Nanoscale Thermal Behavior of 2D SnSe Nanosheets

The thickness-dependent nanoscale thermal behaviors of 2D SnSe nanosheets are studied via 3ω thermal mode atomic force microscopy and local Raman spectra. It is found that the 2D SnSe nanosheets demonstrate a decreasing thermal behavior with the reduction of thickness in the range of 6–40 nm. The unique thermal behavior is ascribed to the nonharmonic interlayer coupling along the armchair direction of SnSe crystal structure, in which the redshift of in-plane vibration (A2g, B3g) gives rise to phonon softening and finally the thickness-dependent thermal behavior of SnSe nanosheets. Such nanoscale thermal behavior provides a new insight to understand the local thermal transport of 2D materials and their applications in energy consumption.