Low−temperature irradiation effects in SiO2−insulated MIS devices

Abstract

The storage of positive charge in the SiO2insulator of MIS devices has been studied at both 300 and 80 K. It has been found that additional charge is stored in the oxide as a result of low−temperature x irradiation and behaves differently from that induced by room−temperature irradiation. This additional charge may be removed from the oxide by photodepopulation techniques, field emission, and thermal annealing. The portion of the charge which is present at both 300 and 80 K is shown to be insensitve to these treatments under the same experimental conditions. The experimental data indicate that the observed behavior is not due to positive ion transport within the oxide and strongly suggests that hole transport is occurring. Models for the trapping sites and the role of surface states are discussed.