Performance Evaluation of GaN-Based HEMTs with Cu Trap Layer Using Multi-Stacked AlGaN Barriers

This work presents a comprehensive performance evaluation of GaN-based High Electron Mobility Transistors (HEMTs) fabricated on a SiC substrate, incorporating a multistacked AlGaN barrier and a copper (Cu) trap layer. The device structure includes graded AlGaN layers-Alo.soGao.soN, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{Al}_{0.35} \text{Ga}_{0.65} ~\mathrm{N}$</tex>, and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{Al}_{0.20} \text{Ga}_{0.80} ~\mathrm{N}$</tex>-along with a GaN channel and spacer to enhance polarization-induced 2DEG formation and carrier confinement. A Cu-doped buffer layer is introduced to generate deep-level traps, effectively suppressing buffer leakage and improving thermal stability. The DC and RF performance metrics such as threshold voltage, drain current, transconductance, cutoff frequency, and breakdown voltage are analyzed to understand the influence of Cu doping on overall device behavior. Results confirm that <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{C u}$</tex> is an efficient trap material, maintaining carrier mobility while enhancing electrical reliability. This makes it a promising approach for high-power and high-frequency GaN-based HEMT applications.