Growth and characterization of beta-Ga_2O_3 single crystals as transparent conductive substrates for GaN

摘要

Large size single crystals of β-Ga_2O_3 with 1 inch in diameter have been grown by the floating zone technique. The stable growth conditions have been determined by the examination of the crystal structure. Wafers have been cut and fine polished in the (100), (010) and (001) planes. These were highly transparent in the visible and near UV, as well as electrically conductive, indicating the potential use of β-Ga_2O_3 as a substrate for optoelectic devices operating in the visibleear UV and with vertical current flow. Epitaxial growth of nitride compounds by the metalorganic vapor phase epitaxy (MOVPE) technique is demonstrated on β-Ga_2O_s single crystal substrates. High-quality (0001) GaN epi-layers with a narrow bandedge luminescence are obtained using a low temperature conductive buffer layer. InGaN multi-quantum well (MQW) structures were also successfully grown. The first blue light-emitting diode (LED) on β-Ga_2O_3 with vertical current injection is demonstrated.