Professor Emeritus Devki Talwar published “Anisotropic optical phonons in MOCVD grown Si-doped GaN/Sapphire epilayers” in the journal Materials Science & Engineering B.
Micro-Raman spectroscopy is employed to study the anisotropic optical phonons of Si-doped GaN/Sapphir epifilms grown by metal organic chemical vapor deposition method. In an undoped 3.6 μm thick sample—our polarized Raman measurements in the backscattering
geometry revealed major first order modes of GaN and sapphire. Careful analyses of the second-order Raman spectra using critical-point-phonons from a rigid-ionmode fitted inelastic X-ray spectroscopy data with appropriate selection rules helped us
attain expedient data for the lattice dynamics of GaN. In Si-doped films, a modified phonon confinement model is used for simulating Raman line shapes of Ehigh 2 phonons to monitor crystalline quality.
Department of Physics