图谱分析退火对CdTe多晶薄膜性能影响

Spectral Analysis of the Effect of Annealing on CdTe Polycrystalline Film

对近空间蒸发系统制备的同一CdTe薄膜进行分割并在不同条件下进行退火,通过XRD、SEM、电导温度关系以及XPS等研究退火后薄膜结构,各元素含量分布以及价态变化。结果表明:刚沉积的CdTe薄膜呈立方相,沿(111)明显的择优取向,退火后(111)(220)(311)等峰的强度有不同程度的增强。晶粒长大,晶界减小,降低通过晶界载流子复合概率,降低暗电导激活能,改善电池的并联电阻和漏电流。XPS测试表明样品中存在碲的氧化物,而且随着刻蚀深度的增加氧化物明显减少。通过分析,认为样品中可能存在TeClO2的结构单元,导致薄膜性能的改变。样品表面氧元素含量较多,随着刻蚀深度的增加,氯氧2种元素的含量明显减少,而且氯元素在样品中达到了稳定的分布。

Polycrystalline CdTe thin films were prepared by close-spaced sublimation （CCS） and were annealed in different condition. The thin films were characterized by scanning electron microscopy （SEM）, X-ray diffraction （XRD） and X-ray photoelectron spectroscopy（XPS）. The content distribution and valence state of all elements after annealing were studied. All results show that the as-deposited CdTe thin films are in a cubic phase and have the preferred orientation in （111） direction. After annealing, the peak intensity of （111）, （220）, （311） grows and the crystal grains grow up, while the crystal boundary decreases. So the compound probabilities of current carrier decrease, therefore shunt resistance and drain current are improved. From detailed analysis of X-ray photoelectron data, it is proposed that tellurium oxides present and its content reduces with depth increasing and that there are TeCl2 O building blocks.