Design Optimization of Strain Distribution and Polarization-Induced 2DEG Formation in III-Nitride/GaN Heterostructures

Abstract Gallium Nitride (GaN)-based High Electron Mobility Transistors (HEMTs) employ polarization-induced two-dimensional electron gas (2DEG) formation to achieve high carrier mobility and excellent high-frequency performance. While ferroelectric barriers such as Aluminium Scandium Nitride (AlScN) have demonstrated superior performance compared to conventional AlGaN barriers, limitations including the high cost of scandium, limited availability, structural instability above 30% Sc composition, and challenges associated with MOCVD growth motivate the exploration of alternative materials. In this work, Aluminium Yttrium Nitride (AlYN), Scandium Gallium Nitride (ScGaN), and Gallium Yttrium Nitride (GaYN) are systematically investigated as barrier layers for GaN-based HEMTs. The influence of barrier composition and interlayer engineering on strain, band alignment, and carrier confinement is analyzed. Among the investigated materials, AlYN exhibits the strongest carrier confinement and the highest electron density, reaching approximately 5.93 × 1013 cm−2 at 14% Y and 5.332 × 1013 cm−2 at 8% Y composition. The optimum AlYN barrier thickness is found to lie between 8 and 10 nm, and the incorporation of an AlN interlayer increases the electron density from 5.07 ×1013 cm−2 to 5.52×1013 cm−2. These results identify AlYN as a promising barrier material for next-generation GaN HEMTs, offering high carrier concentration, moderate strain, and enhanced design flexibility compared to existing Sc-based barrier technologies.