[en] The signature of defects in the optical spectra of hexagonal boron nitride (BN) is investigated using many-body perturbation theory. A single BN-sheet serves as a model for different layered BN nanostructures and crystals. In the sheet we embed prototypical defects such as a substitutional impurity, isolated boron and nitrogen vacancies, and the divacancy. Transitions between the deep defect levels and extended states produce characteristic excitation bands that should be responsible for the emission band around 4 eV, observed in luminescence experiments. In addition, defect bound excitons occur that are consistently treated in our ab initio approach along with the "free" exciton. For defects in strong concentration, the coexistence of both bound and free excitons adds substructure to the main exciton peak and provides an explanation for the corresponding feature in cathodo- and photoluminescence spectra.
Disciplines :
Physics
Author, co-author :
Attaccalite, C.; Institut Neel, CNRS/UJF, Grenoble, France
Bockstedte, M.; Friedrich-Alexander-Universität Erlangen-Nürnberg - FAU
Marini, A.; Universidad del Paıs Vasco > Departamento Fısica de Materiales > Nano-Bio Spectroscopy Group and ETSF Scientific Development Centre
Rubio, A.; Universidad del Paıs Vasco > Departamento Fısica de Materiales > Nano-Bio Spectroscopy Group and ETSF Scientific Development Centre
Wirtz, Ludger ; Centre National de la Recherche Scientifique - CNRS > Department ISEN > Institute for Electronics, Microelectronics, and Nanotechnology (IEMN)
Language :
English
Title :
Coupling of excitons and defect states in boron-nitride nanostructures
Publication date :
2011
Journal title :
Physical Review. B, Condensed Matter and Materials Physics