THz emission in nano-graphene field-effect transistors with non-ideal boundary condition

Plasma wave instability in field-effect transistors constitutes a viable mechanism for generating terahertz (THz) electromagnetic radiation. This study investigates the instability characteristics of THz plasma waves in graphene field-effect transistors (GFETs) under non-ideal boundary conditions, employing a self-consistent quantum hydrodynamic model that incorporates viscosity and collision effects. Through numerical simulations, we systematically analyze how a weak magnetic field, quantum effects, viscosity, and collisions influence the plasma wave instability. Our results demonstrate that increasing the viscosity coefficient or the collision term suppresses the THz radiation frequency. Furthermore, enhancements in magnetic field intensity, transverse wave vector, viscosity, or collision term concurrently reduce both the plasma wave oscillation frequency and its instability gain. This study confirms that the THz performance of GFETs can be effectively tuned via device scaling, capacitance ratios, and magnetic bias. These adjustable parameters provide critical theoretical insights for optimizing the trade-off between radiation efficiency and operational stability, paving the way for the tailored design of advanced THz functional devices.