Heat Conduction Property Of Thin Films Tin Selenide

SnSe is a typical ?-? chalcogenide with a solid structure,low toxicity,low cost,and excellent thermoelectric properties.As thermoelectric materials,SnSe has attracted great attention.Keeping the electrical properties,the thermal conductivity decreases with the decrease of the dimension,result in improving thermoelectric properties.Moreover,size,defect,substrate,and ambient temperature also affect the thermal conductivity of materials.Therefore,it is significant to study the thermal conductivity of thin films single-crystalline SnSe.The Callaway model is modified by adding a scattering process to study the heat conduction properties of the thin single-crystalline SnSe layer.The results shows that SnSe is characterized with low thermal conductivity and anisotropy.And the thermal conductivity of SnSe depends on the phonon scattering process which is affected by ambient temperatures,thicknesses,and defect strengths.Then,the influence of the thermal conductivity by the size and substrate which cannot be reflected in the modified Callaway model is studied numerically based on the Flash method.The thermal conductivity increases with thickness,which is slightly lower than those calculated by the modified Callaway model,because thermal convection and thermal radiation were considered.Meanwhile,the thermal conductivity of supported SnSe depends on both substrates and its size.Finally,the two principal lattice axes of SnSe are determined using polarized Raman spectroscopy.The thermal conductivity of supported SnSe with thickness of 120 nm is studied by photothermal Raman method when laser polarization is along the different directions of SnSe crystal.The results shows that SnSe exhibit low thermal conductivity properties,and the heat conduction properties of SnSe has no significant effect with the incident direction of polarized light.