Electrical transport properties of III-nitrides

Excellent n-type GaN layers have been grown by all of the major epitaxial techniques: MBE, MOCVD, and HVPE. In this work, we analyze the band conduction in such samples by temperature-dependent Hall-effect measurement and theory, and determine quantitative information on donor and acceptor concentrations, as well as donor activation energies. In HVPE layers it is necessary to take account of a degenerate n-type layer at the GaN/sapphire interface in order to correctly analyze the bulk material. We also investigate hopping conduction, which occurs at low temperatures in conductive material, and at both low and high temperatures in semi-insulating material. Finally, we show by analysis of electron-irradiation data that both the N vacancy and the N interstitial are electrically active, demonstrating donor and acceptor character, respectively.