X-ray diffraction study of defect distribution in Czochralski grown silicon highly doped by As

A combination of x-ray diffraction methods and electron microscopy was used for the structural study of Czochralski silicon crystals highly doped by As. For as-grown crystals a weak strain field and probable clustering of As-impurity atoms follow from section topography and a reduction in the Borrmann effect intensity. For annealed crystals, it is shown that precipitates and dislocation loops are formed during annealing. The defects are located in highly distorted stripes lying nearly parallel to the crystal surface with period 200–300 µm. The concentration of the defects drastically decreases along the crystal radius from the centre to the periphery and along the growth axis from the seed. The average size of the defects obtained from the diffuse scattering increases with increasing distance from the centre to the periphery and along the growth axis from the seed. One concludes that the dependence of the defect parameters observed is associated with the change in oxygen concentration along the crystal radius and growth axis.