Cylindrical Field Effect Transistors Research Articles

Investigation of the Dyakonov-Shur instability for THz plasma waves in quantum gated cylindrical FET

Plasma waves may become unstable in the channel of field effect transistors (FETs) with asymmetric boundary conditions on source and drain, which is known as Dyakonov-Shur instability. In this letter, we extend the Dyakonov-Shur instability to the quantum gated cylindrical FET and obtain the dispersion equations describing unstable terahertz (THz) plasma waves using quantum cylindrical hydrodynamic equations. Research results show that the length of the channel and the wave vector of the circumferential direction inhibit the instability increment; however, the quantum effect, the radius of the channel, and the electron temperature enhance the instability increment. The oscillation frequency increases with the increase in the quantum effect, the wave vector of the circumferential direction, and the electron temperature, but the oscillation frequency increases with the decrease in the length and radius of the channel. Compared with the one-dimensional rectangular FET, THz plasma waves in the two-dimensional cylindrical FET have a higher oscillation frequency.

The instability of terahertz plasma waves in cylindrical FET

In this paper, the Dyakonov–Shur instability of terahertz (THz) plasma waves has been analyzed in gated cylindrical field effect transistor (FET). In the cylindrical FET, the hydrodynamic equations in cylindrical coordinates are used to describe the THz plasma wave in two-dimensional electronic gas. The research results show that the oscillation frequency of the THz plasma wave is increased by increasing the component of wave in the circumferential direction, but instability increment of the THz plasma wave are increased by increasing the radius of channel.