Quasi-Rheotaxy a new technique to grow large grain thin films on low cost amorphous substrates

Abstract

A new technique of growing large crystalline grain thin films has been developed. This method, that we called Quasi-Rheotaxy, consists in the deposition of thin films on substrates kept at a temperature near their melting point. Several semiconductor thin films which are considered as promising materials for solar photovoltaic conversion such as CdS, CdTe and CuGaInSe2 have been grown by Quasi-Rheotaxy. Low melting point and low vapour pressure metallic elements, such as Sn, Pb, Bi and Tl, have been used as quasi-melted substrates. Stainless steel was used as a base substrate to support the thin layer of the quasi-melted elements which were evaporated in the same vacuum system in which the semiconductor films were prepared. Large crystalline and columnar grains with a size up to 10 μm have been obtained in films grown by Quasi-Rheotaxy. The large crystalline grain thin films, since they are grown on low cost substrates, could be used to build low cost thin film solar cells