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