High-resistivity GaN Research Articles

Study of Traps in GaN by Thermally-Stimulated Current

ABSTRACTIn this paper we employed the TSC method to investigate the traps in GaN. The measured sample was a M-S-M UV-detector of high-resistance GaN on sapphire grown by LP-MOCVD. The relation of dark conductance to temperature clearly showed three major donor levels at 0.019, 0.13 and 0.74eV respectively. TSC measurements from 60 to 380K indicated that there were at least 11 traps in the GaN material. The active energy of those traps were 0.15, 0.19, 0.25, 0.28, 0.33, 0.39, 0.47, 0.55, 0.60, 0.63 and 0.67eV. The range of trap density is from 6 × l014cm-3 to 2 × l018cm-3. By comparing TSC spectrum to dark current, we consider there are at least 4 hole traps in the measured range with energy of 0.25, 0.28, 0.33 and 0.39eV. The illumination time effect was studied and discussed.

Microwave performance of GaN MESFETs

GaN MESFETs have been fabricated with a 0.25 mu m thick channel on a high resistivity GaN layer grown by metal organic vapour phase epitaxy. These devices have a transconductance of 20 mS/mm. For a 0.7 mu m gate length device, the measured f/sub T/ and f/sub max/ were 8 and 17 GHz, respectively.