Jump to main content
Jump to site search

Issue 18, 2018
Previous Article Next Article

The phonon confinement effect in two-dimensional nanocrystals of black phosphorus with anisotropic phonon dispersions

Author affiliations

Abstract

The RWL model for the phonon confinement effect in nanocrystals (NCs) had been found to result in deviations and limitations for crystals exhibiting obvious anisotropic phonon dispersions and modified models have been proposed to overcome these deficiencies. Here, we examine this issue in black phosphorus (BP), a typical anisotropic two-dimensional crystal exhibiting pronounced anisotropy in phonon dispersions. A detailed study is performed on the Raman spectra of BP NCs prepared by the ion implantation technique. With decreasing NC size, the peak positions of the three characteristic Raman modes, Ag1, B2g and Ag2 modes, remain almost unchanged, while the Ag1 and Ag2 modes show significant asymmetrical broadening tails towards higher- and lower-frequency sides, respectively. It is found that the RWL model based on one-dimensional phonon dispersion along ΓY and ΓX axes in the Brillouin zone (BZ) cannot interpret the unusual frequency invariance and inhomogeneous line shape broadening of these three modes. However, after considering the contribution of two-dimensional anisotropic phonon dispersions from the whole BZ, the frequency and asymmetrical broadening of the Ag1 and Ag2 modes can be well reproduced. This study demonstrates that the RWL model can be applicable for crystals with anisotropic phonon dispersions once the phonons in the whole two-dimensional or three-dimensional BZ are properly taken into account, and provides a physically sound route into understanding the phonon confinement effect for anisotropic systems.

Graphical abstract: The phonon confinement effect in two-dimensional nanocrystals of black phosphorus with anisotropic phonon dispersions

Back to tab navigation

Supplementary files

Publication details

The article was received on 22 Feb 2018, accepted on 29 Mar 2018 and first published on 02 Apr 2018


Article type: Paper
DOI: 10.1039/C8NR01531G
Citation: Nanoscale, 2018,10, 8704-8711
  •   Request permissions

    The phonon confinement effect in two-dimensional nanocrystals of black phosphorus with anisotropic phonon dispersions

    T. Lin, X. Cong, M. Lin, X. Liu and P. Tan, Nanoscale, 2018, 10, 8704
    DOI: 10.1039/C8NR01531G

Search articles by author

Spotlight

Advertisements