The Terahertz Radiation Characteristics Of Silicon Nano Devices

In this paper, the effects of lightly doped drain and source (LDDS) and hetero-material-gate(HMG) structure on the transport performance for MOSFET have been theoretically investigated bya quantum kinetic model. This model is based on two-dimensional non-equilibrium Green’sfunctions (NEGF) solved self-consistently with Poisson’s equation. Besides, we study the terahertzradiation and detection characteristics of nano field effect transistor, and obtain some significanceconclusions.The main works of this paper are as follows:Firstly, based on the non-equilibrium Green’s function (NEGF) and the self-consistent solutionof Poisson’s equation, we propose a dual-material-gate-MOSFET (DMG-MOSFET) quantummechanical model, which is established with finite element method (FEM). The transfer andsubthreshold and high frequency characteristics of DMG-MOSFET compared with single-material-gate MOSFET (SMG-MOSFET) are simulated. The results demonstrate that theDMG-MOSFET configuration exhibits a significant advantage in reducing SCEs and DIBL effects,as well as improving the performance of devices.Secondly, sets up the numerical simulation of THz radiation and detection based on thehydrodynamic equations, and use this model to study the THz radiation and detection characteristicsof DMG-MOSFET. The results show that, in the radiation mode, the change of the relaxation timewill influence the plasma wave in channel as well as the THz wave. While, in the detection mode,the change of ambient temperature, leakage current, plasma wave velocity, relaxation time and gatelength will affect the waveform of THz response.Thirdly, we propose a new LDDS carbon nanotube transistor with HMG structure(LDDS-HMG-CNTFET), and use a quantum kinetic model to study the electrical characteristics,subthreshold swing, scaling down and high frequency characteristics of it. Simulations show thatLDDS-HMG-CNTFET significantly decreases leakage current, subthreshold swing, and increaseson/off current ratio. In addition, effects of the gate electrode work function of theLDDS-HMG-CNTFET have been studied theoretically. The results indicate that, the electrontransport efficiency, and the cutoff frequency of the device, can be optimized by reasonablyselecting the gate electrode work function.