Temperature-dependent Raman spectroscopy analysis of single spiral WS2 nanosheets with screw dislocations

This study presents Raman spectroscopy measurements of Screw Dislocation Single Spiral Pattern SDD-SSP-WS2 samples supported on SiO2/Si at various locations, including the edge, middle, and center across temperatures spanning from 80 K to 560 K. A physical model that encompasses both the temperature effect and volume effect has been employed to comprehensively comprehend the nonlinearity temperature dependence of the A1gmode in a quantitative manner. It is shown that the four-phonon scattering and thermal expansion effect are the major causes of the Raman mode’s non-linear dependency. The thermal expansion effect and four phonons positively correlate with thicknesses , while the three-phonon scattering effect has an inverse relationship. The investigation of the full width at half maximum (FWHM) of the A1g mode has been conducted through experimental and theoretical means, utilizing various expressions within the identical temperature range. The observed broadening of FWHM A1g mode can be attributed to the decay of the A1gphonon. This study aims to enhance comprehension of the anharmonic characteristics and behaviors of phonons in SDD-SSP-WS2 flakes of varying thicknesses.