Abstract
This paper investigates the impact of lowK and high-K dielectric pockets on DC characteristics, analog/RF, and linearity performance of dual material stack gate oxide-tunnel field-effect transistor (DMSGODP-TFET). For this, a stack gate oxide with workfunction is considered to enhance the ON-state current (ION ), lower ambipolar current (Iamb) and lower the subthreshold swing. For this case, the gate electrode is tri-segmented, named as tunnel gate (M1), control gate (M2) and auxiliary gate (M3) with different gate lengths (L1, L2, L3) and work functions (φ1, φ2, φ3), respectively. To maintain dual-work functionality, the possible combinations of these work functions are considered. Technology computer-aided design (TCAD) simulations are performed and noted that the workfunction combination (φ1 = φ3 < φ2) outperforms as compared to other combinations. Where φ1 on the source side is used to enhance the ION , while φ3 (equal to φ1) is used on the drain side to minimize the Iamb. To further enhance the device performance, a high-K dielectric pocket is considered at the drain junction to suppress the Iamb whereas, a low-K dielectric pocket is employed at the source junction to enhance the ION . Moreover, length of gate segments, dielectric pocket height, and thickness are optimized to achieve a better switching ratio, subthreshold swing (SS) and reduce the Iamb which helps in the gain of device and design of analog/RF circuits. The proposed device as compared to dual material control gate-dielectric pocket-TFET (DMCG-DP-TFET) with SiO2 gate oxide shows improvement in ION /IOF F (∼ 4.23 times), 84 % increase in transconductance (gm), 136 % increase in cut-off frequency (fT ), 126 % increase in gain bandwidth product (GBP), point subthreshold swing (15.8 mV/decade) and other significant improvements in linearity figure of merits (FOMs) making the proposed device useful for low power switching, analog/RF and linearity applications.
Performance Assessment of Dual Material Stack Gate Oxide TFET using Dielectric Pocket