Performance enhancement of a ZnMgO film UV photodetector by HF solution treatment

Oxygen adsorption and desorption processes can strongly slow down the response speed of ZnO-based ultraviolet photodetectors. Surface passivation of ZnO-based films is a common method to increase the response speed, but the effect of the traditional passivation technology is usually not very obvious, and often accompanies a decrease in responsivity. Herein we propose a new method to overcome this problem: treating ZnMgO UV photodetectors with HF solution. Interestingly, after treatment with HF solution, the 90–10% decay time of the device is decreased by more than one order of magnitude (from 4.6 ms to 0.34 ms), which can be attributed to the enhancement of the oxygen adsorption speed on the surface of ZnMgO due to the F-modified surface. Moreover, the dark current is decreased from 0.7 pA to 0.4 pA at a bias of 10 V and the responsivity is increased from 145 A W−1 to 326 A W−1. Thus, chemical treatment with HF solution should be a useful and effective method for improving the performance of ZnMgO UV photodetectors.