Bipolar transistor with graded base layer
US7115466B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 20, 2005 |
| Grant date | Oct 3, 2006 |
| Priority date | — |
| Expiry date | Feb 6, 2025 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10D62/8503
Abstract
A semiconductor material which has a high carbon dopant concentration includes gallium, indium, arsenic and nitrogen. The disclosed semiconductor materials have a low sheet resistivity because of the high carbon dopant concentrations obtained. The material can be the base layer of gallium arsenide-based heterojunction bipolar transistors and can be lattice-matched to gallium arsenide emitter and/or collector layers by controlling concentrations of indium and nitrogen in the base layer. The base layer can have a graded band gap that is formed by changing the flow rates during deposition of III and V additive elements employed to reduce band gap relative to different III–V elements that represent the bulk of the layer. The flow rates of the III and V additive elements maintain an essentially constant doping-mobility product value during deposition and can be regulated to obtain pre-selected base-emitter voltages at junctions within a resulting transistor.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.