Mechanism of radiative recombination in acceptor-doped bulk GaN crystals

Optical and electrical properties of acceptor-doped bulk GaN crystals are d iscussed. Though introducing Zn and Ca to bulk GaN does riot Significantly change electron concentration, it results in the appearance of a blue photo luminescence band accompanying-the relatively strong yellow band usually pr esent. Highly resistive GaN:Mg crystals are obtained when high amount of Mg is introduced to the Ga melt during high-pressure synthesis. Change of ele ctrical properties of Mg-doped bulk crystals is accompanied by the appearan ce of a strong blue emission of GaN similar to that in Ca- and Zn-doped cry stals. Optically detected magnetic resonance investigations indicate a mult i-band character of this blue emission and suggest possible mechanism of co mpensation in acceptor-doped bulk GaN. (C) 1999 Elsevier Science B.V. All r ights reserved.