Role of hydroxyl groups in the formation of defect configurations in silicon devices

Abstract

We use density functional theory to investigate five types of neutral hydroxyl group (-OH) defect within bulk Si, in terms of structural and electronic properties. We find that two out of these five defect configurations yield degenerate n-type direct current conductivity and intra-band gap levels that lie in the vicinities of both the valence and the conduction bands. For the other three defect configurations, the defect bands appear near the valence band maximum (VBM) only and the Fermi level lies close to the mid-gap. Our results are generally consistent with the available experimental data on hydrogen-, oxygen- and hydroxyl-related defect states in bulk Si. More importantly, a few new fairly shallow donor-like states are predicted by our simulations in the VBM vicinity. © 2008 IOP Publishing Ltd.