Gate-Voltage Tunability of Plasmons in Single-Layer Graphene Structures—Analytical Description, Impact of Interface States, and Concepts for Terahertz Devices

The strong light–matter interaction in graphene over a broad frequency range has opened up a plethora of photonics applications of graphene. The goal of this paper is to present the voltage tunability of plasma waves in gated single-layer graphene structures and to quantify their distinction from the plasma waves in ungated graphene structures. Device concepts for plasmonic interconnects and antennas and their performance for THz communication are presented. For the first time, the role of gate voltage and the thickness of the gate dielectric on the characteristics of plasmon propagation in graphene are quantified by accounting for both the interface trap capacitance (substrate dangling bonds and gate-insulator traps) and the quantum capacitance. The gate voltage serves as a powerful knob to tweak the carrier concentration and allows building electrically reconfigurable terahertz devices. By optimizing the gate voltage to maximize the plasmon propagation length in gated graphene structures, we derive simple scaling trends that give intuitive insight into device modeling and design.