Probing optical, phonon, thermal and defect properties of 3C-SiC/Si (001)

Comprehensive results of experimental and theoretical studies are reported to probe the optical, phonon, thermal and defect properties of 3C-SiC/Si (001). By exploiting phonon-assisted Raman scattering (RS) spectroscopy we have recognized, among the conventional optical modes [To(Gamma) similar to 796 cm(-1) and LO(Gamma) similar to 973 cm(-1)], two extra phonon features near similar to 625 cm(-1) and 670 cm(-1) - possibly falling between the forbidden gap of the acoustic and optical branches. Temperature dependent profile of the unresolved similar to 670 cm(-1) band has indicated disordering by nearby defects and/or stress-rendering shorter phonon lifetime to instigate mode broadening. Accurate assessments of the lattice dynamical, thermal and defect properties are achieved by exploiting phonons from a rigid-ion model fitted to the inelastic x-ray scattering data and expending apposite group-theoretical selection rules. Lattice relaxations around Si/C atoms attained by the first-principles bond-orbital model for isolated defects have helped us to evaluate the necessary force constant variations for constructing perturbation matrices of the "complex-defect-centers". For isolated anti-site C-Si and Si-C defects (T-d-symmetry), our methodical Green's function (GF) theory has predicted triply degenerate F-2 gap modes near 630 cm(-1) and 660 cm(-1), respectively. The GF simulations of impurity vibrations for a neutral nearest-neighbor anti-site Si-C-C-Si pair-defect (C-3v-symmetry) provided gap-modes to appear within the broad similar to 670 cm(-1) band at 664.8 cm(-1) (a(1)) and 660.6 cm(-1) (e). The calculated results of localized vibrational modes are compared and discussed with phonon features observed in the RS experiments as well as with the density function theory. (C) 2014 Elsevier B.V. All rights reserved.