Light-driven ultrafast electric gating

Abstract

A source and drain electrode are spaced apart by an optically exposed gate region above a surface photovoltage effect (SPV) bulk. A two-dimensional material is deposited upon the gate region. The gate region is activated by exposure to an ultrafast light pulse, which may be infrared or near-infrared, and may be a focused collimated laser pulse with a sub-picosecond width. The pulse causes electron-hole pair generation resulting in band bending in the SPV material, which generates an electric field within the 2D material, thereby modifying the electronic properties between source and drain via a field-effect. After passage of the pulse, conduction continues in the device until the conductive electron-hole pairs recombine during the SPV decay time. The two-dimensional material may comprise a crystalline atomic monolayer. The activation is repeatable with subsequent pulses, resulting in the device cycling on and off within timescales less than 200 picoseconds.