Amorphous-MgGaO Film Combined with Graphene for Vacuum-Ultraviolet Photovoltaic Detector.

Vacuum-ultraviolet (VUV) detector equipped on satellites has extensive application in space exploration and cosmic science. For a VUV detector, a semiconductor material with a sufficiently wide band gap is eagerly desired. In this work, a wide-band gap amorphous-MgGaO (a-MGO) film was epitaxially grown on n-type GaN substrate by atomic layer deposition and a p-i-n-type heterojunction device for VUV detection was constructed with a-MGO film as a photosensitive layer and p-type graphene as a transparent conductive layer. The device exhibits a good spectral selectivity of VUV with photovoltaic response, a high responsivity (2 mA W-1) under zero bias, and an ultrafast response speed (rise and decay time of 0.76 μs and 0.56 ms, respectively) under nanosecond VUV pulse irradiation. This newly developed device shows great potential in VUV detection for space exploration.