反应溅射氧化锌薄膜的结构特点及性质

以金属Zn(纯度为99.99%)作为靶材,采用离子束反应溅射法在玻璃衬底上溅射沉积了一系列ZnO薄膜样品。通过对薄膜样品X射线衍射(XRD)谱的分析,发现尽管溅射条件不同,但是ZnO薄膜只沿(0002)晶面取向生长。衬底温度和溅射气体的氧分压对薄膜沿c轴取向生长有影响,其中衬底温度的影响较明显。溅射过程中发现衬底温度为360℃最适合(0002)晶面的生长,在此温度下溅射获得了完全沿c轴取向生长且衍射峰最强的ZnO薄膜。室温下测量了ZnO薄膜的发射光谱,发现薄膜在紫外区(364nm附近)、蓝绿区(470nm附近)有较强的发光峰,在紫光区(398nm附近)、蓝光区(452nm附近)和红外区(722nm附近)有较弱的发光峰。ZnO薄膜在空气中退火,对薄膜的结构、发光和电学性质都有一定影响。合适的退火温度可以促进薄膜沿c轴的取向生长;退火后ZnO多晶薄膜的晶粒比未退火的略大;退火使部分发光峰的位置发生偏移并使薄膜的发光强度增强;退火使薄膜的电阻率显著增大,薄膜的电阻率随氧分压的增大而增大。

Structure and Properties of ZnO Films Prepared by Ion Beam Reactive Sputtering

ZnO is a very useful and interesting ceramic material,since it exhibits a variety of properties such as semiconductive, photoconductive, piezoelectric and electro-optical behavior. Due to these characteristics, structure, properties and preparation methods of ZnO films have been extensively studied for practical applications. Different from other preparation methods, a series of ZnO films on glass substrate have been prepared by ion beam reactive sputtering with metal Zn (purity 99.99%) as target. X-ray diffraction (XRD) spectra analysis of the ZnO films indicates that the films are single (0002)-oriented growth although preparation condition changed. Temperature of substrate is a key factor on preferential orientation growth of ZnOfilm in (0002) direction. Ratio of Ar/O₂ (sputtering gas) has a little affection on structure of the films. 360℃ is a most adaptive substrate temperature for ZnOfilms single (0002)-oriented growth, and high quality ZnOfilm with absolute c-axis orientation has been successfully achieved at this temperature. Photoluminescence (PL) spectra show that some PLpeaks are very strong at wave band of both ultraviolet (364 nm) and blue-green (470 nm) under excitation of 270 nm, another PLweak peaks appear at violet (398 nm), blue (452 nm) and infrared (722 nm) band. Among the peaks, PLpeak of 470 nm has not been reported up to now. Annealing in air has significant influence on structure, photoluminescence and electric properties of the films. An appropriate annealing temperature can promote single c-axis oriented growth of ZnO films, make crystal grains much bigger, luminescence intensifying and make resistance raising of the ZnO films. 400℃ is a optimum annealing temperature for single (0002)-oriented growth of the ZnO films and enhancing the film's luminescence intensity. Resistance of ZnO films increase with not only pressure of oxygen enlarging, but also substrate temperature raising. After 350℃ annealing in air, ZnO films become insulators. The results indicate the film's PL property has no relationship with its resistance.