Structural, electrical, morphological, and interfacial characteristics of lattice-matched InAlN/GaN HEMT structure on SiC substrate

Abstract

This work highlights the influence of surface properties, on the characteristics of InAlN/GaN based high electron mobility transistor (HEMT) structures grown on the SiC substrate by metalorganic vapor phase epitaxy. The growth parameters, i.e., reactor pressure and V/III ratio were tuned to improve the morphological and two-dimensional electron gas (2DEG) characteristics of the HEMT structure. It was found that V/III ratio plays a significant role in improving surface morphology and 2DEG properties without altering average indium composition. It was also found that 2DEG properties are highly sensitive to surface morphology and its features. The step flow smooth surface morphology with very low surface and interface roughness was observed in optimized lattice-matched InAlN/GaN HEMT structures. The sheet resistance of ∼170 Ω/sq with good 2DEG concentration (∼2.4 × 1013 cm−2) and 2DEG mobility (∼1500 cm2/V s) was achieved in the optimized lattice-matched InAlN/GaN HEMT structure. A comparison between different barrier-based HEMT structures, i.e., lattice-matched InAlN/GaN and strained AlGaN/GaN, was also discussed. Their structural, electrical, morphological, and interfacial characteristics were compared.