Temperature-dependent phonon dynamics of supported and suspended monolayer tungsten diselenide

Abstract

Two-dimensional materials exhibit great potential for high-performance electronics applications and the knowledge of their thermal properties is extremely necessary, since they are closely related to efficient heat dissipation and electron-phonon interactions. In this study we report the temperature-dependence of the out-of-plane A1g Raman mode of suspended and supported CVD-grown single-crystalline tungsten diselenide (WSe2) monolayer. The A1g phonon wavenumber is linearly red-shifted for temperature ranging from 98 to 513 K, with first-order temperature coefficients β of -0.0044 and -0.0064 cm−1/K for suspended and supported monolayer WSe2, respectively. The higher β module value for supported sample is attributed to the increase of the phonon anharmonicity due to the phonon scattering with the surface roughness of the substrate. Our analysis of the temperature-dependent phonon dynamics reveal the influence of the substrate on thermal properties of monolayer WSe2 and provide fundamental information for developing of atomically-thin 2D materials devices.

Low-Temperature Raman Investigations and Photoresponse of a Detector Based on High-Quality WSe2 Crystals

“…Temperature-dependent Raman spectroscopy can be employed to study the thermal conductivity, specific heat, and phase transitions . Being one the most important members of the TMDCs, temperature-dependent Raman spectroscopy is reported, but it is confined to single and bilayer ultrathin nanosheets. Herein, Raman spectroscopy is employed for multilayer crystals to expand the use of Raman spectroscopy as a nanometrology tool for single layer to multilayers .…”

Optical Switching Device Based on a Crystalline SnSe2 Photodetector in Diverse Conditions

“…The temperature dependence of the Raman shift is examined by linear fitting through expression ω = ω 0 + χT, where ω 0 and χ denote the frequency of the A 1g mode vibration at 0 K and first-order temperature coefficient, respectively. 37 The values of χ and ω 0 were found to be −0.0203 cm −1 K −1 and 188.29 cm −1 as investigated from the slope and intercept of the fitted straight line, respectively. Here, the negative sign of temperature coefficient reveals the inverse relation between temperature and Raman frequency that indicates shifting of Raman peak toward a higher frequency with a decrease in temperature.…”

Tungsten disulfide: synthesis and applications in electrochemical energy storage and conversion

“…Typically, high growth temperature leads to rapid surface diffusion and randomly deposited adatoms (these atoms tend to deposit at the energetically favorable sites), resulting in the three-dimensional (3D) island growth. On the other hand, low growth temperature gives rise to the amorphous or polycrystalline film, which is probably due to the reason that insufficient kinetic energy of adatoms to diffuse and find the lowest potential energy sites [74]. Atomic gas flux is another pivotal factor that is decisive to the growth quality of WS 2 film, and previous studies prove that sufficient high vapor pressure can guarantee the uniform mixing of atomic gases and is conductive to the movement of atomic species onto the substrate [75].…”