Solid-phase crystallization of Si1-xGex alloy layers

Solid-phase crystallization of Si1-xGex (x = 0-1.0) alloy layers deposited on a Si (100) substrate was investigated by ellipsometric spectroscopy. From a dispersion analysis of dielectric spectra, we deduced a crystallinity corresponding to the degree of average lattice alignment of the composed polycrystalline Si1-xGex layers and investigated the dynamical change in crystallinity during crystallization. We found that the crystallinity and crystallization temperature (T-C) rapidly decreased with increasing Ge concentration (x). When x was small (=0-0.3), the highest crystallinity was similar to0.8 of that for single crystals while the lowest one was considerably below 0.6 when x > 0.8. Moreover, the crystallinity decreased with increasing temperature above T-C. We investigated the nucleation rate during crystallization and found that the decrease in crystallinity at both large Ge concentration and high temperature can be explained by a trade-off between the nucleation and crystallization rates; nucleation was dominant under these conditions. An overview of the crystallinity of solid-phase crystallized Si1-xGex alloy layers is provided. (C) 2001 American Institute of Physics.