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 Ni-1 (-) 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 Ni-1 - 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 degrees 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 Ni-1 (-) xMgxO thin films. (C) 2014 Elsevier B. V. All rights reserved.