Effects of tin doping on crystallization of amorphous silicon were studied using Raman scattering, Auger spectroscopy, scanning electron microscopy, and X-ray fluorescence techniques. Formation of silicon nanocrystals (2–4 nm in size) in the amorphous matrix of Si1−xSnx, obtained by physical vapor deposition of the components in vacuum, was observed at temperatures around 300 °C. The aggregate volume of nanocrystals in the deposited film of Si1−xSnx exceeded 60% of the total film volume and correlated well with the tin content. Formation of structures with ∼80% partial volume of the nanocrystalline phase was also demonstrated. Tin-induced crystallization of amorphous silicon occurred only around the clusters of metallic tin, which suggested the crystallization mechanism involving an interfacial molten Si:Sn layer.

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Microstructure investigations of thin Si-Sn alloy films were carried out, by using Auger and Raman spectroscopies, X-ray fluorescence analysis, and electron microscopy. The films were produced by the thermal-vacuum coevaporation of Si and Sn. The properties of films with the Sn content ranging from 1 to 5 wt.% are studied. A significant influence of the tin impurity on the formation of a film surface microrelief and nanocrystals in the amorphous matrix is found. The size of quasispherical formations on the film surface can be of the order of 100 nm. The volume fraction of the silicon nanocrystalline phase in a film can reach 90%. The roles of fabrication conditions and growth rate on the distributions of Sn and technological impurities C and O over the film surface and across the film thickness are analyzed. K e y w o r d s: Microstructure of thin composite films, Auger method, Raman spectroscopy.

Influence of isochronal annealing in the range of 350-1100 • C on the structural properties and the intrinsic absorption edge in thin silicon films doped with tin (a-SiSn) has been studied. It is found that as-deposited a-SiSn films with a tin content of about 4 at.%, unlike undoped a-Si ones, contain silicon nanocrystals with a crystallite size of about 4 nm and a crystalline fraction of about 65%. It is shown that, in the course of isochronal annealing of a-SiSn specimens in the interval of 350-1100 • C, the size of silicon nanocrystals in the amorphous matrix gradually increases to about 7 nm, and the fraction of crystalline phase to about 100%. Crystallization in undoped a-Si is observed only after the annealing at temperatures above 700 • C. The influence of tin on the optical band gap in a-Si as a function of the isochronal annealing temperature is analyzed.K e y w o r d s: thin-film silicon, doping with tin, crystallization, optical band gap, isochronal annealing.