Bright Luminescence from Indirect and Strongly Bound Excitons in h-BN
At a Glance
Section titled āAt a Glanceā| Metadata | Details |
|---|---|
| Publication Date | 2019-02-12 |
| Journal | Physical Review Letters |
| Authors | Leonard SchuƩ, Lorenzo Sponza, Alexandre Plaud, H. Bensalah, Kenji Watanabe |
| Institutions | Office National dāĆtudes et de Recherches AĆ©rospatiales, Centre National de la Recherche Scientifique |
| Citations | 111 |
Abstract
Section titled āAbstractāA quantitative analysis of the excitonic luminescence efficiency in hexagonal boron nitride (h-BN) is carried out by cathodoluminescence in the ultraviolet range and compared with zinc oxide and diamond single crystals. A high quantum yield value of ā¼50% is found for h-BN at 10 K comparable to that of direct band-gap semiconductors. This bright luminescence at 215 nm remains stable up to room temperature, evidencing the strongly bound character of excitons in bulk h-BN. Ab initio calculations of the exciton dispersion confirm the indirect nature of the lowest-energy exciton whose binding energy is found equal to 300Ā±50 meV, in agreement with the thermal stability observed in luminescence. The direct exciton is found at a higher energy but very close to the indirect one, which solves the long debated Stokes shift in bulk h-BN.