Evaluation of Gallium Nitride for Active Microwave Devices.
Technical rept. no. 2 (Annual), 1 Apr 73-31 Mar 74,
UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES ELECTRONIC SCIENCES LAB
Pagination or Media Count:
In designing a GaN structure for pulsed field measurement of the saturated drift velocity, it is desirable to eliminate an inhomogeneous GaN layer near the substrate interface, to reduce cracking due to differential thermal expansion between the sample and the substrate, to reduce surface conduction by maximizing the surface paths between contacts, to microscopically identify regions free of occlusions and to match the impedance of available pulsers. All of these requirements lead to the desire for thick layers of GaN. Using a two-step halide CVD growth method the authors have succeeded in depositing 2-5mm thick single crystal GaN layers on 1 x 2cm sapphire substrates. The crystals are doped 2-4 x 10 to the 18th power per cc n-type by Si contamination during growth. If the authors can now reduce this value an order of magnitude, or compensate the crystals, they should have material from which structures can be made capable of measuring drift velocity into the 10 to the 7th power cmsec range. Modified author abstract
- Solid State Physics