Mix-phase MgZnO thin film was fabricated on the c-plane sapphire substrate (Mg0.4Zn0.6O target) under high laser energy density condition by the PLD method. The internal quantum efficiency of the detector based on the mix-phase MgZnO thin film at 230 nm deep UV light reached 86% at 40 V bias voltage. And the Iuv(230 nm)/I dark ratio of the MgZnO detector reached 864 at 40 V bias voltage, which is mainly caused by both the higher internal gain of the detector at deep UV light and its smaller I dark . The high internal gain of the detector is mainly due to the higher density of interfaces between the different structure of MgZnO grains in the mix-phase MgZnO thin film, which is caused by the higher laser energy density deposition condition certified by contrast experiments. The small I dark of the detector is mainly caused by the higher barriers in the mix-phase MgZnO thin film and more cubic MgZnO in the mix-phase MgZnO thin film, and higher laser energy density deposition condition and O-rich c-plane sapphire substrate surface are key factors, which also agree with the contrast experiments results. So when the mix-phase MgZnO thin film that is constituted by both a small number of narrower band gap hexagonal MgZnO and a large number of wide band gap cubic MgZnO is used in the deep UV detector, and the difference in band gaps between different structures of MgZnO is relatively higher, a higher signal/noise ratio of the device at 230 nm deep UV light is gained, which is meaningful for developing high-performance deep UV detection technology.

No abstract