Development of Quaternary InAlGaN Barrier Layer for High Electron Mobility Transistor Structures

A quaternary lattice matched InAlGaN barrier layer with am indium content of 16.5 ± 0.2% and thickness of 9 nm was developed for high electron mobility transistor structures using the metalorganic chemical-vapor deposition method. The structural, morphological, optical and electrical properties of the layer were investigated planning realization of microwave power and terahertz plasmonic devices. The measured X-ray diffraction and modeled band diagram characteristics revealed the structural parameters of the grown In_0.165Al_0.775Ga_0.06N/Al_0.6Ga_0.4N/GaN heterostructure, explaining the origin of barrier photoluminescence peak position at 3.98 eV with the linewidth of 0.2 eV and the expected red-shift of 0.4 eV only. The thermally stable density of the two-dimension electron gas at the depth of 10.5 nm was experimentally confirmed to be 1.2 × 10¹³ cm^-2 (1.6 × 10¹³ cm^-2 in theory) with the low-field mobility values of 1590 cm²/(V·s) and 8830 cm²/(V·s) at the temperatures of 300 K and 77 K, respectively.