Epitaxy of III-Nitrides on β-GaO and Its Vertical Structure LEDs.

β-GaO, characterized with high n-type conductivity, little lattice mismatch with III-Nitrides, high transparency (>80%) in blue, and UVA (400-320 nm) as well as UVB (320-280 nm) regions, has great potential as the substrate for vertical structure blue and especially ultra violet LEDs (light emitting diodes). Large efforts have been made to improve the quality of III-Nitrides epilayers on β-GaO. Furthermore, the fabrication of vertical blue LEDs has been preliminarily realized with the best result that output power reaches to 4.82 W (under a current of 10 A) and internal quantum efficiency (IQE) exceeds 78% by different groups, respectively, while there is nearly no demonstration of UV-LEDs on β-GaO. In this review, with the perspective from materials to devices, we first describe the basic properties, growth method, as well as doping of β-GaO, then introduce in detail the progress in growth of GaN on (1 0 0) and (-2 0 1) β-GaO, followed by the epitaxy of AlGaN on gallium oxide. Finally, the advances in fabrication and performance of vertical structure LED (VLED) are presented.