COMPENSATION OF N-TYPE GAN

Compensation in Se-doped II-type GaN prepared by atmospheric pressure metalorganic vapor phase epitaxy was studied. Hydrogen selenide was th e dopant source. The carrier concentration is linearly proportional to the H2Se pressure for low partial pressures and proportional to the c ube root at high partial pressures. Carrier concentrations as high as 6x10(19) cm(-3) at 295 K were achieved. From Hall-effect measurements, the Se-doped GaN was shown to be highly compensated even for heavily Ir-type material. The defects responsible for the compensation were in vestigated using low-temperature photoluminescence. A strong acceptor- related transition at 3.447 eV at 15 K was observed in the heavily dop ed layer. The observed doping dependence of Se in GaN is attributed to compensation by triply charged vacancies which is consistent with rec ent theoretical calculations on defect formation in it-type material. (C) 1996 American Institute of Physics.