Modulation doping of hexagonal boron nitride trilayers

We study stabilities and electronic properties of hexagonal boron nitride (h-BN) trilayers by using first-principles electronic-structure calculations within the framework of the density functional theory. It has been reported that there are five high-symmetry stacking sequences in the case of the bilayer h-BN, which shows various electronic properties depending on its stacking sequence. It is found that a wider variety of electronic structures can appear in the h-BN trilayer system. It is also found that spatial distributions of wave functions at the valence-band maximum and the conduction-band minimum strongly depend on the stacking sequence of the h-BN trilayer. We further study effects of substitutional doping of a carbon atom on electronic properties of h-BN trilayers. It is found that the layer with the dopant carbon atom can be spatially separated from the conducting layer(s) in several stacking sequences, indicating possibility of the modulation doping in as thin as the trilayer h-BN.