Rechargeable <i>E</i>′ centers in sputter-deposited silicon dioxide films

Abstract

An electron trapping instability in silicon dioxide films sputtered onto silicon substrates was analyzed by metal-oxide-semiconductor electrical methods and electron paramagnetic resonance (EPR), and was compared with an E′ defect model from molecular orbital cluster calculations. This comparison indicates that an E′ defect may well be responsible for the observed trapping instability, since electrically measured trap filling and emptying was quantitatively correlated with a reversible variation in the EPR signal magnitude. The specific model proposed for this defect is a ‘‘surface-like’’ or hemi-E′ center, O3≡Si−, which upon loss of an electron becomes O3≡Si+ and relaxes towards a planar configuration. The relaxation energy associated with the restoration of the original configuration is manifested as a hysteresis in the electrical trap filling and emptying cycle.