Intricate Resonant Raman Response in Anisotropic ReS2

Published

August 18, 2017

Author(s)

Amber McCreary, Jeffrey R. Simpson, Yuanxi Wang, Daniel Rhodes, Kazunori Fujisawa, Luis Balicas, Madan Dubey, Vincent H. Crespi, M. Terrones, Angela R. Hight Walker

Abstract

Rhenium disulfide is an exciting material due to its strong in-plane anisotropy, thus offering an additional physical parameter that can be tuned for advanced applications. ReS2 provides a major advantage for optoelectronics as it is both stable in air and has been shown to be a direct-gap semiconductor for few-layers and bulk thicknesses, unlike MoS2 or WS2. Raman spectroscopy is one of the most powerful characterization techniques to non-destructively and sensitively probe a plethora of fundamental photo-physics in a material. Here, we perform a thorough study of the resonant Raman response of the 18 first-order phonons in ReS2 at various layer thicknesses and crystal orientations. Remarkably, we discover that, as opposed to a general increase in intensity of all of the Raman modes at a resonance condition, each of the 18 modes behave differently relative to each other as a function of laser excitation, layer thickness, and orientation in a manner that suggests the importance of electron-phonon coupling in ReS2. In addition, we correct an unrecognized error in the calculation of the optical interference enhancement of the Raman signal of transition metal dichalcogenides on SiO2/Si substrates that has been propagated through various reports. For ReS2, this correction is critical to properly identifying the resonant Raman behavior of the modes. We also implemented a perturbational approach to calculate frequency-dependent Raman intensities from first- principles and demonstrate that, despite the neglect of excitonic effects, useful trends in the Raman intensities of monolayer and bulk ReS2 at different laser energies can be accurately captured. Finally, phonon dispersions calculated from first-principles and scanning transmission electron microscopy were used to address possible origins of unexplained peaks observed in the Raman spectra, such as infrared-active modes, defects, and second-order processes.

Citation

Nano Letters

Volume

17

Issue

10

Pub Type

Journals

Download Paper

https://doi.org/10.1021/acs.nanolett.7b01463

Local Download

Keywords

Rhenium disulfide, ReS2, polarization, Raman, laser wavelength, Resonant Raman, anisotropy, defects

Citation

McCreary, A. , Simpson, J. , Wang, Y. , Rhodes, D. , Fujisawa, K. , Balicas, L. , Dubey, M. , Crespi, V. , Terrones, M. and Hight Walker, A. (2017), Intricate Resonant Raman Response in Anisotropic ReS2, Nano Letters, [online], https://doi.org/10.1021/acs.nanolett.7b01463, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=923026 (Accessed March 13, 2025)