%0 Journal Article
%T Ultra-thin crystalline silicon films produced by plasma assisted epitaxial growth on silicon wafers and their transfer to foreign substrates*
%A Moreno M.
%A Cabarrocas P. Roca i
%J EPJ Photovoltaics
%D 2010
%I EDP Sciences
%R 10.1051/epjpv/2010001
%X We have developed a new process to produce ultra-thin crystalline silicon films with thicknesses in the range of 0.1   1 ¦Ìm on flexible substrates. A crystalline silicon wafer was cleaned by SiF4 plasma exposure and without breaking vacuum, an epitaxial film was grown from SiF4, H2 and Ar gas mixtures at low substrate temperature (Tsub ¡Ö 200 ¡ãC) in a standard RF PECVD reactor. We found that H2 dilution is a key parameter for the growth of high quality epitaxial films and modification of the structural composition of the interface with the c-Si wafer, allowing one to switch from a smooth interface at low hydrogen flow rates to a fragile one, composed of hydrogen-rich micro-cavities, at high hydrogen flow rates. This feature can be advantageously used to separate the epitaxial film from the crystalline Si wafer. As a example demonstration, we show that by depositing a metal film followed by a spin-coated polyimide layer and applying a moderate thermal treatment to the stack, the fragile interface breaks down and allows one to obtain an ultrathin crystalline wafer on the flexible polyimide support.
%U http://dx.doi.org/10.1051/epjpv/2010001