CdTe太阳电池背接触层的XPS研究

采用共蒸发法在不同条件下制备了ZnTe和ZnTe∶Cu多晶薄膜，通过XRD和XPS研究了它们的结构和各元素的浓度分布。结果表明，不同衬底温度下沉积的薄膜，结构无明显变化，利用XPS溅射剖析获得了薄膜中各成分浓度随溅射时间变化的分布图，发现不同条件下制备的薄膜，溅射速率不同，各成分随溅射时间的变化也不相同。薄膜中Cu的浓度随溅射时间增加而快速增加，并达到一极大值，然后快速下降。根据Cu浓度的变化研究了ZnTe层对Cu原子的阻挡作用，通过对Cu浓度随时间变化分布图的比较，作者认为，用70 ℃制备ZnTe，而后在常温下制备ZnTe∶Cu的复合膜作为CdTe太阳电池的背接触层，能有效阻挡Cu原子的扩散，提高电池效率。

Study on Back Contact Layer of CdTe Solar Cell by XPS

ZnTe and ZnTe∶Cu polycrystalline films were fabricated by means of co-evaporating at room temperature. The sturcture and distribution of various elements were studied by XPS and XRD. The XRD results show that the phase structure of the films deposited at different substrate temperature almost remains unchanged, XPS analysis shows that the compositional dependence of sputtering time is different for the films deposited at different deposition rate. The distribution of Cu in the film grows with the increase in the sputtering time, and reaches a maximum, then falls down rapidly. According to the transformation of the distribution of Cu we excogitated how to prevent Cu diffusion in ZnTe films. Considering Cu as a function of time, ZnTe films were first deposited at the substrate temperature of 70 ℃, and then ZnTe∶Cu films were deposited at room temperature, effectively preventing the diffusion of Cu atom, and thus improving the efficiency of CdTe solar cells.