Devki N Talwar
Indiana University of Pennsylvania, USA
Title: Spectroscopic phonon and extended x-ray absorption fine structure measurements on 3C-SiC/Si (001) epifilms
Biography
Biography: Devki N Talwar
Abstract
Comprehensive experimental and theoretical studies are reported to assess the vibrational and structural properties of 3C-SiC/Si (001) epilayers grown by chemical vapor deposition in a vertical reactor configuration. While the phonon features are evaluated using high resolution infrared reflectance (IRR) and Raman scattering spectroscopy (RSS)–the local inter-atomic structure is appraised by synchrotron radiation extended x-ray absorption fine structure (SR-EXAFS) method. Unlike others, our RSS results in the near backscattering geometry revealed markedly indistinctive longitudinal- and transverse-optical phonons in 3C-SiC epifilms of thickness d<0.4 μm. The estimated average value of biaxial stress was found to be an order of magnitude smaller while the strains were two-orders of magnitude lower than the lattice misfits between 3C-SiC and Si bulk crystals. Bruggeman’s effective medium theory was utilized to explain the observed atypical IRR spectra in 3C-SiC/Si (001) epifilms. High density intrinsic defects present in films and/or epilayer/substrate interface were likely to be responsible for (a) releasing misfit stress/strains, (b) triggering atypical features in IRR spectra and (c) affecting observed local structural traits in SR-EXAFS.