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

Abstract

The effect of surface passivation of undoped p-CdTe(100) by (NH4)2Sx treatment was investigated by using photoluminescence (PL), photoconductivity (PC), and x-ray photoelectron spectroscopy (XPS). After sulfur treatment for 2 min, the acceptor bound exciton (A0, 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 the Te 3d core levels, and these additional peaks are related to TeO3 with binding energies of 576.2 and 586.5 eV. After sulfur treatment, while the intensities of the Te 3d core levels decreased gradually, those of the TeO3 peaks 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 CdS formation at the surface of CdTe. These results indicate the sulfur effectively dissociates the native oxides from and neutralizes the dangling bonds at the surface of CdTe.

Obtaining of polycrystalline CdTeO3 by reactive pulse laser deposition

“…Te 3d 5/2 and Te 3d 3/2 peaks in TeO 2 for the sample appear at the binding energies of 575.7 and 586.1 eV, respectively. From deconvoluting the oxide and CdTe peaks no TeO 3 and no elemental Te were found to be present in the film as has been reported in similar works on this material [14]. Two little peaks appear at binding energy of 572.6 and 582.8 eV, which correspond with the 3d 5/2 and 3d 3/2 peaks of Te -Cd bounds.…”

Charge-carrier transport and recombination in heteroepitaxial CdTe

“…Both recombination velocities are relatively high. Chemical treatments, similar to those described in the literature for single-crystal CdTe, 31,32 might be used to reduce recombination velocity at the epitaxial surface. A double heterostructure could also reduce recombination.…”

Windowless CdSe/CdTe Solar Cells with Differentiated Back Contacts: J–V, EQE, and Photocurrent Mapping

“…The annealed and passivated devices exhibit no statistically significant dependence of V oc on W CdSe for either the best-performing devices (Table ) or the broader set of specimens (Figure ). The ammonium sulfide passivation , was generally responsible for 140–170 mV improvement of V oc ; however, only a 100–120 mV increase upon passivation was observed for some of the lower efficiency devices. Short circuit current densities range from 15.3 to 16.5 mA/cm 2 for the highest efficiency devices; all exceed published values for back contact thin film devices. − For the broad set of devices, although J sc exceeds 17 mA/cm 2 for larger W CdSe , the variation with W CdSe is not statistically significant.…”

“…3). The ammonium sulfide passivation 23–24 was generally responsible for 140 mV to 170 mV of V oc ; however, only 100 mV to 120 mV increase upon passivation was observed for some of the lower efficiency devices. Short circuit current densities range from 15.3 mA/cm 2 to 16.5 mA/cm 2 for the highest efficiency devices; all exceed published values for back contact thin film devices 4–8 .…”