화학공학소재연구정보센터
Thin Solid Films, Vol.515, No.15, 5828-5832, 2007
Nucleation of CdTe thin films deposited by close-space sublimation under a nitrogen ambient
The early stages of the close-space sublimation growth of CdTe/ITO (indium tin o.cide) at 500 degrees C under 26.7 kPa (200 Torr) of N-2 were investigated, the relatively high pressure being used to slow the growth. Film development was monitored over 60 mins by ex-situ AFM (atomic force microscopy), the growth being controlled by a shutter. The films formed by the 'island' or Volmer-Weber growth mechanism. Developments in the area] island growth rate, the island density and spatial distribution type were explained using growth mechanisms. Significant changes in these phenomena at t >= 10 mins were attributed to a change in growth mechanism from surface migration limited, to a regime in which island coalescence and direct impingement of vapour species on the islands became important. Since the islands are characterised by distinct crystalline facets, this indicates the growth mechanism to be uninterrupted step-flow like addition of material to each island. Arguments are given to relate the final grain size in the films to the density of nuclei that are stable to re-evaporation after t = 10 mins. (C) 2006 Elsevier B.V. All rights reserved.