Theoretical Predictions of Spectral Properties of Multilayer Boron Nitride Introduced by Point Defects

A theoretical study of several point defects of hexagonal boron nitride with a focus on their dependence on the layer structure has been performed. A doped layer and additional layers have been modelled by finite clusters stacked one over another. Computations have been performed with the tight binding model for geometry optimization and with the ZINDO method for simulating absorption spectra of all examined clusters, while time‐dependent density‐functional theory has been used for selected test cases. Studied defects include vacancies, single‐ and double‐atom substitutions, as well as combinations of these types, involving atoms such as Al, Si, C, H, while stacking types comprise AA′, AB, and AA bilayers, AA′A, ABC, ABA, and AAA trilayers, and additionally an AA′AA′A pentalayer. It has been found that additional layers may change significantly excitation energies and character of excited states, especially if the addition of a defect results in geometry changes, which disrupt the planarity of BN, like defects involving Si or nitrogen void with two hydrogen atoms.