Synthesis and characterization of Zn-doped GaN crystals by simultaneous carbothermal reduction and nitridation of Ga 2O 3 and ZnO

Abstract

GaN powders doped with varying amounts of Zn were deposited on silica glass substrates at 1160 °C by reaction for 1 h of NH 3 with gaseous Ga 2O and Zn. These precursor gases were produced by reaction of C with Ga 2O 3 and ZnO, respectively, called carbothermal reduction and nitridation (CRN). For comparison, Zn-doped GaN powders were produced at 1160 °C by direct nitridation (DN) of ZnO/Ga 2O 3 and ZnGa 2O 4 powders with NH 3. Zn-doped GaN single crystals of 1×0.5 mm 2 in size were grown in a silica glass crucible by the CRN method. The crystallinity of the GaN powders was determined by X-ray diffraction and their morphology was observed by scanning electron microscopy. The concentrations of O and Zn in the GaN powders were determined by the combustion and inductively coupled plasma methods. In-depth profiles of the O, H, and Zn concentrations in the GaN single crystals were determined by secondary ion mass spectroscopy. Cathodoluminescence (CL) observation of the GaN powders was performed to evaluate their quality. It is revealed that, compared with the powders prepared by DN, Zn-doped GaN powders produced by CRN exhibit very high CL intensities at 460 nm due to the presence of Zn.