Electronic states and modulation doping of hexagonal boron nitride trilayers

Abstract

We study the stabilities and geometric and electronic properties of hexagonal boron nitride $(h\text{\ensuremath{-}}\mathrm{BN})$ trilayers by using first-principles electronic-structure calculations within the framework of the density functional theory. From the results of total-energy calculations, we reveal the relative stabilities for various stacking sequences of $h$-BN trilayers. We also show that energy-band structures as well as spatial distributions of wave functions at the valence-band maximum (VBM) and the conduction-band minimum (CBM) strongly depend on the stacking sequences of the $h$-BN trilayers. We further investigate the effects of substitutional doping of a carbon atom on the electronic properties of the $h$-BN trilayers. In several stacking sequences of the C-doped $h$-BN trilayers, we find that the C-atom dopant can be spatially separated from the carrier transport layers associated with the VBM or the CBM, suggesting the possibility of realizing conduction channels only weakly disturbed by the C-atom impurity in $h$-BN trilayers. Interestingly, these donor states spatially separated from the CBM state are found to become rather shallow. This theoretical finding of ``atomically thin modulation doping'' using the $h$-BN layers may open an important way to design future layered electronic device materials.