Electron trapping in thin films of thermal SiO2 at temperatures between 30 and 300 K

Abstract

Temperature dependence of electron trapping in thermally grown SiO2 has been studied using metal–silicon dioxide–silicon (MOS) structures. The MOS samples are charged using avalanche injection from the Si substrate at temperatures between 30 and 300 K. It is found that the rate of electron trapping increases monotonically as temperature decreases from 300 to 30 K for both oxides subjected to H2/N2 annealing and oxides subjected to no H2/N2 annealing. The majority of electrons trapped at 77 K is thermally reemitted, as the samples are warmed to room temperature. Analyses of the experimental results indicate that neutral trap centers responsible for electron trapping are characterized by the two discrete energies of 23 and 4 meV below the conduction band edge of SiO2.