High field current induced-positive charge transients in SiO2

Abstract

The formation of bulk positive charge in SiO2 induced by charge injection and high field conditions is studied in this work, utilizing new experimental methods. Using a dc hot electron injection technique it is shown that the presence of electrons in the SiO2 conduction band is a necessary condition for the positive charge formation. This result rules out field (only) induced mechanisms as possible explanations of high field positive charge generation in SiO2. The positive charge formation and annihilation are found to be governed by the same rate equation, and, therefore, exhibit similar behavior as a function of time. This behavior is consistent with an impact ionization-recombination model, with a recombination cross section σ=2×10−16 cm2 and ionization rate α which is in agreement with previous published values. However, other collision activated mechanisms cannot be ruled out.