Inhomogeneities in plastically deformed silicon single crystals. II. Deep-level transient spectroscopy investigations ofp- andn-doped silicon

The deep-level transient spectroscopy (DLTS) spectra of p- and n-type silicon samples, which were plastically deformed in the temperature range 390 °C≤${\mathit{T}}_{\mathit{d}}$≤800 °C with different resolved shear stresses 8≤τ≤200 MPa, can be quantitatively related to the deformation-induced ESR spectra. Deformation-induced point defects are inhomogeneously distributed and produce dominant energy levels in the lower half of the band gap. A smaller amount of dislocation-related defects causes energy levels in the upper part and in the middle of the band gap. The deformation-induced defects compensate p- and n-type material. The DLTS linewidths can be simulated by the introduction of a broadening parameter δ, which describes deformation-induced disorder. From its dependence on the applied deformation stress (21.5 meV/GPa in n-type material) and the similarity of the value to the pressure derivative of the conduction-band edge, we conclude that part of the disorder is related to fluctuations of the band edges. Contributions of fluctuating Coulomb potentials and variations of the capture cross sections caused by compensation probably contribute to the broadening of the energy levels. Similarities to polycrystalline materials are discussed.