Synthesis and Characterization of Ge-Doped GaN Crystalline Powders Deposited on Graphite and Silica Glass Substrates

Abstract

Gallium nitride (GaN) powders doped with various amounts of Ge were deposited at 1000 and 1180 °C on graphite and silica glass substrates by a 1-h reaction of NH3 with gaseous Ga2O and GeO, produced by the reaction of carbon with Ga2O3 and GeO2, respectively. The crystallinity of the GaN powders was determined by X-ray diffraction (XRD) and Raman spectroscopy, and their morphology was observed by scanning electron microscopy. The luminescence of the powders was measured at room temperature by cathodoluminescence (CL) to evaluate the quality of the GaN crystals. The influence of Ge-doping of the GaN powders on their crystallinity, morphology, and luminescence is discussed on the basis of the XRD, Raman spectroscopy, and CL results. It is shown that Ge-doped GaN crystals exhibit very high CL intensities accompanied by the elimination of defect-related emission at 430 nm.