Analog/RF Performance Estimation of a Dopingless Symmetric Tunnel Field Effect Transistor

An innovative dopingless symmetric tunnel field effect transistor (DLSTFET) has been investigated for its analog/RF performance. It tackles the unidirectional current limitation of conventional p–i–n TFET by allowing bidirectional flow of current due to band-to-band tunnelling through a germanium source/drain to channel through silicon pad layer. Detailed analysis has been carried out to investigate the impact of dielectric thickness and dielectric constant on device performance. DLSTFET with t_sox/t_dox= t_gox= 0.5 nm and HfO₂ as dielectric demonstrates optimum device performance with 86.7 µA/µm drive current, ~ 10⁶ I_ON/I_OFF and sub-threshold slope as 36 mV/decade. The benchmarking of a device with the state-of-the art TFET reveals that our reported TFET structure exhibits highest drive current. The reported structure has the inherent advantages of dopingless structure, such as easy fabrication, lower thermal budget, immunity towards the random dopant fluctuations and trap-assisted tunnelling effects. Thus, the structure subjugates the major issues of conventional TFET, i.e. low ON current and unidirectional current. Further, analog/RF performance parameters analysis depicts major improvement with reported cut-off frequency (f_T) as 26.7 GHz and gain-bandwidth product as 4.54 GHz. Hence, this device is best suited for low-power digital application as well as for analog applications.