Temperature dependence of Raman shifts in layered ReSe2 and SnSe2 semiconductor nanosheets

Abstract

Transition metal dichalcogenides (TMDCs) are attractive for variety of nanoscale electronics and optoelectronics devices due to their unique properties. Despite growing progress in the research field of TMDCs, many of their properties are still unknown. In this letter, we report measurements of Raman spectra of rhenium diselenide (ReSe2) and tin diselenide (SnSe2) layered semiconductor nanosheets as a function of temperature (70–400 K). We analyze the temperature dependence of the positions of eight ReSe2 modes and SnSe2 A1g mode. All observed Raman mode shifts exhibit nonlinear temperature dependence at low temperatures which is explained by optical phonon decay process into two or three acoustics phonons. The first order temperature coefficients (χ), determined for high temperatures, of rhenium diselenide Raman modes are in the range between −0.0033 and −0.0118 cm−1/K, whereas χ of tin diselenide A1g mode was −0.0129 cm−1/K. Our findings are useful for further analysis of phonon and thermal properties of these dichalcogenide layered semiconductors.

Ultrathin 2D GeSe2 Rhombic Flakes with High Anisotropy Realized by Van der Waals Epitaxy

“…The calculated χ coefficient is −0.00546 cm −1 K −1 for the peak at 210 cm −1 , which is several times smaller than those of other 2D layered materials such as SnSe 2 (A 1g mode, χ = −0.0129 cm −1 K −1 ), [35] MoS 2 (E 1 2g mode, χ = −0.0136 cm −1 K −1 ), [38] and SnSe (B 3g mode, χ = −0.03318 cm −1 K −1 ). The calculated χ coefficient is −0.00546 cm −1 K −1 for the peak at 210 cm −1 , which is several times smaller than those of other 2D layered materials such as SnSe 2 (A 1g mode, χ = −0.0129 cm −1 K −1 ), [35] MoS 2 (E 1 2g mode, χ = −0.0136 cm −1 K −1 ), [38] and SnSe (B 3g mode, χ = −0.03318 cm −1 K −1 ).…”

“…The EDX spectrum indicates an atomic ratio for Ge and Se of ≈1:2, in good agreement with the stoichiometry of GeSe 2 (Figure 2f). [19,35] Since all existing vibrational modes are A g modes, only the most intense peak at 210 cm −1 was studied in detail ( Figure 3a). Two peaks located at 32.3 and 55.1 eV can be assigned to the Ge 3d and Se 3d core-level peaks, respectively.…”

Temperature‐induced phonon behavior in titanium disulfide (TiS2) nanosheets

“…b and c show the detailed temperature dependence of the Lorentzian‐fit peak positions for the E g and A 1g phonons. The evolution of the E g and A 1g phonon wavenumbers ω (in cm ‐1 units) as a function of the temperature shows a linear behavior according to relation where ω 0 is the phonon wavenumber for temperature extrapolated to 0 K, χ is the first‐order temperature coefficient, and T is the absolute temperature . The linear dependence of phonon wavenumbers in TiS 2 thin layers are related to the anharmonicity of the interatomic potential, which results in phonon energy renormalization and thermal expansion, which can also modify the force constants.…”

Layer-dependent properties ofSnS2andSnSe2two-dimensional materials

“…8. Raman Shift (cm 19 . To our knowledge, there are no reports on single or few layer Raman spectra for SnSe 2 .…”

“…The unique electronic properties of single and few layer samples of these materials are being explored to develop novel applications in electronics 4 , photonics 5 , chemical sensing 6 , catalysis 7 and energy storage 8 to mention a few. Much of recent research activities in this field has been focused on transition metal chalcogenides such as MoS 2 9-11 , WS 2 9,12,13 , MoSe 2 14 , MoTe 2 15 and TaS 2 16 , while the interest in other 2D s-p metal chalcogenides has emerged only recently [17][18][19][20][21] . The discovery of the direct band gap in single layer of MoS 2 , which possesses the indirect band gap in the bulk 5 sparked the excitement of 2D research community, resulting in the observation of several unusual phenomena including very interesting exciton physics in these 2D materials [22][23][24][25] .…”