Optical and Electrical Properties of Ga-Doped ZnO Single Crystalline Films Grown on MgAl[sub 2]O[sub 4](111) by Low Temperature Hydrothermal Synthesis

Single crystalline gallium-doped ZnO films have been hydrothermally grown at using a ZnO seed layer on (111) substrates. High resolution X-ray diffraction showed an epitaxial relationship between the ZnO single crystalline film and the spinel substrate with an out-of-plane orientation of and an in-plane orientation of and . The effects of the doping concentration as well as the postannealing treatments on the electrical and optical properties were examined. After thermal treatment, the carrier concentration in the 2.48% Ga-doped ZnO films was 2 orders of magnitude higher at with a carrier mobility of . The blueshift of the optical bandgap was also observed from the photoluminescence and optical absorption measurements as the doping concentration increased. This can be explained in the framework of the induced stress and Burstein–Moss effects at high carrier concentration.