Epitaxial wafer for heterojunction type field effect transistor
US9111839B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 15, 2013 |
| Grant date | Aug 18, 2015 |
| Priority date | — |
| Expiry date | Jan 15, 2033 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10D62/8503
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
An epitaxial wafer for a heterojunction type FET includes an AlN primary layer, a stepwisely composition-graded buffer layer structure, a superlattice buffer layer structure, a GaN channel layer, and a nitride semiconductor electron supply layer, which are sequentially provided on a Si substrate, the stepwisely composition-graded buffer layer structure including a plurality of AlGaN buffer layers provided on each other such that an Al composition ratio is sequentially reduced, an uppermost layer thereof having a composition of AlxGa1−xN (0<x), a plurality of sets of an AlyGa1−yN (y≦1) superlattice constituting layer and an AlzGa1−zN (0<z<y) superlattice constituting layer being provided on each other alternately starting from one of the AlyGa1−yN superlattice constituting layer and the AlzGa1−zN superlattice constituting layer in the superlattice buffer layer structure, the AlxGa1−xN buffer layer and the AlzGa1−zN superlattice constituting layer satisfying x−0.05≦z≦x+0.05.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.