Evaluation of Gallium Nitride for Active Microwave Devices.
Abstract
Low temperature photoluminescence results that donors in GaN are relatively shallow, so that low resistivity n-type material at room temperature is easily achieved. However, all 'shallow' acceptors are quite deep, so that low resistivity p-type material is not possible. Thus, high current density, p-n junctions are not feasible. A native shallow donor, probably a simple nitrogen vacancy, is present in all GaN crystals grown, whether by VPE, MOCVD, and from these results, by MBE. It is present in the range 10 to the 18th power to 10 to the 20th power per cu cm. This doping level is much too high for it to be used in the drift region of an IMPATT device. Its value can be reduced by compensation with acceptors. But this also lowers the mobility, leading to an increase of the required electric field to attain saturated drift velocity, thus negating the advantage. The native donor density cannot be reduced by altering growth conditions in VPE, MOCVD or MBE growth. It can, however, be somewhat reduced by ion implantation of N(+) ions, followed by a specified anneal. This, however, leads to a meta-stable situation wherein device degradation seems highly likely. Thus, in spite of its theoretical potential, GaN may not be a good candidate as a material for transit-time-limited, power microwave amplifiers. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1983
- Accession Number
- ADA132988
Entities
People
- M. Gershenzon
Organizations
- University of Southern California