Photodetectors Based on Wurtzite MgZnO

Wide band gap semiconductors such as MgxZn1-xO represent an excellent choice for making optical photodetectors and emitters operating in the UV spectral region. High crystal and optical quality MgxZn1-xO thin films were grown epitaxially on c-plane sapphire substrates by plasma-assisted Molecular Beam Epitaxy. ZnO thin films with high crystalline quality, low defect and dislocation densities, and sub-nanometer surface roughness were achieved by applying a low temperature nucleation layer. Resultant epitaxial ZnO films demonstrated excellent structural and morphological properties. By tuning Mg/Zn flux ratio, steep optical absorption edge of the MgxZn1-xO with spectral cutoff wavelength ranging from 278nm to 377nm was demonstrated, corresponding to the mole fraction x ranging from 0 to 0.46. Photoconductive and Schottky barrier MSM PDs with interdigital electrode geometry and active surface area of 1mm2 were fabricated. The I-V characteristics, in dark and under ultraviolet illumination, as well as spectral and temporal responses were characterized at zero-bias and 5V bias conditions