Impact of Interfacial Fixed Charges on the Electrical Characteristics of Pocket-Doped Double-Gate Tunnel FET

Tunnel FETs require the use of thin high- k dielectrics, which in turn necessitates the use of interfacial layer of SiO
₂
. The two oxide interfaces are seat of fixed charges, which directly affects the electrostatics within the device. In this paper, we use surface-potential-based analytical model to describe the effect of these charges on device electrostatics. Further, we compare the effects with a dimensionally similar MOSFET and demonstrate that tunnel FETs show relatively less variation with fixed charges and hence can replace MOSFETs in circuits where mechanisms such as NBTI/PBTI can degrade the output with continued usage. In order to show the effects of our findings at the circuit level, we design a tunnel-FET CMOS-based ring oscillator, where tunnel FET is used as a current source for CMOS-based oscillator core. Such a design not only decreases the effects of interface charges but also reduces the variations in frequency due to fluctuations in supply voltage.