Growth and morphology control of β-Ga2O3 nanostructures by atmospheric-pressure CVD

Abstract

Growth experiments of monoclinic gallium oxide (β-Ga2O3) nanostructures were performed by the atmospheric-pressure CVD using metal gallium (Ga) beads and water (H2O) as source materials and a Au film as a catalyst in terms of substrate materials, Au film thickness, growth temperature and growth time. Local structure analysis based on transmission electron microscope (TEM) observations and selective area electron diffraction (SAED) measurements revealed the successful growth of single crystalline β-Ga2O3 nanowires (NWs) through vapor-liquid-solid (VLS) growth mechanism. The average diameter of the NWs was changed in the range from ~60 to ~1500nm under the growth conditions picked up in this paper. The critical temperature for the VLS growth using the 30nm-thick Au catalytic film was experimentally estimated to be ~789°C. The diversity of shapes of nanostructures was probably due to the temperature evolution of Au catalytic particle size, the film growth on the NW sides by vapor-solid (VS) growth mechanism, and the epitaxial relation between the substrate and the individual NW. The photoluminescence intensity of the blue band emission at ~490nm relative to that of the ultraviolet band emission at ~360nm became larger with increasing average diameter, suggesting the increase in the native defects formed near the surface region.