The strong excitonic emission at 5.75 eV of hexagonal boron nitride (h-BN) makes this material one of the most promising candidate for light emitting devices in the far ultraviolet (UV). However, single excitons occur only in perfect monocrystals that are extremely hard to synthesize, while regular h-BN samples present a complex emission spectrum with several additional peaks. The microscopic origin of these additional emissions has not yet been understood. In this work we address this problem using an experimental and theoretical approach that combines nanometric resolved cathodoluminescence, high resolution transmission electron microscopy and state of the art theoretical spectroscopy methods. We demonstrate that emission spectra are strongly inhomogeneus within individual flakes and that additional excitons occur at structural deformations, such as faceted plane folds, that lead to local changes of the h-BN stacking order.
@article{arxiv.1401.1948,
title = {Excitons and stacking order in h-BN},
author = {Romain Bourrellier and Michele Amato and Luiz Henrique Galvão Tizei and Christine Giorgetti and Alexandre Gloter and Malcolm I. Heggie and Katia March and Odile Stéphan and Lucia Reining and Mathieu Kociak and Alberto Zobelli},
journal= {arXiv preprint arXiv:1401.1948},
year = {2014}
}