RingFET Architecture for High Frequency Applications: TCAD based Assessment

In this work, TCAD based investigation of RingFET architecture has been carried for high frequency applications. ATLAS TCAD device simulation software has been used to exploits the RingFET performance and are also compared with the equivalent bulk MOSFET. Parameters such as: cut-off frequency, max. transducer power gain, Stern Stability factor, Unilateral power gain, scattering parameters and parasitic capacitance (i.e. Cgs and Cgd)are evaluated. Maximum cut-off frequency of 3.7 THz has been achieved with RingFET (having drain outside)architecture at 32nm channel length. With the reduction in substrate doping, gate workfunction and enhancement in gate voltage, superior cut-off frequency can be achieved. Due to asymmetric nature of RingFET architecture, lower cut-off frequency is observed for drain inside case (i.e. 3.4 THz)compared to drain outside case of RingFET. Also, the change in gate to source capacitance Cgs with substrate doping is higher in comparison to gate to drain capacitance Cgd in RingFET.