Growth and Characterization of Germanium Carbon Thin Films Deposited by VHF Plasma CVD Technique

We report on the growth and characterization of germanium carbon alloy thin films. These films were deposited by very high frequency plasma chemical vapor deposition technique using monomethylgermane with hydrogen dilution. The carbon concentration of the films were varied 3 to 4 at. %. The film structure changed from amorphous to microcrystalline with increasing hydrogen dilution ratio. From Fourier Transform Infrared spectroscopy, we found that Ge-H bond and Ge-CH_n bond in the films were increased under low substrate temperature and low plasma power conditions. We obtained reduction of dark conductivity and increase of photosensitivity compare to the films deposited by HW-CVD