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 (TC) rapidly decreased with increasing Ge concentration (x). When x was small (=0–0.3), the highest crystallinity was ∼0.8 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 TC. 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.

The crystallization of SiGe-heterostructure in which a thin Ge layer put between Si layers has been investigated. When the Ge layer is inside the Si layer, the crystallization phenomena are similar to those of SiGe alloy layer; Ge completely diffuses in Si layer during the crystallization. When the Ge layer is at the interface between the Si layer and the quartz substrate, significant enhancement of crystallization has been found. In this structure, decrease in surface free-energy increases the nucleation rate at the interface and causes anomalous localization of Ge at the interface. When the Ge layer is on the surface of the Si layer, the crystallization property is quite different from the other structures. The underlying Si layer has large and aligned grains when the furnace annealing is assisted by the laser-annealing.A part of this work was carried out under the ASET program supported by NEDO, Japan.

Nucleation and growth properties of Si1-xGex (0≦x≦0.3) have been investigated by using ellipsometric spectroscopy. The incubation time and the crystallization time significantly decrease with increasing x; the estimated incubation time (and crystallization time) in Si0.7Ge0.3 is about 1/100 of that in Si. During the incubation time, the increase of the crystallinity has been observed which corresponds to the nucleation of crystal seeds. From the behavior of the crystallinity during the incubation and the crystallization time, we estimated the activation energy of the nucleation and the crystallization. Both energies monotonically decrease with increasing x. The saturated crystallinity after crystallization decreases with increasing x. It has been found that the effect of Ge reduces the crystallinity of Si1-xGex while significantly enhancing the crystallization.