Photodoping of graphene/silicon van der Waals heterostructure observed by terahertz emission spectroscopy

Photodoping as a nonvolatile and reversible method can be used to modify the carrier distribution at the heterojunction interface. Herein, we explore the 2D/3D van der Waals (vdW) graphene/silicon (G/Si) heterostructure in real time by terahertz (THz) emission spectroscopy. Photoinduced doping is introduced by a continuous wave laser, which leads to a screening effect to the built-in electric field at the interface. The resulting decrease in transient photocurrent reduces the THz emission amplitude from the G/Si heterostructure. The photoinduced doping effect suggests a 40% THz intrinsic modulation depth at external reverse bias. This work provides an effective way to actively control the THz emission process from the G/Si interface and paves the way for analyzing the interfacial process under photoinduced doping in vdW heterostructures.