Surface passivation by sulfur treatment of undoped p-CdTe(100)

The effect of surface passivation of undoped p-CdTe(100) by (NH4)(2)S-x tre atment was investigated by using photoluminescence (PL), photoconductivity (PC), and x-ray photoelectron spectroscopy (XPS). After sulfur treatment fo r 2 min, the acceptor bound exciton (A(0), X) peak increases greatly in the PL spectrum, and the minority-carrier lifetime of CdTe becomes the longest value in the PC measurement. The XPS spectrum for untreated CdTe shows the additional peaks on the right side of two main Te peaks corresponding to t he Te 3d core levels, and these additional peaks are related to TeO3 with b inding energies of 576.2 and 586.5 eV. After sulfur treatment, while the in tensities of the Te 3d core levels decreased gradually, those of the TeO3 p eaks disappear. In addition, the S 2p core-level spectra for sulfur-treated CdTe show the peaks at the 161.7 and 162.8 eV, which are attributed to a C dS formation at the surface of CdTe. These results indicate the sulfur effe ctively dissociates the native oxides from and neutralizes the dangling bon ds at the surface of CdTe. (C) 2000 American Institute of Physics. [S0021-8 979(00)00816-1].