Effect of substrate and growth parameters on the InAlN barrier layer in InAlN/AlN/GaN HEMT structure grown by MOVPE

In the GaN based high electron mobility transistor (HEMT), InAlN as a barrier layer offers superior device performance in terms of high frequency performance over the conventional AlGaN barrier layer. In this paper, the properties of InAlN/AlN/GaN HEMT structures grown by metal organic vapor phase epitaxy (MOVPE) employing InxAl1-xN as the barrier (0.13≤x≤0.17) is reported. After growth, these structures were characterized using high resolution X-ray diffraction (HRXRD), atomic force microscope (AFM) and Hall measurement. The results show that transport properties of two-dimensional electron gas (2DEG) depend on the composition of InxAl1-xN barrier layer. It was observed that, as the indium composition of barrier increases from x∼0.13 to x∼0.17, the sheet carrier density of 2DEG (Ns) decreases; where as there is a significant improvement in the mobility of 2DEG. Such a behavior of 2DEG properties may be attributed to the effect of strain state of barrier layer. For x