Abstract
We present a Raman scattering study of optical phonons in hexagonal BN for temperatures ranging from 80 to 600 K. The experiments were performed on high-quality, single-crystalline hexagonal BN platelets. The observed temperature dependence of the frequencies and linewidths of both Raman active optical phonons is analyzed in the framework of anharmonic decay theory, and possible decay channels are discussed in the light of density-functional theory calculations. With increasing temperature, the mode displays strong anharmonic interactions, with a linewidth increase that indicates an important contribution of four-phonon processes and a marked frequency downshift that can be attributed to a substantial effect of the four-phonon scattering processes (quartic anharmonicity). In contrast, the mode displays a very narrow linewidth and weak anharmonic interactions, with a frequency downshift that is primarily accounted for by the thermal expansion of the interlayer spacing.
3 More- Received 19 July 2016
DOI:https://doi.org/10.1103/PhysRevB.94.155435
©2016 American Physical Society