Metalorganic Chemical Vapor Deposition and Material Characterization of Lattice-Matched InAlN/GaN Two-Dimensional Electron Gas Heterostructures

Abstract

InAlN/GaN two-dimensional electron gas (2DEG) heterostructures were successfully grown by metalorganic chemical vapor deposition. X-ray photoelectron spectroscopy and X-ray diffraction measurements revealed that the barrier layer consists of a ternary In0.18Al0.82N alloy, a composition nearly lattice-matched to GaN. The bandgap energy of the In0.18Al0.82N barrier layer was estimated to be approximately 4.3 eV by spectroscopic ellipsometry analysis. Electrical characterization results showed that 2DEG mobility can be improved with the insertion of a thin AlN layer at the InAlN/GaN heterointerface. Very high 2DEG densities of more than 2.6×1013 cm-2 and high 2DEG mobilities of 1170 cm2/(V s) were achieved for InAlN/AlN/GaN structures with the barrier thickness of more than 15 nm. These 2DEG properties are almost equal to the best ones ever reported for InAlN/GaN 2DEG structures.