The growth of high quality MgZnO alloy films using plasma-assisted molecular-beam epitaxy and fabrication of ultraviolet detectors based on these films

To develop ZnO-based deep ultraviolet (UV) detectors, we have explored the Mg_xZn_1-xO system as a new approach for the bandgap engineering of ZnO. Mg_xZn_1-xO epitaxial films with different Mg contents (x = 0 to 0.327) were grown on c-sapphire substrates using the radio-frequency (RF) plasma-assisted molecular-beam epitaxy (PA-MBE). We have novel buffer layers designs to improve their crystal qualities and used x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS) and transmittance spectra to characterize the epi-films. Prototypes of UV detectors with the metal-semiconductor-metal (MSM) structure were fabricated and tested, which showed high responsivity and a good signal-to-noise up to three orders of magnitude under 1 V bias, as well as the demonstration of blue-shift tuning of responsivity for Mg_xZn_1-xO-based detectors with Mg doping. These achievements should provide valuable insights and experiences for the Mg_xZn_1-xO-based materials and devices.