Study on Photoemission and Tunneling in Light - Modulated Scanning Tunneling Microscopy

We propose the utilization of a light-modulated scanning tunneling microscope (LM-STM) to study the plasmonenhanced photoemission and tunneling effect between metal tip and Au nanostructures on conductive substrate. The periodic Au nanorods are fabricated by electron beam lithography (EBL) and the topography is imaged using atom force microscopy (AFM) and STM. With irradiation of continuous lasers at 532 and 805 nm, the performance of electron tunneling emission is measured under STM's ramp mode. We show that, by exciting localized surface plasmon resonances (LSPRs), a tiny laser intensity of around 1 W/cm
²
along with a bias voltage less than 50 mV can activate a significantly enhanced tunneling current. This method has the potential for analyzing electron energy states and transport characteristics of surface plasmon.