(AlGa)2O3 solar-blind photodetectors on sapphire with wider bandgap and improved responsivity

Single crystallinity (AlGa)(2)O-3 solar-blind photodetectors are epitaxially grown on sapphire. Oxygen pressure during the growth has a great impact on the Al composition in (AlGa)(2)O-3, which is investigated utilizing X-ray photoelectron spectroscopy and X-ray diffraction measurements. Measured transmittance spectra and responsivity demonstrate that (AlGa)(2)O-3 photodetectors achieve a wider bandgap compared to a Ga2O3 device. An (Al0.12Ga0.88)(2)O-3 device obtains 10 times higher photocurrent Iphoto than a Ga2O3 photodetector. However, as Al composition increases, significant Iphoto degradation is observed in an (Al0.35Ga0.65)(2)O-3 photodetector. Meanwhile, an (Al0.35Ga0.65)(2)O-3 device exhibits the stronger persistent photoconductivity compared to the Ga2O3 control device. Analysis shows that defect states in a bandgap of (AlGa)(2)O-3 might be associated with the performance change in (AlGa)(2)O-3 photodetectors. (C) 2017 Optical Society of America