Thermal effects on electron-phonon interaction in silicon nanostructures

TL;DR

This study investigates how thermal effects influence electron-phonon interactions in silicon nanostructures, using temperature-dependent Raman spectroscopy and theoretical modeling to distinguish thermal effects from quantum confinement and Fano effects.

Contribution

It provides a detailed analysis of thermal effects on Raman spectra in silicon nanostructures, incorporating temperature-dependent phonon dispersion in theoretical models.

Findings

Thermal effects dominate Raman spectra at temperatures above room temperature.

Experimental and theoretical Raman spectra show good agreement across temperatures.

Quantum confinement and Fano effects persist but are overshadowed by heating at higher temperatures.

Abstract

Raman spectra from silicon nanostructures, recorded using excitation laser power density of 1.0 kW/cm^2, is employed here to reveal the dominance of thermal effects at temperatures higher than the room temperature. Room temperature Raman spectrum shows only phonon confinement and Fano effects. Raman spectra recorded at higher temperatures show increase in FWHM and decrease in asymmetry ratio with respect to its room temperature counterpart. Experimental Raman scattering data are analyzed successfully using theoretical Raman line-shape generated by incorporating the temperature dependence of phonon dispersion relation. Experimental and theoretical temperature dependent Raman spectra are in good agreement. Although quantum confinement and Fano effects persists, heating effects start dominating at higher temperatures than room tempaerature.