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

Growth experiments of monoclinic gallium oxide (beta-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 beta-Ga2O3 nanowires (NWs) through vapor-liquid-solid (VLS) growth mechanism. The average diameter of the NWs was changed in the range from similar to 60 to similar to 1500 nm under the growth conditions picked up in this paper. The critical temperature for the VLS growth using the 30 nm-thick Au catalytic film was experimentally estimated to be similar to 789 degrees 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 similar to 490 nm relative to that of the ultraviolet band emission at similar to 360 nm became larger with increasing average diameter, suggesting the increase in the native defects formed near the surface region. (C) 2016 Published by Elsevier B.V.