基于p-SnO帽层栅的高阈值增强型AlGaN/GaNHEMTs

Wide-range-adjusted threshold voltages for E-mode AlGaN/GaN HEMT with a p-SnO cap gate

目前,p-GaN帽层技术是实现增强型GaN基HEMT的主流商用技术,但Mg掺杂难激活以及刻蚀损伤等因素限制了器件性能的进一步提升,因此高性能、低成本的增强型帽层技术具有重要的研究意义.本文采用p型氧化亚锡(p-SnO)代替p-GaN作为栅帽层引入AlGaN/GaN HEMT,并通过Silvaco器件仿真和实验验证两方面系统研究了器件的电学性能.仿真结果显示,通过简单改变p-SnO的厚度(50-200 nm)或掺杂浓度(3×10^(17)-3×10^(18)cm^(-3)),可以实现器件阈值电压在0-10 V范围内连续可调,同时器件的漏极电流密度超过120 mA mm^(-1),栅击穿和器件击穿电压分别达到7.5和2470 V.在此基础上,我们实验制备了基于磁控溅射p-SnO帽层的AlGaN/GaN HEMT,未经优化的器件测得了1 V的阈值电压、4.2 V的栅击穿电压和420 V的器件击穿电压,证实了p-SnO薄膜作为增强型GaN基HEMT栅帽层的应用潜力,为进一步提升增强型AlGaN/GaN HEMT性能,同时降低成本奠定了基础.

p-GaN cap layer has been recognized as a commercial technology to manufacture enhanced-mode(E-mode)AlGaN/GaN high electron mobility transistor(HEMT);however,the difficult activation of Mg doping and etching damage of p-GaN limit the further improvement of device performance.Thus,the more cost-effective cap layer has attracted wide attention in GaN-based HEMT.In this paper,p-type tin monoxide(p-SnO)was firstly investigated as a gate cap to realize E-mode AlGaN/GaN HEMT by both Silvaco simulation and experiment.Simulation results show that by simply adjusting the thickness(50 to 200 nm)or the doping concentration(3×10^(17)to 3×10^(18)cm^(-3))of p-SnO,the threshold voltage(V_(th))of HEMT can be continuously adjusted in the range from zero to 10 V.Simultaneously,the device demonstrated a drain current density above 120 mA mm^(-1),a gate breakdown voltage(V_(BG))of 7.5 V and a device breakdown voltage(V_(B))of 2470 V.What is more,the etching-free AlGaN/GaN HEMT with sputtered p-SnO gate cap were fabricated,and achieved a positive V_(th) of 1 V,V_(BG) of 4.2 V and V_(B) of 420 V,which confirms the application potential of the p-SnO film as a gate cap layer for E-mode GaN-based HEMT.This work is instructive to the design and manufacture of p-oxide gate cap E-mode AlGaN/GaN HEMT with low cost.