不同插入层对抑制Mg掺杂p-GaN的记忆效应

研究了低温(LT) GaN和AlN不同插入层对抑制Mg掺杂p-GaN金属有机化学气相沉积外延中存在的记忆效应的影响,外延生长p-GaN缓冲层,制作具有该缓冲层的AlGaN/GaN高电子迁移率晶体管(HEMT),并对该器件进行电学测试.二次离子质谱仪测试表明p-GaN上10 nm厚的LT-GaN插入层相比于2 nm厚的AlN插入层能更好地抑制Mg扩散.霍尔测试表明,2 nm厚的AlN插入层的引入和GaN存在较大的晶格失配会引入位错,进而会降低AlGaN/GaNHEMT的电子迁移率以及增加其方块电阻;含有10 nm厚的LT-GaN插入层的p-GaN作为缓冲层的AlGaN/GaN HEMT,其方块电阻、电子迁移率以及二维电子气(2DEG)密度分别为334.9 Ω/口,1 923 cm2/(V·s)和9.68×1012 cm-2.器件具有很好的直流特性,其饱和电流为470 mA/mm,峰值跨导为57.7 mS/mm,电流开关比为3.13×109.

Memory Effect of Suppressing Mg Doped p-GaN by Different Interlayers

The memory effect of low temperature (LT) GaN and AlN interlayers on the Mg doped p-GaN grown by metal organic chemical vapor deposition was studied.The AlGaN/GaN high electron mobility transistors (HEMTs) with epitaxially grown p-GaN buffer layer were fabricated to carry out electrical testing.The secondary ion mass spectrometer test indicates that the LT-GaN interlayer with the thickness of 10 nm on the p-GaN can better suppress the Mg diffusion than the AlN interlayer with the thickness of 2 nm.The Hall test shows that the introduction of the AlN interlayer with the thickness of 2 nm and the large lattice mismatch of GaN may lead to dislocation,which may decrease the electron mobility and increase the square resistance of the AlGaN/GaN HEMT.The square resistance,electron mobility and two-demensional electron gas (2DEG) density of the AlGaN/GaN HEMT with the p-GaN buffer layer and the LT-GaN interlayer with the thickness of 10 nm are 334.9 Ω/□,1 923 cm2/(V · s) and 9.68× 1012 cm-2,respectively.The device has good DC characteristics and shows a high saturation current of 470 mA/mm,a peak transconductance of 57.7 mS/mm and the current on-off ratio of 3.13×109.