Unveiling anharmonic scattering in van der Waals semiconductor GaPS4 through Raman spectroscopy and theoretical calculation

The van der Waals thiophosphate GaPS₄ presents additional opportunities for gallium-based semiconductors, but limited research on phonon interactions has hindered optimization on thermal properties. This research undertakes a comprehensive investigation into the anharmonic phonon scattering within GaPS₄. The findings reveal pronounced anharmonic scattering, with both cubic and quartic phonon scatterings significantly influencing phonon redshift and broadening. Notably, the scattering strength is markedly higher in Raman peaks with higher wavenumbers, where quartic phonon scattering leads to conspicuous nonlinear broadening. Furthermore, a large amount of cubic and quartic scattering events is found to be Umklapp process. Besides, the molecular dynamics calculation quantitatively confirms the extensive redshift and broadening and suggests stronger anharmonic scattering beyond the Brillouin zone center. This research not only elucidates the anharmonic phonon scattering in GaPS4 but also provides theoretical foundation for further application. Concurrently, it enhances the understanding of anharmonic scattering in semiconductors within the condensed matter physics.