氧分压对磁控溅射ZnO薄膜生长行为和光学特性的影响

采用反应射频磁控溅射方法, 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、透射光谱和室温光致荧光光谱等分析技术, 研究了氧分压对薄膜的表面形貌和光学特性的影响. 研究结果显示: 0.04～0.23Pa的氧分压范围内, ZnO薄膜存在三个不同的生长模式, 薄膜生长模式转变的临界氧分压分别位于0.04～0.08Pa和0.16～0.19Pa之间; 在0.16Pa以下时, ZnO薄膜的表面岛呈+c取向的竹笋状生长; 当氧分压>0.19Pa时, 薄膜的表面岛以-c取向生长为主; ZnO薄膜的折射率、光学带隙宽度以及PL光谱强度均随着氧分压的增大而增大, 氧分压为0.19Pa时, 薄膜的发光峰最窄, 其半峰宽为88meV.

Effect of Oxygen Pressure on the Growth Behavior and Optical Properties of ZnO Films

Using a reactive radio-frequent magnetron sputtering method, high c-axis oriented ZnO films were deposited on Si (001) and quartz substrates under various oxygen partial pressures with a total pressure of 0.3Pa. Atomic force microscope, X-ray diffraction, UV-Visible transmission spectroscope and photoluminescence (PL) were used to study the effect of oxygen pressure on the surface morphology and optical properties of ZnO films. It is found that the films have three different growth modes in the range of oxygen pressure from 0.04Pa to 0.23Pa. The critical pressures for the transition of film growth can be taken at 0.04--0.08Pa and 0.16--0.19Pa, respectively. When the oxygen pressure is lower than 0.16Pa, the film grown along +c axis. When the oxygen pressure exceeds 0.19Pa, grains along -c axis growth are dominant in the films. With the increase of oxygen pressure, the transmittance, refraction index, optical band gap, and PL intensity increase. At the oxygen pressure of 0.19Pa, the film has a narrowest PL spectrum with a full width at half maximum of 88 meV at room temperature.