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Crystal Defects of Silicon Films Formed by Molecular Beam Epitaxy

Crystal defect properties of silicon films grown by molecular beam epitaxy are examined by Wright chemical etching and scanning electron microscope, and the following results are obtained. 1) The preheat treatment of substrates with oxides can drastically reduce the stacking fault and dislocation densities in Si films. The unevaporated SiO2 is a major source of these defects. 2) These defect densities decrease with an increase in deposition temperature. 3) The dependences of the defects on the residual gas pressure and the crystal faces of the substrates suggest that oxygen from the residual gas may form SiO2 which acts as the source of the defects in the films. 4) Ion doping during Si growth reduces the stacking fault densities in the films. 5) High quality Si epitaxial films whose defect densities are less than 103 cm-2 are obtained.