Method of producing high reliability heterojunction bipolar transistors
US5162243A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 30, 1991 |
| Grant date | Nov 10, 1992 |
| Priority date | — |
| Expiry date | Aug 30, 2011 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S438/936
Abstract
A technique for producing high reliability GaAsAlGaAs heterojunction bipolar transistors by Molecular Beam Epitaxy with beryllium base doping. Beryllium incorporation and diffusion, during base-layer deposition, is controlled through a combination of reduced substrate temperature and increase As/Ga flux ratio during MBE growth resulting in extremely stable heterojunction bipolar transistor profiles. In addition, graded InGaAs surface layers with non-alloyed refractory metal contacts are shown to significantly improve ohmic reliability to alloyed AuGe contacts. High gain (DC beta) is achieved by the use of an increased substrate temperature during emitter deposition. The HBTs in accordance with the present invention are useful in a number of important microwave applications such as log amps, a/d converters, and sample and hold circuits where high reliability is desired.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.