Heterojunction bipolar transistor having heterostructure ballasting emitter
US5859447A · kind A · utility
Inventors
Key dates
| Filing date | May 9, 1997 |
| Grant date | Jan 12, 1999 |
| Priority date | — |
| Expiry date | May 9, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10D62/136
Abstract
An HBT device having heterostructure ballasting emitter is disclosed. The heterostructure ballasting emitter includes an n-type emitter setback layer on a base layer and a wide-gap ballasting emitter layer on the setback layer. The heterostructure ballasting emitter is made so that the band gap of the emitter setback layer is equal to or larger than that of the base layer and the band gap of the ballasting emitter layer is larger than that of the emitter setback layer. The heterostructure of the emitter setback layer and the ballasting emitter layer serves as the ballast. By changing the value of the valance offset between the emitter setback layer and the ballasting emitter layer, the temperature dependence of the current gain becomes adjustable. As a consequence, the present invention overcomes hurdles posed by the current gain collapse and a negative differential resistance and improves the use of the HBTs in microwave power applications.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.