Growth and characterization of microcrystalline silicon–germanium films

Microcrystalline (μc) thin films of Si1−xGex:H (0.16⩽x⩽0.89) were prepared on quartz, Cr-evaporated Si(1 0 0) and H-terminated Si(1 0 0) by plasma-enhanced chemical vapor deposition (CVD) from SiH4+GeH4+H2 gas mixtures with various GeH4/SiH4 molar fractions and substrate temperatures. The crystallinity of the films was characterized by Raman scattering spectroscopy and transmission electron microscopy (TEM). We have demonstrated the formation of a highly crystallized and structurally relaxed Si1−xGex network with nearly homogeneous composition in the temperature range 200–300 °C. However, for the deposition on quartz and Cr-evaporated Si(1 0 0), the crystallite nuclei emerge after the growth of the amorphous layer as thick as 25 nm which is markedly larger than the incubation layer thickness for μc-Si:H (typically ∼5 nm under a similar deposition condition).