THE NATURE OF DONOR CONDUCTION IN N-GAN

Single crystal GaN thin films resulting from various deposition techniques are usually dominated by residual donors. To date, the true nature of this donor conduction is not known. Nitrogen vacancies, residual oxygen, and growth defects are cited as potential causes for the residual n-type conduction. In this communication we present the first systematic study of near conduction band edge states in n-type GaN samples deposited over basal plane sapphire substrates using low pressure metal organic chemical vapor deposition. Electron spin resonance, low temperature photoluminescence, and Van der Pauw-Hall measurements were used as the basis for our study. We concluded that the residual n-type conduction in GaN results from a band of delocalized donors.