Enhanced performance of NiMgO-based ultraviolet photodetector by rapid thermal annealing

•The crystal quality of the Ni1 − xMgxO film was enhanced with rapid thermal annealing.•The optical band gap of Ni1 − xMgxO films increased after rapid thermal annealing.•The dark current of the NiMgO-based ultraviolet photodetector decreased.

Ni1 − xMgxO thin films for metal–semiconductor–metal (MSM) ultraviolet (UV) photodetector were deposited by pulsed laser deposition. The effects of rapid thermal annealing (RTA) on both structural and optical properties of the thin films were studied. After RTA treatment, the Ni1 − xMgxO films showed better crystalline quality with a larger optical band gap. Moreover, the effect of RTA on the current–voltage characteristics of MSM UV photodetector fabricated on the Ni1 − xMgxO thin film was investigated, too. The results revealed that the series of dark current is significantly reduced from 390.50 nA (as-deposited) to 19.96 nA (RTA treated at 1000 °C), which can lead to higher signal-to-noise ratio of the photodetector. Thus the performance of the photodetector was enhanced by RTA to the Ni1 − xMgxO thin films.