A first-principles study was made of all of the structurally different stacking faults that could be introduced by glide along the (00•1) basal plane in 3C-, 4H- and 6H-SiC. This was based upon the local-density approximation within density-functional theory. Band-structure calculations revealed that both types of stacking fault in 4H-SiC, and 2 of the 3 different types of stacking fault in 6H-SiC, gave rise to quasi 2-dimensional energy band states in the band-gap, at around 0.2eV below the lowest conduction band; thus being electrically active in n-type material. Although stacking faults, unlike point defects and surfaces, were not associated with broken or chemically perturbed bonds, a strong localization was found, within 1 to 1.5nm perpendicular to the stacking-fault plane, in the stacking fault gap-state wave functions. It was found that this quantum well-like feature of certain stacking faults in SiC could be understood in terms of the large conduction-band offsets between the cubic and hexagonal polytypes. Recent experimental results qualitatively supported these predictions.

Localized Electronic States around Stacking Faults in Silicon Carbide. H.Iwata, U.Lindefelt, S.Öberg, P.R.Briddon: Physical Review B, 2002, 65[3], 033203 (4pp)