High-Performance InSb-Based High-Electron-Mobility Transistors Grown on a GaAs Substrate

This work describes a comprehensive optimization strategy for high-performance InSb/InAlSb HEMT structures on GaAs substrates featuring both high two-dimensional electron gas (2DEG) concentration and mobility. The strategy begins with systematic simulations of the active region, including optimization of the Al composition in the InAlSb barrier layer to enhance 2DEG confinement and adjustment of the quantum well width to minimize intersubband scattering. A theoretical 2DEG concentration exceeding 1 × 1012 cm–2 with high mobility was predicted. Then, optimization of a buffer layer between GaAs and InSb was investigated. Double-crystal X-ray diffraction and atomic force microscopy indicated that 50 periods of InSb/In0.9Al0.1Sb superlattices can effectively relieve the lattice mismatch when directly deposited on the GaAs substrate. Inserting stressed In0.85Al0.15Sb layers within the thick In0.9AlSb buffer on one hand reduces the dislocation filtering efficiency and on the other suppresses the formation of microtwins (MTs). A dislocation density of 1.8 × 108 cm–2 was achieved in the InSb quantum well (QW) on an optimized 1.8 μm buffer layer. Finally, in the full-structure MBE growth process, by reducing the delta-doping temperature to 340 °C and incorporating a low-temperature InAlSb protective layer, we successfully fabricated an electrically optimized InSb HEMT structure with a 2DEG concentration of 1.9 × 1012 cm–2 and a mobility of 35,615 cm2/V·s.