Device Structure Design Of GaN Based HEMT Power Electronic Device

GaN based HEMT devices are one of the most concerned power electronic devices with very broad application prospects.To improve the working performance of HEMT devices in the field of power switching,it is necessary to optimize its structure and manufacturing process.It is important to improve the breakdown voltage,reduce gate leakage current,and increase the current density of the device.This article focuses on three aspects,which are improving the breakdown voltage of depletion-mode AlGaN HEMT devices,reducing the gate leakage of enhancement-mode GaN HEMT devices,and exploring high-current density ScAlN/GaN HEMT devices.The main research results of this paper are as follows:(1)Aiming to increase the breakdown voltage of HEMT devices,the Al_0.4Ga0.6N/Al_0.1Ga_0.9N HEMT devices with RESURF structure are proposed.By optimizing the doping density of the p-type doped region,the breakdown voltage is increased from 819 V to 1256 V when the doping density is 5×10¹⁸cm^-3.The threshold voltage of the RESURF structure AlGaN channel HEMT device is increasing from-2.71 V to-2.57 V compared with the conventional device.Then the electrical characteristics of the RESURF structure AlGaN channel HEMT device with the same doping concentration and different doping region lengths were studied.When the length of the doped region increases from 1?m to 4?m,the BV increases from 1256 V to 1746 V.Compared with conventional devices,its FOM has increased from 2.49×10⁸ to 8.28×10⁸ V²·?^-1·cm^-2.After introducing the p+doped region,a new electric field peak is introduced at the drain end of the doped region.For devices with different lengths of p+doed regions,the component integral area of the electric field distribution in the vertical direction is reduced,and the effect of optimizing the electric field distribution is finally achieved which improves the breakdown.Finally,the breakdown characteristics of RESURF Al GAN HEMT devices under different aluminum compositions are further discussed.For conventional AlGaN channel HEMT devices,when the Al composition of the channel/buffer layer increases from 10%to 25%,the breakdown voltage increases from 819 V to 1372 V,and the FOM increases from 2.49×10⁸ to 3.22×10⁸V²·?^-1·cm^-2.For RESURF structure AlGaN HEMT device,the breakdown voltage is increased from 1746 V to 2199 V as the Al composition of the channel/buffer layer increases from 10%to 25%.(2)The gate leakage of the GaN HEMT enhancement mode device with p-GaN cap layer is optimized by introducing the gate dielectric.First,treat the p-GaN of the GaN HEMT enhancement mode devices with O₂ plasma to study the influence of the O₂ plasma treatment on the threshold voltage and gate leakage.Research shows that the O₂ plasma treatment can reduce the gate leakage of the device effectively.When the gate voltage is 10V,the gate leakage of the device with 5 min,200 W O₂ plasma treatment is reduced near two orders of magnitude compared with the device without this treatment and the gate breakdown voltage is increased from 4.12 V to over 10 V.Besides,the introduction of Al₂O₃ gate dielectric into p-GaN enhancement HEMT devices could also reduce the gate leakage of the device,and the threshold voltage of the device is also increased from 2.27 V to 4.62 V.After combine the Al₂O₃ gate dielectric and gate-source bridge structure,threshold voltage can be increased from 2.27 V to 6.58 V.(3)The ScAlN/GaN HEMT devices with high current density are simulated.The device with V_TH=-14.89 V,switching ratio?10⁶,transconductance peak of 0.59 S/mm,and output current I_DS=4.77A/mm is obtained.The current density is much higher than that of conventional AlGaN/GaN HEMT devices.Subsequently,the p-GaN cap layer ScAlN/GaN high-current HEMT enhancement mode device is also simulated,with threshold voltage V_TH=1.98 V,switching ratio of?10⁶,transconductance peak value of 0.32 S/mm and the saturated output current I_sat is 1.91A/mm.The current density is much larger than the p-GaN AlGaN/GaN HEMT devices.When 20 nm Al₂O₃is introduced into the p-GaN ScAlN/GaN HEMT device,the threshold voltage of the device is increased to 4.83 V,and the threshold voltage can be reasonably modulated with the parameters of the gate dielectric.In summary,this article focuses on the design and optimize of breakdown voltage,p-GaN gate withstand voltage,and output current density of GaN-based HEMT devices.Satisfactory results have obtained by studying,demonstrating the huge advantages and broad application prospects of GaN-based HEMT devices in the field of power electronics.