Improved mobility in InAlN/AlGaN two-dimensional electron gas heterostructures with an atomically smooth heterointerface

Abstract

We attempted to improve the mobility of InAlN/AlGaN two-dimensional electron gas (2DEG) heterostructures by achieving an atomically smooth heterointerface in metalorganic chemical vapor deposition processes. In the result, it was confirmed that the high-growth-rate AlGaN layer was very effective to improve the surface morphology. The atomically smooth surface morphology with a root-mean-square roughness of 0.26 nm was achieved for an Al0.15Ga0.85N layer under the growth rate of approximately 6 µm/h. Furthermore, nearly lattice-matched In0.17Al0.83N/Al0.15Ga0.85N 2DEG heterostructures with the atomically smooth heterointerface exhibited a 2DEG mobility of 242 cm2 V−1 s−1 with a 2DEG density of 2.6 × 1013/cm2, which was approximately 1.5 times larger than the mobility in a sample grown under original conditions.