Effects of Substrate Bias Voltage on Structural and Optical Properties of Co-Sputtered (AlxGa1-x)2O3 Films

Doping of [3-Ga2O3 with Al atoms provides an effective approach for further enlargement of the energy bandgap, and enhanced detection in the deep ultraviolet region. Although Al-doped [3-Ga2O3 films have been prepared with various methods, challenges remain in the adjustment of crystal quality to obtain superior properties. In this paper, (AlxGa1-x)(2)O-3(denoted as AGO) films were deposited by magnetron co-sputtering at different bias voltages and annealed at 900 degrees C in air. The dependence of the crystal structure, morphology, and optical properties of the films on bias voltage was investigated. The AGO films exhibit a preferred orientation in the (2 01) plane at various biases, as evidenced by the x-ray diffraction measurements. The films with various bias voltages yield higher crystal quality with optical bandgap of about 5.0 eV. In addition, the AGO films demonstrate 95% absolute average transmittance in the UV-Vis wavelength range. This method thus opens a new way for controlling the quality and properties of AGO films with bias.