Study On The Properties Of GaN-based HEMT

Gallium nitride(GaN) is a typicalthird-generationwide band gap semiconductormaterial,It has high thermal conductivity,highelectron driftvelocity,highbreakdown field strength, corrosion resistance,high temperature resistance,chemical stability, etc,which made it widely used in high-frequency, high-temperature and high-powermicrowave fields. AlGaN/GaN HEMT is the high electronmobility transistor,which is based on AlGaN/GaN heterostructuref and has high cutofffrequency,high saturation current,can adapt the power work environment.This paper mainly using SILVACO TCAD device simulationsoftware ATLAS to complete the computer simulat of AlGaN/GaN HEMT.Firstly, we set the device structural parameters ofAlGaN/GaN HEMT in DevEdit,Use TONYPLOT to output the device structure and dopingdistribution,get the electron density and the band situation in AlGaN/GaN heterojunction interface.The results show that using ATLAS to simulate the device structureand process parametersand is similar with the design;Secondly,analoging the current densities at AlGaN/GaN interface when the gate bias is zero and the drain voltage is0V,5V,10V,15V,20V,from this the generating process of the depletion region canbe clearly seen.The next is using ATLAS to simulate the transfer characteristics,transconductance,I-Vcharacteristics,C-Vcharacteristics of AlGaN/GaN HEMT,and compared with the experimental results, the results show that the simulation results are basically consistent with the experimental results,which validate the feasibility of ATLAS simulation.The study core of this work is build the device models of AlGaN/GaN HEMT,and change the relevant parameters(gate length,gate-drain spacing, etc.) tosimulate the performance of AlGaN/GaN HEMT using ATLAS.The results showed that reducing the gate length is advantage to increase the drain currentof the device,decrease the threshold voltage of the device,and to improve the transfer characteristics and I-Vcharacteristics of the device;Gate-drain spacing directly affects the equivalent resistance of the device,in the linear region,the larger gate-drain spacing threshold voltage and current of the saturated zone;Finally,simulating the suppress to current collapse of field plate structure, simulate the I-V characteristic curve of AlGaN/GaN HEMT with field plate or not,the results show that: with the increasing of the plate length,the peak electric field strength of the edge of the gate decrease.Field plate can increase the gate leakage current,so that increasing the reliability of AlGaN/GaN HEMT.