氧压与ZnO薄膜发光特性的关系研究

Effects of Oxygen Pressure on Optical Properties of ZnO Thin Films

在不同的环境氧压下用脉冲激光沉积方法在Si(111)衬底上生长了ZnO薄膜,以325 nm He-Cd激光器为激发源获得了薄膜的荧光光谱以研究其发光特性,用X射线衍射仪(XRD)和原子力显微镜(AFM)研究了薄膜的晶体结构和表面形貌,结果表明氧压在20 Pa和50Pa之间制备的ZnO薄膜具有良好的紫外发光特性和较好的晶体质量。分析了ZnO薄膜的发光机理,认为薄膜紫外峰源自自由激子复合发光,绿光峰的发光机制与锌位氧OZn关系密切,氧空位是蓝光发射的重要原因。

ZnO thin films were grown on Si （111） substrates with pulsed laser deposition （PLD） method at various oxygen pressures and their structural and optical properties were investaged. The optical properties of the films were studied by analyzing the photoluminescence spectra gained by using a 325 nm He-Cd laser as the excitaton source. The structural and morphological properties of the films were investigated by XRD and AFM measurements, respectively. The results suggest that films grown under the oxygen pressure of 20-50 Pa have excellent UV emission and high-quality crystallinity. The analysis of PL spectra indicates that UV emission is due to excitonic combination, the green band is due to the replacement of Zn in the crystal lattice for O and the blue band is due to the O vacancies.