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 VUV detector, a semiconductor material with 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 photosensitive layer and p-type graphene as 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 time of 4.98 μs and decay time of 1 ms) under nanosecond VUV pulse irradiation. This newly developed device shows great potential in VUV detection for space exploration.