having a single Group V component, where x and y are each from 0 to 1. The strained layers can be n-doped with silicon or tin, which would produce p-type doping if added directly to the base layers.

US Patent:

54204429, May 30, 1995

Filed:

Apr 5, 1994

Appl. No.:

8/223373

Inventors:

Thomas C. Hasenberg - Agoura Hills CA
April S. Brown - Westlake Village CA
Lawrence E. Larson - Santa Monica CA

Assignee:

Hughes Aircraft Company - Los Angeles CA

International Classification:

H01L 2980
H01L 29207

US Classification:

257 22

Abstract:

High speed Group III-Sb materials are n-doped in a molecular beam epitaxy process by forming a superlattice with n-doped strained layers of a Group III-V compound upon Group III-Sb base layers. The base layers have lower conduction band energy levels than the strained layers, and allow doping electrons from the strained layers to flow into the base layers. The base layers preferably comprise Al. sub. x Ga. sub. 1-x Sb, while the strained layers preferably comprise a binary or ternary compound such as Al. sub. y Ga. sub. 1-y As having a single Group V component, where x and y are each from 0 to 1. The strained layers can be n-doped with silicon or tin, which would produce p-type doping if added directly to the base layers.

US Patent:

53228081, Jun 21, 1994

Filed:

Feb 19, 1993

Appl. No.:

8/020095

Inventors:

April S. Brown - Thousand Oaks CA
Joseph A. Henige - Thousand Oaks CA
Mark Lui - Thousand Oaks CA
Loi Nguyen - Thousand Oaks CA
Robert A. Metzger - Thousand Oaks CA
William E. Stanchina - Thousand Oaks CA

Assignee:

Hughes Aircraft Company - Los Angeles CA

International Classification:

H01L 21265

US Classification:

437 40

Abstract:

A donor layer (17) including an undoped wide bandgap material (14) and an n-type dopant (16) is deposited on a substrate (12) by molecular beam epitaxy (MBE) at a first temperature which is high enough for optimal growth of the donor layer (17). The dopant (16) is silicon or another material which exhibits surface segregation in the wide bandgap material (14) at the first temperature. An undoped spacer layer (18) of the wide bandgap material is deposited on the donor layer (17) at a second temperature which is sufficiently lower than the first temperature that surface segregation of the dopant material from the donor layer (17) into the spacer layer (18) is substantially suppressed. A channel layer (20) of a narrow bandgap material is formed on the spacer layer (18) at a third temperature which is higher than the second temperature and selected for optimal growth of the channel layer (20). The spacer layer (18) is substantially undoped, and the low temperature growth and reduction of donor movement reduces ionized impurity scattering in the channel layer (20).