Novel digital terahertz device for three-state logic gate and phase coding based on graphene and Schottky barrier junctions

Terahertz technology, III-V group semiconductor devices, and graphene have great potential for broad applications in 6 G wireless communications. A novel digital terahertz device with nickel/GaN and graphene/GaN Schottky barrier junctions was proposed in this study. The patterned metal electrodes of the device, together with the graphene layer, formed a terahertz metasurface. The mechanisms of modulating the fermi level of graphene and the conductivity of the device to manipulate the transmission coefficient and reflected phase of terahertz waves were investigated using numerical calculations. The electrical and optical simulation results theoretically demonstrated that the three-state logic gate operation for the transmission coefficient of terahertz wave at 1.458 THz and the 1-bit reflected phase coding manipulation in 1.51-1.55 THz were realized. In addition, the maximum radar cross section reduction for the reflected wave was approximately 11.14 dB, comparing the designed coding sequences with the metal plate. These functions are mainly implemented by applying an external bias voltage to the device. This study provides a new and feasible strategy for designing digital terahertz manipulation devices.