A Study On New Structures Of GaN-on-Si Power MISFET

The third generation semiconductor Gallium Nitride(GaN)attracts extreme attention in the field of high frequency and high power application for the high mobility 2DEG formed in the heterojunction via GaN and its multi-alloy like AlGaN with wide band-gap.In order to be compatible with traditional Silicon process platform and shrink the cost,GaN-on-Si enhanced AlGaN/GaN power MISFET technology is the key in the research nowadays.However,conventional Al GaN/GaN enhancement-mode device relies on the dry-etch process desperately,which features low precision in device forming.This thesis is trying to solve these problems through the research on novel structures design from the perspective of structure-model-simulation.The foci of this thesis are as follows:(1)The analysis and discus on the fabrication process of conventional enhanced AlGaN/GaN power MISFET,for instance recessed gate,p-cap layer,Fluoride plasma treatment and so on.And the solution scheme of the defects of the technologies aforementioned like unstable threshold voltage in recessed gate devices,harsh activate process in p-type GaN and blunt subthreshold swing,namely a novel gate-modulated matel-2DEG tunneling FET(TFET)is investigated.(2)In order to avoid the defects of conventional heterojunction device and solve the problems introduced by the TFET,SG-TFET is presented.Based on SG-FET,the shallow field plate integrated with gate technology(SFG)and a novel FET that is so called SFG-FET are proposed with a high temperature repid dry-etching process recipe.In the mean time,a MISFET-style Gama-shaped anode SBD with SFG(GA-SBD)is presented to realize ultro-low turn-on voltage and high blocking capability.After that,some voltage-current models are established by mathematical physics method,and,prove that these new structures with slope subthreshold swing,strong capability of power transportation and functional integration,enable the fault tolerance of etch technology more or less.