RESUMO
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 degrees C, 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.
RESUMO
ZnTe and ZnTe: Cu polycrystalline films were fabricated by means of co-evaporating at room temperature. The relationships between conductivity of the films and temperature were measured. Chemical compositions of ZnTe and ZnTe: Cu polycrystalline films were obtained by using XPS, and the changes of chemical composition before and after anneal were analyzed. The results showed that the conductivity of ZnTe rose linearly with the temperature, and Te was enriched on the margin of every sample's surface; With the rise in temperature, the conductivity of ZnTe: Cu films became abnormal, the oxidization of Te became very obvious and Zn diffused from the bulk to the surface. The composition became more uniform and all peaks became stronger. Carrier concentration caused by CuxTe appeared, resulting in the abnormal relationship between conductivity of the films and temperature.
