Special features of the excitation spectra and kinetics of photoluminescence of the Si1 − x Ge x :Er/Si structures with relaxed heterolayers

Abstract

Luminescent properties of heteroepitaxial Si1 − xGex:Er/Si structures with relaxed heterolayers are studied. The results of combined studies of the excitation spectra and kinetics of photoluminescence (PL) are used to single out the components providing the largest contribution to the PL signal of the Si1 − xGex:Er/Si structures in the wavelength region of 1.54 μm. It is shown that relaxation of elastic stresses in the Si1 − xGex:Er heterolayer affects only slightly the kinetic characteristics of erbium luminescence and manifests itself in insignificant contribution of the defects and defect-impurity complexes to the luminescent response of the Si1 − xGex:Er/Si structures. In the excitation spectra of the erbium PL, special features related to the possibility of the rare-earth impurity excitation at energies lower than the band gap of the Si1 − xGex solid solution are revealed. It is shown that a peak the width of which depends on the band gap of the solid solution and the extent of its relaxation is observed in the excitation spectra of the erbium-related PL in the Si1 − xGex:Er/Si structures in the wavelength region of 1040–1050 nm. The observed specific features are accounted for by involvement of intermediate levels in the band gap of the Si1 − xGex:Er solid solution in the process of excitation of an Er3+ ion.