The growth of CDTe thin film by close space sublimation system

Abstract

The effects of source and substrate temperature, ambient gas pressure and the separation between source and substrate on the growth rate of CdTe using the close space sublimation (CSS) system have been investigated. The growth rate increased as the source temperature increased with an activation energy of 1.9 eV and it was constant and independent of the substrate temperature, up to some breakpoint temperature, above which the rate decreased rapidly to zero. Free sublimation and transport is involved at low pressures such as 7.5 × 10-5 mbar, whereas diffusion-limited transport was involved at pressures of 2 and 6 mbar of N2. The growth rate increased as the separation between the source and the substrate decreased. The film's grain size increased from <1 μm at 335 °C to more than 2.5 μm at above 445 °C. Analysis of the XRD traces indicated that the films grown at 335 °C were a highly preferred (111) orientation and the (111) texture coefficient reduced when the substrate temperature increased. © 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.