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Actively controlling the performance of surface-enhanced Raman scattering (SERS) holds great promise in enabling novel applications of this technique. As a popular two-dimensional material, graphene shows intriguing tunable properties and thus has become a promising material in many potential active device applications. Here we proposed and experimentally demonstrated low-voltage electrically tunable SERS by using a plasmonic gold nanorod-graphene/ion-gel hybrid structure. The SERS signals of molecules adsorbed on such a structure were found to be continuously tunable through an external small bias voltage. As such a tuning process is highly related with the charge transfer between the adsorbed molecules and graphene, the proposed design is also helpful in understanding the charge transfer-based enhancement mechanism of SERS.

Hysteretic behavior in ion gel-graphene hybrid terahertz (THz) modulator is presented. The ion gel gated graphene modulator was designed and fabricated by conventional wet-based graphene transfer method. The modulation performance and hysteretic behavior of the device was characterized by THz time-domain spectroscopy. The dependence of hysteresis on the sweeping voltage rate and sweeping range was explored in a continuous wave terahertz system. The temporal response of the sample was also measured and fitted by a double-exponential expression, which indicated that there were two mechanisms that might cause the hysteresis in the THz modulator. This hysteretic behavior is promising in developing nonvolatile memory devices.