Influences of GeF4 on poly-SiGe films prepared by reactive thermal CVD

Abstract Polycrystalline silicon–germanium (Poly-SiGe) thin films are prepared by reactive thermal chemical vapor deposition (RTCVD) at substrate temperature of 450 °C using Si 2 H 6 and GeF 4 as source gases diluted in Helium. The influences of GeF 4 on the properties of poly-SiGe films have been investigated by varying the flow rates of GeF 4 . The results show that GeF 4 plays a very important role in poly-SiGe growth. Introduction of a small flow rate of GeF 4 can effectively promotes the nuclei formation on the substrate and decreases the incubation time. Ge content increases with GeF 4 flow rate and high Ge content results in an increase of the film surface roughness. It is also found that the film conductivity increases and activation energy decreases with the increase of Ge content.