An experimental and modeling analysis of vapor transport deposition of cadmium telluride

Vapor transport deposition (VTD) was employed for high-rate deposition of CdTe thin film solar absorbers. A detailed model was developed for CdTe deposition that included the role of source conditions, convective mass transport, and deposition chemistry. A Langmuir formulation that was consistent with experimental observations of resublimation was used to describe the surface reaction probability. Comparisons of experiment and model showed very good agreement over a range of operating conditions. The model predicts an optimum operating pressure for VTD, arising from a competition between surface kinetics and dilution of the precursor species. For VTD deposition of CdTe the optimum pressure is in the range of 2-5 Torr. These modeling concepts may be easily extended to VTD of other materials as well. (C) 2004 Elsevier B.V. All rights reserved.