Breakdown of the semiclassical description of hot-electron dynamics inSiO2

Soft-x-ray photoemission measurements of the bulk Si 2p core level in Si/${\mathrm{SiO}}_2$ overlayer structures show that hot-electron transport in ${\mathrm{SiO}}_2$ is essentially independent of temperature between 300 and 980 K. These results reveal a basic failure of the semiclassical Monte Carlo formalism to correctly model the strong electron-phonon interaction in ${\mathrm{SiO}}_2$ at electron energies >6 eV. The experimental data are shown to be consistent with the trends seen in quantum Monte Carlo transport calculations.