High responsivity solar blind photodetector based on high Mg content MgZnO film grown via pulsed metal organic chemical vapor deposition

Abstract

Metal-semiconductor-metal (MSM) structured solar blind photodetectors were fabricated based on various Mg content wurtzite MgxZn1−xO epitaxial films grown via pulsed metal organic chemical vapor deposition. The response spectra of the devices showed a peak position that shifts from ∼383nm to 276nm for Mg content, x, between 0.0 and 0.51, covering a wide portion of the ultra-violet spectral region, extending well into the solar blind window. At 10V bias, a large responsivity of ∼1.8×104A/W was obtained at 276nm for a device based on a high Mg content (x=0.51) MgZnO film. To the best of our knowledge, this responsivity is the highest ever reported for a MgZnO based device and its origin is attributed to large internal gain resulting from carrier trapping at the MgZnO/Ni/Au interface. This is confirmed by the presence of an asymmetric Schottky barrier height on the two MSM contacts. Conversely, the response speed of the devices was slow with the 10%–90% rise and fall times measured to be in the millisecond range. The results reported in this work show the realization of high responsivity MgZnO based solar blind photodetectors, providing a significant step in the development of MgZnO alloy based of detector.