To lower the launch cost and prolong the lifetime of a deep space explorer, solar- and astrophysicists and photonics scientists have devoted much time and energy in exploring and developing a compact and low-power-consumption semiconductor-based vacuum ultraviolet (VUV) photodetector. However, the target has not yet been achieved due to the lack of high external quantum efficiency (EQE) VUV photoconductive materials. Here, we found that two-dimensional MgO, obtained via conformal anneal synthesis method, had ultrasensitive photoresponse to VUV light. It can identify an extremely weak VUV signal (0.85 pW), with a high EQE of 1539%. Such ultrasensitive photoresponse is attributed to the high charge-collection efficiency of excited carriers. Our results provide an idea for developing integrated VUV devices with high responsivity and low power consumption, which will prolong the service time and lower the launch cost of a space explorer.
Keywords: MgO; conformal anneal synthesis; photodetector; two-dimensional oxides; vacuum ultraviolet.