工作气压对磁控溅射ZnO薄膜结晶特性及生长行为的影响

采用射频反应磁控溅射方法，在Si(001)基片上制备了具有高c轴择优取向的ZnO薄膜.利用原子力显微镜、X射线衍射、透射电子显微镜和透射光谱分析技术，对不同工作气压下合成的ZnO薄膜的表面形貌、微观结构和光学性能进行表征，研究了工作气压对ZnO薄膜的结晶性能以及生长行为的影响.研究结果显示：对于Ar/O₂流量比例接近1∶1的固定比值下，ZnO薄膜的生长行为主要取决于成膜空间中氧的密度，临界工作气压介于0.5—1.0 Pa之间.当工作气压小于临界值时，ZnO薄膜的成核密度较高，且随工作气压的变化明显，ZnO的生长行为受控于氧的密度，属于氧支配的薄膜生长；当工作气压大于临界值以后，ZnO薄膜的成核密度基本保持不变，Zn原子的数量决定薄膜的生长速率；在0.1—5.0 Pa的工作气压范围内，均可获得高度c轴取向的ZnO薄膜，但工作气压的变化改变着ZnO晶粒之间的界面特征和取向关系.随着工作气压的增加，ZnO晶粒之间的界面失配缺陷减少，但平面织构特征逐渐消失，三叉晶界的空洞逐渐扩大，薄膜的密度下降，折射率减小. 关键词： ZnO薄膜 磁控溅射 表面形貌 微观结构 光学性能

Influence of working pressure on the crystallinity and growth behavior of ZnO films deposited by reactive radio-frequency magnetron sputtering

Using the reactive radio-frequency magnetron sputtering method, ZnO films were deposited on Si (001) and quartz substrates at different pressures with a fixed flow ratio of Ar to O₂. The influence of working pressure on the crystallinity and growth behavior were studied with the help of characterization of the morphology, microstructure and optical properties of the films by atomic force microscopy (AFM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and transmittance spectra,respectively. It is found that a critical working pressure can be taken as 0.5—1.0 Pa. With increasing the working pressure from 0.1 Pa up to the critical working pressure, the density of ZnO grains decreases and the films have high c-axis orientation with strong in-plane textured feature. When the working pressure exceeds the critical working pressure, the density of ZnO grains is roughtly a constant and the in-plane textured feature disappears. The influence of working pressure on the refractive index, extinction coefficient and optical energy gap is also discussed in the paper.