Growth and Characterization of Poly-SiGe Prepared by Reactive Thermal CVD

Abstract

ABSTRACTWe have prepared poly-Si1-xGex thin films with different germanium contents (Ge=5%∼40%) by reactive thermal CVD. In this study, the Ge content was controlled by varying the source gases GeF4 flow rate at a fixed Si2H6 flow rate. The effects of GeF4 flow rate on growth rate, film crystallinity, and electrical properties were investigated. The films were always polycrystalline when GeF4 was introduced even in a small amount, while only amorphous film deposited without GeF4. With an increase in GeF4 flow rate, Ge content and conductivity of the films increased and its activation energy decreased. When GeF4 flow rate over a certain value, the growth rate decrease and finally no film could be deposited. These behaviors are discussed in relation with a role of GeF4 for the crystal growth at a low temperature.