Sulphur diffusion in CdTe and the phase diagram of the CdS-CdTe pseudo-binary alloy

The CdS-CdTe system is of interest for thin film heterojunction solar cells, their performance being critically affected by interdiffusion and change of crystallographic phase at the interface during device processing. The diffusion of S in single crystal CdTe at temperatures between 372 and 675 degrees C has been investigated by SIMS. Diffusion has been shown to be dominated by two mechanisms, with activation energies of 1.06 (+/-0.04) and 1.7 (+/-0.2) eV. The CdS-CdTe phase diagram has also been re-examined at temperatures of 700 and 1000 degrees C. Samples were equilibrated at 1000 degrees C, slowly cooled to the required temperature and analysed by X-ray diffraction (XRD) and particle induced X-ray emission (PIXE). The results agree with the previously published phase diagram at these temperatures. (C) 1999 Elsevier Science B.V. All rights reserved.