Electron-Phonon and Phonon-Phonon Interactions Under Laser Annealing Conditions

Abstract

ABSTRACTSince the first time-resolved Raman studies of pulsed laser annealing (PLA) effects in Si, a number of cw Raman studies have been performed which provide a much improved basis for understanding the consequences on Raman spectra of temperature-dependent resonance effects, high carrier density effects, phonon anharmonicity, and strain effects. Here we briefly review these effects and then analyze the latest pulsed Raman studies of PLA including Stokes/anti-Stokes ratios, the shift and shape of the first order line, and time-resolved second-order spectra. The Raman data indicate the existence of a Raman-silent phase followed by a rapidly cooling solid which begins within 300 K of the normal melting temperature of Si. The Raman data also give evidence of carrier densities in the recrystallizing solid of ~1−2×l019/cm3 .