Study On Optoelectric Properties Of ZnO Films Deposited By PLD Method

ZnO is aⅡ-Ⅵwide-band-gap(～3.3eV at room temperature) semiconductor with a hexagonal wurtzite structure.In terms of optoelectronics,its direct band gap and a large exciton banding energy(60meV) should in principle lead to low thresholds for optical gain even at room temperature.Due to the excellent physical and chemical properties,they can be integrated with many semiconductor materials readily.ZnO films also have many realized and potential applications such as surface acoustic wave devices,ultraviolet photodetectors, gas sensors,light emitters,transition layer for GaN and transparent conductors for display, etc.In this work,pure ZnO films were deposited on sapphire,silicon,quartz and nitrided sapphire substrates by PLD method at different temperatures;RHEED,XRD,Hall measurement,transmittance and photoluminescence were used to measure and analyze the structure,the optical and electric properties of films.This work includes two parts as follow:ⅠBy using PLD method,ZnO films with excellent c-axis orientation were made on sapphire substrates at different temperatures of 250℃,350℃,450℃and 550℃.X-ray diffraction,transmittance,Hall measurement,and variable-temperature photoluminescence (PL) are used to characterize the films.In this wook,the effect of deposited temperature and the relationship between crystalline quality and optoelectric propertie of ZnO films were studied.We found that the photoluminescence peak near 3.31eV appeared in low temperature can related to the carrier concentration,related the energy level and may be responsible for intrinsic ZnO conductivity.ⅡBy using PLD method,ZnO films with excellent c-axis orientation were made on silicon,quartz and nitrided sapphire substrates at different temperatures.The stucture and optical properties of ZnO films deposited at different substrates were studied.The influence of substrates nitridation on growth behavior and optical properties of ZnO films were also discussed.RHEED,X-ray diffraction,transmittance,Hall measurement,and photoluminescence method were used to analyze above films which deposited at different conditions.