Improvement of crystallinity of GaN layers grown using Ga2O vapor synthesized from liquid Ga and H2O vapor

Abstract

Growth methods using Ga2O vapor allow long-term growth of bulk GaN crystals. Ga2O vapor is generated by the reduction of Ga2O3 powder with H2 gas (Ga2O3–H2 process) or by the oxidation of liquid Ga with H2O vapor (Ga–H2O process). We investigated the dependence of the properties of grown GaN layers on the synthesis of Ga2O. In the Ga–H2O process, the polycrystal density and full width at half maximum (FWHM) GaN(0002) X-ray rocking curves (XRC) at a high growth rate were lower than those in the Ga2O3–H2 process, and a GaN layer with FWHM of 99 arcsec and growth rate of 216 µm/h was obtained. A low H2O partial pressure in the growth zone improved crystallinity in the Ga–H2O process, realized by the high efficiency of conversion from liquid Ga to Ga2O vapor. We concluded that using Ga2O vapor in the Ga–H2O process has the potential for obtaining higher crystallinity with high growth rate.