AlN钝化层对AlGaN/GaN异质结及其高温特性的影响

Influences of AlN passivation dielectric on AlGaN/GaN heterostructure and its high-temperature properties

主要研究了AlN钝化介质层对AlGaN/GaN异质结势垒层应力的修改以及应力的变化对二维电子气高温输运性质的影响。研究结果表明:AlN介质层会对AlGaN势垒层产生附加的平面压应变;AlN和传统的Si3N4钝化介质都能减轻AlGaN势垒层在高温下的应变弛豫,但AlN介质层效果更明显。和传统的Si3N4钝化介质相比较,AlN钝化层不仅会显著增加AlGaN/GaN异质结二维电子气密度度,还会明显提高二维电子气迁移率,同时,AlN钝化后二维电子气密度的温度稳定性也更好。因此,对AlGaN/GaN异质结器件来说,AlN是一种有潜力的钝化介质。

The influences of AlN passivation dielectric on the strain change of the AlGaN barrier layer and the high- temperature transport properties of AlGaN/GaN heterostructure have been investigated in the present work. The results show that the AlN passivation layer will induce an additional biaxial compressive strain to AlGaN barrier layer. Both the AlN and traditional Si3 Nn passivation dielectrics can mitigate temperature - dependent strain relaxation of the AIGaN barrier, and AlN displayed a better effect. Compared to the traditional Si3 N4 dielectric, the AlN film led to an obvious increase not only in the concentration but also in the mobility of the two dimensional electron gas （2DEG） in AlGaN/GaN heterostrueture. Meanwhile, the variation of the 2DEG concentration with temperature in the AlN passivated sample is also smaller in comparison with that in the Si3N4 passivated sample. All these indicate that the AlN film is a promising passivation dielectric for AlGaN/GaN heterostructure devices.