Dyakonov-Shur Instability in cylindrical Terahertz Field Effect Transistor with nonideal boundary condition

Abatract Terahertz (THz) plasma waves in field-effect transistors (FETs) have garnered significant attention in recent years due to their potential applications. This study investigates the instability of terahertz (THz) plasma waves in cylindrical FETs under nonideal boundary conditions. The dispersion relation describing the instability of THz plasma waves is obtained using a linearization method and quantum fluid dynamics equations governing the collective behavior of two-dimension electron gas in the cylindrical FETs’ channel. By combining the dispersion relation with the boundary conditions, the instability increment and the radiation frequency are investigated numerically. The numerical results indicate that under non-ideal boundary conditions, the plasma waves become unstable when the source capacitance exceeds the drain capacitance. Furthermore, the oscillation frequency of the plasma waves can be increased by either raising the electron temperature or increasing the mode number. This study provides valuable insights into the dynamics of plasma waves in cylindrical FETs, guiding future research and development efforts aimed at improving the performance and reliability of THz devices.