The optical signature of few-layer ReSe2

Abstract

Optical properties of thin layers of rhenium diselenide (ReSe 2 ) with thickness ranging from mono-(1 ML) to nona-layer (9 MLs) are demonstrated. The photoluminescence (PL) and Raman scattering were measured at low (T =5 K) and room (T =300 K) temperature, respectively. The PL spectra of ReSe 2 layers display two well-resolved emission lines, which blueshift by about 60 meV when the layer thickness decreases from 9 MLs to a bilayer. A rich structure of the observed low-energy Raman scattering modes can be explained within a linear chain model. The two phonon modes of intralayer vibrations, observed in Raman scattering spectra at about 120 cm −1 , exhibit very sensitive and opposite evolution as a function of layer thickness. It is shown that their energy difference can serve as a convenient and reliable tool to determine the thickness of ReSe 2 flakes in the few-layer limit.

Anisotropic Optical and Vibrational Properties of GeS

“…In terms of their crystal structures, these materials are characterized by a high in-plane symmetry. On the other hand, there is a group of materials with a low in-plane symmetry, which includes, e.g., black phosphorus (BP) [6][7][8], or Re-based dichalcogenides (ReS 2 and ReSe 2 [9,10]. Among these anisotropic materials, a new group of emerging vdW semiconductors, i.e., group-IV monochalcogenides MX (where M = Ge, Sn, or Pb and X = S, Se, or Te), has attracted increasing attention due to their anisotropic optical properties.…”

Beyond Graphene: Low-Symmetry and Anisotropic 2D Materials

“…Ł. Kipczak and collaborators studied the photoluminescence (PL) and Raman scattering properties of ultrathin ReSe 2 -whose thicknesses ranged from nine to one monolayer-at 5 K and at room temperature, 38 paving the way for the identification of few-layer ReSe 2 samples by optical means. The PL spectra of ReSe 2 layers display two well-resolved emission lines, which blue-shift by about 120 meV when the layer thickness decreases from nine monolayers to a monolayer, confirming a direct optical transition.…”

“…Their energy difference can serve as a convenient and reliable tool to determine the thickness of ReSe 2 flakes in the fewlayer limit. 38…”

The optical response of artificially twisted MoS$_2$ bilayers

“…Raman scattering (RS) and photoluminescence (PL) spectroscopies are extensively used experimental techniques to characterize layered materials. Particularly, they can be used to determine the thickness of each S-TMD thin layer due to the energy dependence of phonon vibrations [24][25][26][27][28][29][30][31] as well as to the direct-indirect band-gap transformation [1][2][3][4] .…”