Structural Characterization of Ge Microcrystals in GexC1-x Films

Chemical and structural characteristics of Ge x C1-x films grown by metalorganic chemical vapour deposition are examined. The effects of the precursor nature (tetravinyl- or tetraethylgermane), growth temperature (in the 500-580°C range) and carrier gas (He or H2) are analysed using electron microprobe, X-ray diffraction, X-ray photoelectron, infrared and Raman spectroscopies. The film structure is governed by the growth conditions. It evolves between two border-line cases: An amorphous-like Ge phase embedded in a graphitic matrix and a polycrystalline Ge phase. A comparative study of the average grain size deduced from X-ray diffraction and Raman scattering data is presented.