First-Principles Study on Interlayer States at the 4H-SiC/SiO2 Interface and the Effect of Oxygen-Related Defects

摘要

We investigate the effect of SiC stacking and interfacial O defects on the electronic structure of the 4H-SiC/SiO2 interface via first-principles calculations. We find interlayer states along the SiC conduction band edge, whose location changes depending on which of two possible lattice sites, h or k, is at the interface. Excess O atoms at the interface lead to defect structures which alter the electronic structure. Changes to the valence band edge are the same whether h or k sites are at the interface. On the other hand, defects remove the interlayer state of the conduction band edge between the first and second SiC bilayers if an h site is at the interface, but have no effect when there is a k site. The variation of the conduction band edge at the interface is interpreted in terms of floating states, a particular property of SiC.