Abstract: The chemical etching of CdTe thin films is one of important techniques in preparation of CdTe solar cells.In this paper,the CdTe thin films were etched with a mixture of nitric-phosphoric acid in water（NP）（HNO₃ 1%,H₃PO₄ 70%,and de-ionized H₂O 29%）.And a Te layer was found on the etched CdTe films by the X-ray diffraction（XRD）measurement.Several types of back-contact layers were then deposited on the etched CdTe thin films to complete the fabrication of CdTe solar cells.From the dark and illuminated I-V and C-V measurements,higher efficiency has been demonstrated for the small area CdTe solar cells of ZnTe/ZnTe:Cu/Ni.And this kind of solar cells shows better performance than those with the other back contacts.The results also imply the close relationship between the device performance and the Te layer formation and Cu diffusion.