Cryst. Res. Technol. 44, No. 10, 1059 – 1066 (2009) / DOI 10.1002/crat.200900503 © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Deposition of CdTe films under microgravity: Foton M3 mission M. Fiederle* 1 , K. W. Benz 1 , A. Cröll 1 , A. Zappettini 2 , D. Calestani 2 , E. Dieguez 3 , L. Carotenuto 4 , and E. Bassano 4 1 Freiburger Materialforschungszentrum FMF der Albert-Ludwigs-Universität Freiburg, Stefan-Meier-St. 21, 79104 Freiburg, Germany 2 CNR Parma, Instituto Materiali Speciali per Elettronica e Magnetismo IMEM, Parco Area delle Scienze 37A, 43010 Fontani Parma, Italy 3 Universidad Autonoma de Madrid, Departamento de Fisica de Materiales, 28034 Madrid, Spain 4 Telespazio Napoli, Via Gianturco 31, 80146 Napoli, Italy Received 17 August 2009, revised 10 September 2009, accepted 11 September 2009 Published online 25 September 2009 Key words CdTe films, film deposition, microgravity. PACS 81.10.N, 81.20, 81.70.Ha, 85.60.Gz Experiments of deposition of CdTe films have been carried out under microgravity in the Russian Foton M3 mission. The influence of gravity has been studied with these experiments and compared to the results of simulations. The measured deposition rate could be confirmed by the theoretical results for lower temperatures. For higher temperatures the measured thickness of the deposited films was larger compared to the theoretical data. Dedicated to Prof. Wolfgang Neumann on the occasion of his 65 th birthday © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 Introduction Growth of films from the vapour phase for the fabrication of large area x-ray sensors (up to 100 mm substrate diameter) can be carried out in open tube reactors or in closed ampoules[1]. In general, open tube reactors are best suited to achieve uniform layer characteristics over large areas and for growing stacks of layer sequences. However, these features have a prize. Open systems with uniform deposition characteristics have a low yield of material deposition [2]. This is a critical issue because layer structures suitable for x-ray sensors must be as thick as 0.5 mm up to 1.0 mm. Concerning this issue, layer deposition in closed ampoules is a much better choice. The deposition rate and the uniformity of the layer are strongly depending on the presence and the pressure of a carrier gas in an open tube system if the deposition temperature is chosen sufficiently high [3]. Detailed studies of the PVT process are necessary to examine the conditions of Physical Vapour Transport PVT and Chemical Vapour Deposition CVD (flux, composition, formation of regimes, etc.) and to optimize the growth process for commercial needs. These studies have to be complemented by extended modelling of transport and growth processes. Well-defined theoretical background is necessary to understand the experimental configuration and to improve the deposition of films. The focus is the difference between diffusive controlled and kinetic controlled deposition under microgravity [4-6]. This will finally give the required inputs for the modelling of the growth facility on earth. In a European project funded by the European Space Agency an experiment for the deposition of CdTe films was prepared and performed on the Russian Foton M3 mission. An ampoule with four different growth chambers was prepared and placed in a linear temperature profile to measure the deposition rate under microgravity in comparison to 1 g. The experimental data was compared to the results of complex simulation of the deposition of CdTe films. ____________________ * Corresponding author: e-mail: michael.fiederle@fmf.uni-freiburg.de