通过反应磁控溅射过程中的等离子体发射光谱,研究了制备ZnO薄膜的沉积温度、氧气流量比例R=O2/(O2,+Ar)对Zn和O原子发射光谱的影响,并结合ZnO薄膜的结构和物理性能,探讨了沉积温度在ZnO薄膜生长中的作用.研究结果显示:当R≥0.75%时,Zn的溅射产额随R的增加基本呈线性下降规律.当R介于10%-50%时,氧含量的变化相对平缓,有利于ZnO薄膜生长的稳定性控制.Zn原子发射光谱强度随沉积温度的变化可以分为三个阶段.当沉积温度低于250℃时,发射光谱强度基本保持不变;当沉积温度介于250-550℃时,光谱强度随沉积温度的增加呈线性增加的趋势;当沉积温度大于550℃以后,光谱强度随沉积温度的增加而迅速增加.通过沉积温度的控制可以实现满足或接近化学计量配比的ZnO薄膜的生长,适合高质量ZnO薄膜沉积的温度介于650-800℃,750℃下沉积的ZnO薄膜具有比较低的缺陷密度和明显的室温紫外光致荧光发射.
Using on-line measurement of plasma emission spectra during reactive magnetron sputtering, the growth of ZnO films was studied with the variation of O2 flow and deposition temperature, ranging from room temperature to 750℃. With the structural characterization and measurement of optical properties, we revealed the role of growth temperature and O2 flow in the growth of ZnO film. The results showed that O2 flow was important in determining the sputtering yield of Zn target. When the flow ratio of O2 to Ar +O2 (R)〉0.75 %, the sputtering yield of Zn decreased linearly with increasing O2 flow. When R was in the 10%-50% range, the concentration of oxygen varied slowly, which may be useful for the control of film growth. The intensity of emission spectrum of atomic Zn at 481.3 nm varied with increasing deposition temperature T. When T〈250℃, the intensity was approximately a constant. When 250℃〈T〈550℃, the intensity increased linearly with increasing deposition temperature. When T〉550℃, the intensity increased sharply with increasing deposition temperature. By controlling the deposition temperature, a high-quality film with the composition close to stoichiometric ZnO was fabricated on Si(001) substrate at 750℃ and ultraviolet photoluminescence was detected at room temperature.