Heteroepitaxial Growth of Silicon and Germanium Thin Films on Flexible Metal Substrate by Magnetron Sputtering

High mobility single-crystalline-like Ge thin films have been demonstrated on inexpensive polycrystalline metallic substrates buffered with oxide buffer layer. Doped films of p-type and n-type were fabricated using radio frequency magnetron sputtering on flexible epitaxial templates produced by ion beam assisted deposition (IBAD). Ideal conditions for fabricating p-type and n-type Ge thin films have been optimized based on their structure and Hall mobility. As defect density in Ge is directly related to the CeO2 buffer, the effect of CeO2 layer thickness and quality has been evaluated. A structural design of a p-i-n junction is proposed for solar cells on our flexible substrate based on electrical and crystal properties of Si and Ge thin films fabricated. In order to achieve an efficient harvesting of photo-generated free carriers, fabrication of substrates terminated with epitaxial conductive layers is studied.