Study On The Double-gate Tunneling Field-effect Transistor With InAs Source

Tunneling field effect transistor (TFET) is proposed as the potential candidate of conventional metal-oxide-semiconductor field effect transistor(MOSFET). The working mechanism of TFET is band-to-band tunneling mechanism, which is different from the drift-diffusion mechanism in MOSFET. From this point of view, this device has no exponential relationship between temperature and the current. Therefore, the sub-threshold current of TFET doesn’t limited by the thermal distribution of carriers and the SS of this device can successfully breaks the limitation of 60mV/dec that MOSFET suffers from. Also, off state current decreases, gate voltage become smaller and the static power consumption of this device reduces as well. However, TFETs suffer from a low drive current and ambipoar behavior due to short channel effect(SCE) and the AC behavior of TFET also need to be further investigated. To resolve these bottleneck issues, a new kind of double gate tunneling field effect transistors with InAs source(InAsDGTFET) is studied in detail. The contents mainly includes the direct current(DC) electrical characteristics, transient characteristics and stability of InAsDGTFET.In this paper, the structure of InAsDGTFET device has been established used the software TCAD-ATLAS firstly and based on the structure, DC electrical characteristics are simulated using this software. Also, the results have been compared with the conventional DGTFET. By optimizing the proposed device parameters, drive current can be achieved as high as 1.09×10-3A/μm, and ION/IOFF ratio is 1010 that far more than 106. Additionally, the sub-threshold swing(SS) of 30mV/decade is gained which breakthrough the limitation of 60mV/decade that MOSFET suffers. Also, variations in source, drain and channel doping concentrations, gate work function and silicon film thickness are investigated. It is found that drive current increases and the threshold voltage(Vth) as well as SS decreases when the doping concentration in source become larger. Doping concentration in drain mainly affects the bipolar effect of this device, and channel doping concentration in channel influence both drive current and off-state current due to channel is the bridge that connect source and drain. With the decreasing of gate work function, drive current becomes larger. However, considering that tunneling may have been occurs without voltage when the gate work function is lower than a value. Therefore, gate work function should not be reduced infinitely to pursuit larger drive current. At last, drive current continue decreasing with the increasing of bulk silicon.Secondly, AC characteristics is investigated. Based on a kind of n type non quasi static small signal equivalent circuit model, tunneling resistance(Rt) and channel resistance(Rc) are separated is this device. Also, the radio frequency(RF) performances of InAsDGTFET are studied and the discipline of parameters like Cgd、 Cgs、Cgg with the change of applied voltage have been discussed. Cut-off frequency(fT), maximum oscillation frequency(fmax) are extracted and analysed from the circuit model. By calculating the stability factor to study whether the device can keep stable unconditionally or not. Moreover, Y-parameters calculated from model and extracted from simulation show excellent agreement when the frequency up to about 300GHz. The results show that InAsDGTFET can be applied to the RF domain even in high frequency and it can keep stable under certain conditions.