Towards single-molecule detection: A novel hybrid system with two-dimensional GaTe sandwiched between Au nanoparticles and hole array

Abstract An ordered metal array normally can enhance the electric field near the surface by generating strong excitation of surface plasmons (SPs), while two-dimensional materials (2DMs) can ensure efficient adsorption of the aromatic molecules. Herein, an AuNPs/GaTe/Au-hole array structure for SERS is first theoretically simulated and successively prepared experimentally. The parameters of the Au-hole array are optimized through finite-difference time-domain (FDTD) numerical simulations; including period, depth, and geometry. With Rhodamine 6G (R6G) probe molecules, the strongest Raman signal is observed at the edge of the Au-hole. The corresponding enhancement factor reached as high as 1.8 × 106, which enabled the limiting detection concentration of 10−16 M of R6G, surpassing most of the existent SERS substrates. Simulations of GaTe, AuNPs/GaTe/Au-film, and AuNPs/GaTe/Au-hole array are applied to explain the observation of SERS activity in the Au-hole array structure. Moreover, the structure exhibited good reproducibility and stability.