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(1g) peak and E-g peak, and the Raman shift of E-g 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.