利用金属有机化学气相沉积(MOCVD)设备, 在蓝宝石(0001)面上外延不同生长时间AlN隔离层的AlxGa1-xN/AlN/GaN结构的高电子迁移率的晶体管(HEMT), 研究了AlN隔离层厚度对HEMT材料电学性能的影响。研究发现采用脉冲法外延(PALE)技术生长AlN隔离层的时间为12 s(1 nm左右)时, HEMT材料的方块电阻最小,电子迁移率为1 500 cm2·V-1·s-1, 二维电子气(2DEG)浓度为1.16×1013 cm-2。AFM测试结果表明, 一定厚度范围内的AlN隔离层并不会对材料的表面形貌产生重大的影响。HRXRD测试结果表明, AlGaN/AlN/GaN具有好的异质结界面。

AlGaN/AlN/GaN HEMT structures were grown on sapphire substrate by MOCVD with different AlN growing time, and the influence of AlN thickness on electrical properties was investigated. When AlN growth time is about 12 s corresponding to the AlN thickness of 1～1.5 nm, the sample has the best performance of electrical properties with the lowest sheet resistance of 359 Ω·sq-1, the highest 2DEG concentration of 1.16×1013 cm-2, and a high 2DEG mobility of 1 500 cm2·V-1·s-1. AFM results indicate that AlN layer within a certain thickness range has little influence on the surface morphology. HRXRD results show that AlGaN/AlN/GaN HEMT has a good heterostructure interface.