Electron self-trapping in SiO2

Abstract

Electron trapping and detrapping behavior of SiO₂ has been studied at different temperatures by applying avalanche injection technique to metal oxide semiconductor capacitors. Experimental evidence is presented for the transfer of electrons initially captured at 100 K by shallow centers with σ≂10⁻¹⁶ cm² to the deep centers with σ≂10⁻¹⁹ cm². The trapping sites with σ−¹⁶ cm² that are located near Si‐SiO₂ interface exhibit the highest probability of charge transfer. The centers with σ>10⁻¹⁶ cm² show no transfer of charge. It is proposed that the electrons localized at 100 K by the centers with σ≤10⁻¹⁶ cm² undergo a self‐trapping process that is triggered by a lattice relaxation. The lattice relaxation seems to be encouraged by the strain in the interfacial region.