Crystallization has been studied in amorphous germanium layers produced by evaporation. The crystalline fraction is deduced from conductivity measurements. Depending upon the conditions of evaporation homogeneous or heterogeneous nucleation is observed and the crystallization is induced at the surface or in the bulk. The variations with temperature of the growth rate of crystallization and of the nucleation rate are obtained from the kinetics of the crystallization measured at various temperatures. The results allow to provide orders of magnitude for the thermodynamical parameters which characterize the crystallization.

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Structure and crystal growth of undoped, as-deposited, and annealed silicon films prepared by chemical vapor deposition (CVD) and low-pressure chemical vapor deposition (LPCVD) of silane have been studied with use of x-ray diffraction, Raman spectroscopy, and scanning electron microscopy (SEM). The grain size and a complete texture analysis are performed on CVD films grown at atmospheric pressure and temperature range 600≤Td≤805 °C, LPCVD films grown in the pressure range 0.1≤Pd≤2 Torr and temperature range 500≤Td≤650 °C and annealed amorphous CVD and LPCVD films near Ta=600 °C. We obtain systematically amorphous, strong 〈220〉 polycrystalline, and inhomogeneous partially crystallized films 〈111〉 or 〈311〉 oriented depending on the deposition conditions. The presence of a given texture is explained by a model which takes into account the specific free surface energies of the starting equilibrium forms and the extinction of some crystalline planes by {111} slow growing facets. The appearance of the 〈220〉 texture is explained by a gas phase nucleation of crystal occurring during deposition, whereas the observed 〈311〉 texture of LPCVD films is supposed to be due to a gas-phase nucleation mechanism occurring during the first stages of deposition followed by a solid-phase crystallization mechanism.

Crystallization has been studied in amorphous silicon layers produced by evaporation. The crystalline fraction is deduced from conductivity measurements. Depending upon the conditions of evaporation homogeneous or heterogeneous nucleation is observed and the crystallization is induced at the surface or in the bulk. The variations with temperature of the growth rate of crystallization and of the nucleation rate are obtained from the kinetics of the crystallization measured at various temperatures. The results allow one to provide orders of magnitude for the thermodynamical parameters which characterize the crystallization.