Investigation of Raman enhancement in hydrothermally roughened SERS-active substrates

In this work, we study surface enhanced Raman spectroscopy (SERS) active substrates for the detection of Rhodamine 6G. To examine the electromagnetic enhancement, we apply the finite-difference time-domain (FDTD) algorithm to analyze the structures by solving a set of coupled Maxwell's equations (Ampere's Law and Faraday's Law) in differential form. The field enhancements are thus investigated in the visible regime with the wavelength of 633 nm. In our experimental measurement, the surface enhanced Raman scattering signals from the surface of substrates with 12-hour treatment and without treatment are performed and compared. Through the three-dimensional (3D) FDTD calculation, we find that the hydrothermally 12-hour treated samples possess significantly vertical variations of surface and thus have relatively larger field enhancement than those without treated. Consequently, it implies a strong positive effect on the surface enhancement which is consistent with the measured intensity.