高阈值电压低界面态增强型Al_2O_3/GaN MIS-HEMT

E-Mode Al_2O_3/GaN MIS-HEMT with High Threshold Voltage and Low-Interface-State

采用高温热氧化栅极凹槽刻蚀工艺并结合高温氮气氛围退火技术,制备出了高阈值电压的硅基GaN增强型Al_2O_3/GaN金属-绝缘体-半导体高电子迁移率晶体管(MIS-HEMT)。采用高温热氧化栅极凹槽刻蚀工艺刻蚀AlGaN层,并在AlGaN/GaN界面处自动终止刻蚀,可有效控制刻蚀的精度并降低栅槽表面的粗糙度。同时,利用高温氮气退火技术能够修复Al_2O_3/GaN界面的界面陷阱,并降低Al_2O_3栅介质体缺陷,因此能够减少Al_2O_3/GaN界面的界面态密度并提升栅极击穿电压。采用这两项技术制备的硅基GaN增强型Al_2O_3/GaN MIS-HEMT具有较低的栅槽表面平均粗糙度(0.24 nm)、较高的阈值电压(4.9 V)和栅极击穿电压(14.5 V)以及较低的界面态密度(8.49×10^(11) cm^(-2))。

GaN E-mode Al2O3/GaN metal-insulator-semiconductor high electron mobility transistors(MIS-HEMTs) with high threshold voltage were fabricated on Si substrate by using high-temperature thermal oxidation gate etching process and high-temperature nitrogen atmosphere annealing technique. The AlGaN layer was etched by using the high-temperature thermal oxidation gate etching process, which could be self-terminated at the AlGaN/GaN interface. And it could effectively control the etching accuracy and reduce the surface roughness. Simultaneously, the interface traps of the Al2O3/GaN interface were repaired by using high-temperature nitrogen annealing technology, and the body defects of Al2O3 gate dielectric were reduced. Therefore, the interface state density of the Al2O3/GaN interface was reduced and the gate breakdown voltage was increased. The GaN E-mode Al2O3/GaN MIS-HEMT fabricated on Si substrate by these two technologies has the advantages of lower surface average roughness(0.24 nm), higher threshold vol-tage(4.9 V),gate breakdown voltage(14.5 V) and lower interface state density(8.49×10^11 cm^-2).