One particular application of amorphous silicon oxide (SiO2), a material crucial for silicon device technology and design, is as a flash memory tunnel dielectric. The breakdown field of SiO2 exceeds 107 V cmÿ1. Strong electric fields in SiO2 give rise to phenomena that do not occur in crystalline semicon-ductors. In relatively weak electric fields (104ÿ106 Vcmÿ1), the electron distribution function is determined by the scattering of electrons on longitudinal optical phonons. In high fields (in excess of 106 V cmÿ1), the distribution function is determined by electron-acoustic phonon scattering.