Luminescence of heteroepitaxial silicon films on sapphire

Low-temperature (4.2 K) photoluminescence of silicon on sapphire films with different thicknesses has been investigated. The experiments show that the common form of luminescence spectra in the energy range from 0.7 to 1.15 eV (the number of wide bands in the spectra, their shape, the energy position, the intensity) is strongly dependent oil the thickness pf the films. Some of these bands can be definitely assigned to radiative recombination at dislocations. It is found that in the luminescence spectra of silicon on sapphire films impurity-bound emission, bands are shifted relative to their position in single-crystal bulk silicon. The residual compressive stress in silicon on sapphire films is estimated, using the photoluminescence method.