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

• Optical, phonon, thermal and defect properties are reported for 3C-SiC/Si (001).
• Besides optical modes two weaker impurity modes are observed by Raman scattering.
• The broad band near 670 cm-1 lies close to the doublet seen in LT PL measurements.
• Realistic lattice dynamical calculations are performed to simulate phonon properties of both perfect and imperfect 3C-SiC.
• Gap-modes are calculated for isolated and nearest-neighbor anti-site pair defects.

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(Γ) ~ 796 cm− 1 and LO(Γ) ~ 973 cm− 1], two extra phonon features near ~ 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 ~ 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 CSi and SiC defects (Td-symmetry), our methodical Green's function (GF) theory has predicted triply degenerate F2 gap modes near 630 cm− 1 and 660 cm− 1, respectively. The GF simulations of impurity vibrations for a neutral nearest-neighbor anti-site SiC–CSi pair-defect (C3v-symmetry) provided gap-modes to appear within the broad ~ 670 cm− 1 band at 664.8 cm− 1 (a1) 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.