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The work deals with the implementation of charge plasma concept towards the formation of graded doping profile in the Drain region of Tunnel FET (TFET) device architecture. This new and innovative concept of graded doping profile in the lateral direction holds its merit towards stopping the ambipolar conduction in TFETs without affecting its off and the on state performance. The proposed device i.e. Undoped Drain Graded Doping based TFET (UDGD TFET) architecture is highly effective in suppressing the gate to drain and therefore the total gate capacitance values and thus also seems promising towards reduction in the dynamic power dissipation in TFETs. The architecture has also shown significant improvements for RF application in terms of cut-off frequency, Gain Bandwidth and Transit Time with optimized parameters such as gate work function, drain workfunction, channel length and drain region length when compared to conventional Tunnel FETs.

In this work, simulation-based research work based on a novel All-GaN-Integrated Cascode (AGC) MISHEMT with quaternary layer InyAlxGa1-x-yN as backbarrier has been investigated. The AGC-MISHEMT device consists of series combination of enhancement mode (recessed gate MISHEMT) and depletion-mode (MIS-gate) GaN devices with GaN/InAlGaN/GaN sandwich back barrier (SW-BB). TCAD simulations indicate that AGC-MISHEMTs with sandwich back barrier (SW-BB) exhibits simultaneous improvement in terms of drain current density (267 ​mA/mm), high ION/IOFFratio (108), transconductance-peak (191 ​mS/mm) and breakdown voltage (371 ​V) as compared to AGC-MISHEMT with GaN buffer. The impact of varying mole fractions (x, y), thickness and position of InyAlxGa1-x-yN layer on breakdown voltage has also been examined. Improvement in drain current density up to 40% has been accomplished with increased gate oxide thickness under gate 2 (depletion-mode device) for AGC-MISHEMT with SW-BB. Besides, power switching performance has been compared for AGC-MISHEMT with SW-BB to that of AGC-MISHEMT with GaN buffer and Recessed Single Gate (RSG) MISHEMT for inductive load circuit. Significant reduction in power switching losses (i.e. 43% during turn-ON time and 87% during turn-OFF time) has been observed for AGC-MISHEMT with SW-BB as compared to RSG-MISHEMT. In addition, introduction of quaternary InAlGaN layer in backbarrier for AGC-MISHEMT also results in considerable degradation (∼89%) in power loss when input gate is in OFF-state due to improved ION/IOFFratio in contrast with recessed single gate device.