Effect of surface oxygen vacancy defects on the performance of ZnO quantum dots ultraviolet photodetector*
Hongyu Ma, Kewei Liu, Zhen Cheng, Zhiyao Zheng, Yinzhe Liu, Peixuan Zhang, Xing Chen, Deming Liu, Lei Liu, Dezhen Shen
Abstract
The slower response speed is the main problem in the application of ZnO quantum dots (QDs) photodetector, which has been commonly attributed to the presence of excess oxygen vacancy defects and oxygen adsorption/desorption processes. However, the detailed mechanism is still not very clear. Herein, the properties of ZnO QDs and their photodetectors with different amounts of oxygen vacancy (V O ) defects controlled by hydrogen peroxide (H 2 O 2 ) solution treatment have been investigated. After H 2 O 2 solution treatment, V O concentration of ZnO QDs decreased. The H 2 O 2 solution-treated device has a higher photocurrent and a lower dark current. Meanwhile, with the increase in V O concentration of ZnO QDs, the response speed of the device has been improved due to the increase of oxygen adsorption/desorption rate. More interestingly, the response speed of the device became less sensitive to temperature and oxygen concentration with the increase of V O defects. The findings in this work clarify that the surface V O defects of ZnO QDs could enhance the photoresponse speed, which is helpful for sensor designing.