Thin-film crystal growth of microcrystalline silicon using very-high-frequency hollow-electrode-enhanced glow plasma

The thin-film crystal growth of hydrogenated microcrystalline silicon (μc-Si:H) on SiO2 was investigated by using a very-high-frequency hollow-electrode-enhanced glow plasma system with an ultrahigh-vacuum reactor. The properties of the μc-Si:H thin films deposited with different flow rates of both mono-silane and hydrogen were characterized. We achieved fabrication of a μc-Si:H thin film with a growth rate of 4.0 nm/s, good photosensitivity, high crystallinity, and highly preferred crystal orientation along the < 110 > direction at a gas pressure of 80 Pa. To study the crystallographic structure in detail, cross-sectional transmission electron microscopy (TEM), limited-visual-field electron beam diffraction imaging, and high-resolution TEM were applied for the thin films deposited with the highest (4.0 nm/s) and lowest (0.25 nm/s) growth rates, respectively. The crystallographic images clearly show columnar growth of microcrystalline silicon in every region of the films, with a very thin transition layer less than 2 nm thick, suggesting direct growth from the substrate surface.