MgZnO based ultraviolet photodetector with high photoresponsivity achieved by fluorine doping

We report a high-responsivity ultraviolet photodetector fabricated from fluorine doped Mg0.4Zn0.6O thin film grown by molecular beam expitaxy. The doped epitaxial film demonstrates a low resistivity with a carrier concentration of 2.18 × 1017 cm− 3 and mobility of 2.67 cm2/V s− 1 by Van der Pauw Hall measurements. With a further study of a single Ti/Au-MgZnO:F Schottky junction, it is found the device has a lowered barrier height of 0.59-0.64 eV compared with the calculated value. Our photodetector configured with a metal-semiconductor-metal structure with Ti/Au interdigital electrodes exhibits a high photoresonsivity of 80 A/W, nearly 800 times larger than that of undoped sample. This record-high value is attributed to the lowered Schottky barrier as well as reduced barrier thickness thanks to the effective fluorine doping.