Surface acoustic wave device, substrate therefor and method of manufacturing the substrate
US6342748B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 1, 1999 |
| Grant date | Jan 29, 2002 |
| Priority date | — |
| Expiry date | Nov 1, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H9/02543
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A sapphire single crystal wafer 11 having a diameter not less than two inches and having an off-angled surface which is obtained by rotating an R (1-102) surface about an axis in a negative direction by a given off-angle not less than 2° is introduced in a CVD apparatus. While the sapphire substrate is kept at a temperature of about 950° C., a buffer layer made of gallium nitride or aluminum-gallium nitride is first deposited with an average thickness of 0.1-0.2 &mgr;m, and then an aluminum nitride single crystal layer is deposited with an average thickness not less than 2 &mgr;m. The thus obtained aluminum nitride single crystal layer does not have a significant amount of cracks, has an excellent piezoelectric property, and has a high propagating velocity.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.