High-Mobility States and Dielectric Breakdown in Polymeric Dielectrics

We introduce a new experimental technique for directly measuring the energy and momentum scattering rates of hot electrons in dielectrics. Their energy distribution and impact ionization rate at a given electrical field F is a function of begin{equation*}F^{2} int^{E}_{0} gamma_{p}(E)gamma^{L0}_mu{ }(E)dEend{equation*} where ¿¿ is the momentum scattering rate and ¿Lo¿ the longitudinal optical phonon emission rate. Experiments on n-C36H74 show the energy loss rate to be governed by LO phonon emission (C-H stretch mode). Above E ~ 1.5 eV, ¿¿ is controlled by acoustic phonon scattering.