Growth of μc-SiGe:H thin films diluted with helium and hydrogen by VHF-PECVD

Inert gases, such as helium, argon and neon, have been successfully used to homogenize the plasma discharge in preparing a-SiGe alloys. In this work, varying proportional helium in hydrogen dilution is used to prepare μc-SiGe alloys by very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD) technology on a low-temperature substrate. The optical emission intensities of SiH* and Hα* in the plasma are in situ monitored, and Raman, photo-conductivity, and dark-conductivity of the alloys are measured. By contrast with alloys diluted with hydrogen only, we have found that metastable helium, which produces a plenty of atomic hydrogen, in favor of the growth of μc-SiGe alloys.