Electronic and optical characteristics of an m-plane GaN single crystal grown by hydride vapor phase epitaxy on a GaN seed synthesized by the ammonothermal method using an acidic mineralizer

Fundamental electronic and optical properties of a low-resistivity m-plane GaN single crystal, which was grown by hydride vapor phase epitaxy on a bulk GaN seed crystal synthesized by the ammonothermal method in supercritical ammonia using an acidic mineralizer, were investigated. The threading dislocation and basal-plane staking-fault densities of the crystal were around 10(4) cm(-2) and less than 10(0) cm(-1), respectively. Oxygen doping achieved a high electron concentration of 4 x 10(18) cm(-3) at room temperature. Accordingly, a photoluminescence (PL) band originating from the recombination of hot carriers was observed at low temperatures, even under weak excitation conditions. The simultaneous realization of low-level incorporation of Ga vacancies (VGa) less than 10(16) cm(-3) was confirmed by using the positron annihilation technique. Consistent with our long-standing claim that VGa complexes are the major nonradiative recombination centers in GaN, the fast-component PL lifetime of the near-band-edge emission at room temperature longer than 2 ns was achieved. (C) 2016 The Japan Society of Applied Physics