Intrinsic defects are known to control the electronic properties of CuInSe_2 and its alloys. Recent investigations have shown that inadvertent modification of native defects has been responsible for many improvements in the device performance. This paper examines some chemical and electrochemical surface treatments to deliberately induce changes in the defect composition at the surface of CuInSe_2 alloys. Photocurrent spectral response is used to diagnose and compare the surface quality of the films. The results are interpreted tems of intrinsic defect model. A loss of short wavelength spectral response indicates the presence of a defective surface layer. Specific chemical treatments can dramatically enhance the short wavelength response and enhance device performance. Eectrochemical treatments can lead to a range of surface configurations depending on the applied potential and reduction time. The results have significant implications for devices fabricated with low-cost deposition methods.
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