New optimized Dual-Material (DM) gate design to improve the submicron GaN-MESFETs reliability in subthreshold regime

In this paper, new Dual-Material-gate (DM) concept and optimization approach are proposed to improve the device immunity against the hot carrier and short channel effects (SCEs), and optimize the subthreshold electrical performance of the submicron Gallium Nitride (GaN)-MESFET. The 2D analytical analysis includes the modeling of the channel potential, subthreshold swing, threshold voltage, Drain-Induced Lowering Barrier (DIBL) and parasitic resistances. The influence of gate length and the work function of each gate region on subthreshold behavior was investigated using the developed analytical models. The developed analytical approaches are verified and validated by the good agreement found with the 2D numerical simulations for wide range of device parameters and bias conditions. The presented compact models are used to formulate the different objective functions, which are the pre-requisite of multi-objective genetic algorithms optimization, which will be used to optimize the device subthreshold performances. The optimized design can alleviate the critical problem and further improve the immunity of SCEs of submicron GaN-MESFET-based digital circuits for low power and high speed applications.