MOCVD法制备Cu掺杂ZnO薄膜

摘要

通过金属有机物化学气相沉积(MOCVD)设备,在c-Al2 03衬底上生长本征和Cu掺杂ZnO( ZnO∶ Cu)薄膜.X射线衍射(XRD)谱观察到未掺杂的ZnO和ZnO∶ Cu样品都呈现出较好的c轴择优取向生长.X射线光电子能谱(XPS)表明Cu已掺入到ZnO薄膜中.利用光致发光(PL)测试对本征ZnO和ZnO∶ Cu进行室温和低温PL测试,在ZnO∶ Cu样品的低温PL谱中观察到一个强度很强、范围很广的蓝紫光发射峰(Blue-violet 发射峰,BV发射峰),范围在2.8～3.3 eV之间,又进一步通过变温PL测试发现随着温度的升高,BV发射峰峰位发生红移,且80 K时BV发射峰高能边出现自由电子向受主能级(eA0)的跃迁发光,并计算了Cu受主离化能.%Un-doped and Cu-doped ZnO thin films were grown on c-Al2O3 substrate by metalorganic chemical vapor deposition (MOCVD) system. The way of changing the temperature of Cu(tmhd)2 source bottle was used to change the saturated vapor pressure of Cu ( tmhd ) 2, in the meantime to change the quantity of Cu (tmhd) 2 carried into the the reaction chamber. Then the content of Cu in ZnO films was tested to study the effects of Cu doping on the luminescent properties of ZnO, and explore the process technique and condition of controlling Cu valence in ZnO films. X-ray diffraction (XRD) show un-doped ZnO and ZnO: Cu samples have good c-axis preferred orientation growth. The Cu content of these samples were measured by X-ray photoelec-tron spectroscopy (XPS). The content of Cu in ZnO films were not increased when the Cu(tmhd)2 source temperature was increased, which indicated that increasing the Cu (tmhd) 2 source temperature did not lead to any increase of the Cu-doping level, and the solubility of Cu ions in ZnO is quite low. Low-temperature photo-luminescence (PL) measurements show a strong and broad blue-violet (BV) light emission peak ranging from 2.8 to 3. 3 eV, which could be assigned to donor-acceptor pair (DAP) recombination (between unknown shallow donor level and Cu-related acceptor level). Temperature dependent PL show a red-shift of the BV emission with increasing the temperature from 10 to 180 K, and a new weak shoulder peak appearing at BV emission's high-energy side at 80 K, which could be assigned to eA0. Moreover, the decrease of Cu content in ZnO: Cu film resulted in quenching the intensity of BV emission red-shift of BV emission's peak position. This phenomenon is interesting and rarely reported in the previous works. However, we still need further study to clarify that if it is the electron transition between Zn;-related donor energy level and valence band that causes the BV emission.