Temperature dependence of the current in SiO₂ in the high field tunneling regime

Abstract

In this work, we study the effect of temperature on the tunneling current in thin SiO2 films (≊200 Å) and show that a reversal of behavior is produced by increasing fields. While in the lower range (≤9 MV/cm) the current is well represented by the Fowler-Nordheim model and increases with temperature, it substantially disagrees with the theory at fields close to breakdown (>10 MV/cm) where it is larger than expected and decreases with increasing temperature. This cannot be explained with the formation of (quasi) stable positive charge which is known to be created by high field stress but, under our experimental conditions, is found to be negligibly small. Therefore, we deal with a new kind of effect for which few different possibilities are suggested as mechanisms at the microscopic level.