Effect of hydrogen peroxide pretreatment on ZnO-based metal–semiconductor–metal ultraviolet photodetectors deposited using plasma-enhanced atomic layer deposition

In this study, zinc oxide (ZnO) films were deposited on sapphire substrates using a plasma-enhanced atomic layer deposition system. Prior to deposition, the substrates were treated with hydrogen peroxide (H2O2) in order to increase nucleation on the initial sapphire surface and, thus, enhance the quality of deposited ZnO films. Furthermore, x-ray diffraction spectroscopy measurements indicated that the crystallinity of ZnO films was considerably enhanced by H2O2 pretreatment, with the strongest (002) diffraction peak occurring for the film pretreated with H2O2 for 60 min. X-ray photoelectron spectroscopy also was used, and the results indicated that a high number of Zn–O bonds was generated in ZnO films pretreated appropriately with H2O2. The ZnO film deposited on a sapphire substrate with H2O2 pretreatment for 60 min was applied to metal–semiconductor–metal ultraviolet photodetectors (MSM-UPDs) as an active layer. The fabricated ZnO MSM-UPDs showed improvements in dark current and ultraviolet–visible rejection ratios (0.27 μA and 1.06 × 103, respectively) compared to traditional devices.