Characterization of plasma-deposited microcrystalline silicon

Microcrystalline silicon composed of crystalline and amorphous phases has been prepared by the glow discharge of a SiH4 + H2 gas mixture. The volume fraction of the crystallites and dark conductivity are simultaneously increased either by increasing the r.f. power or by decreasing the silane concentration. As the proportional content of the microcrystallites increases, only the number of crystallites is increased without any appreciable accompanying change in the grain size. On the basis of the structural model of microcrystalline silicon, it is suggested that the current transport of well-crystallized film is dominated by conduction in the crystallites. A nucleation mechanism of microcrystallization is discussed in conjunction with in-situ optical emission spectroscopy of the silane plasma.