Synthesis and Surface-Enhanced Raman Scattering of Ultrathin SnSe₂ Nanoflakes by Chemical Vapor Deposition.

As a new atomically layered, two-dimensional material, tin (IV) diselenide (SnSe₂) has attracted extensive attention due to its compelling application in electronics and optoelectronics. However, the great challenge of impurities and the preparation of high-quality ultrathin SnSe₂ nanoflakes has hindered far-reaching research and SnSe₂ practical applications so far. Therefore, a facile chemical vapor deposition (CVD) method is employed to synthesize large-scale ultrathin SnSe₂ flakes on mica substrates using SnSe and Se powder as precursors. The structural characteristics and crystalline quality of the product were investigated. Moreover, Raman characterizations indicate that the intensity of A peak and E peak, and the Raman shift of E are associated with the thickness of the SnSe₂ nanoflakes. The ultrathin SnSe₂ nanoflakes show a strong surface-enhanced Raman spectroscopy (SERS) activity for Rhodamine 6G (R6G) molecules. Theoretical explanations for the enhancement principle based on the chemical enhancement mechanism and charge transfer diagram between R6G and SnSe₂ are provided. The results demonstrate that the ultrathin SnSe₂ flakes are high-quality single crystal and can be exploited for microanalysis detection and optoelectronic application.