Heterojunction bipolar transistor having an emitter region with a band gap greater than that of a base region
US4768074A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 13, 1987 |
| Grant date | Aug 30, 1988 |
| Priority date | — |
| Expiry date | Oct 13, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10D10/821
Abstract
A heterojunction bipolar transistor comprises a base region of a first conductivity type formed of a first kind of semiconductor material, an emitter region of a second conductivity type formed of a second kind of semiconductor material which has a band gap greater than that of the first kind of semiconductor material and a smaller electron affinity, a transition region formed between the base region and the emitter region, and a collector region formed adjacent to the base region. The transition region is formed of a plurality of semiconductor layers such that band gaps sequentially increase in a stepped fashion from the semiconductor layer adjacent to the base region toward the semiconductor layer adjacent to the emitter region. The transition region is formed of a semiconductor material having an intermediate composition between the composition of the first kind of semiconductor material and that of the second kind of semiconductor material.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.