Devki N Talwar
Indiana University of Pennsylvania, USA
Title: Probing optical, phonon, thermal and defect properties of 3C-SiC/Si (001)
Biography
Biography: Devki N Talwar
Abstract
Comprehensive results of theoretical calculations are reported to probe the optical, phonon, thermal and defect properties of 3C-SiC/Si (001). By exploiting Raman scattering (RS) spectroscopy we have recently recognized amongst the conventional optical modes (~794 cm-1, 973 cm-1) in 3C-SiC, two extra phonons near ~ 625 cm-1 and 670 cm-1– possibly falling between the forbidden gap of the acoustic and optical branches. 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 in 3C-SiC has helped us evaluating the necessary force constant variations to construct perturbation matrices for intrinsic “complex-defect-centers”. For a nearest-neighbor “anti-site-pair” CSi–SiC defect, our methodical Greens function simulations of the gap modes have provided not only a strong support to the observed phonon features of DI-center but also afforded validation for a broad band observed near ~ 670 cm-1 in RS experiments.