We report ultra-wide bandgap (UWBG) AlGaN heterostructure field-effect transistors (HFETs) exhibiting a high breakdown field (> 5.3 MV/cm) and a low contact resistance (~1.55 {\Omega}mm), tailored for high-power radiofrequency applications. A split-doped barrier architecture, employing two distinct doping concentrations, is shown to enhance both the breakdown field and contact resistance. This design enables a state-of-the-art combination of maximum drain current (487 mA/mm) and breakdown field, along with a high cutoff frequency of 7.2 GHz. These results demonstrate a viable pathway to push device performance toward the material limits while minimizing contact resistance in UWBG AlGaN HFETs, paving the way for next-generation high-power, high-frequency applications.
@article{arxiv.2509.15715,
title = {Barrier Electrostatics and Contact Engineering for Ultra-Wide Bandgap AlGaN HFETs},
author = {Seungheon Shin and Can Cao and Jon Pratt and Yinxuan Zhu and Brianna A. Klein and Andrew Armstrong and Andrew A. Allerman and Siddharth Rajan},
journal= {arXiv preprint arXiv:2509.15715},
year = {2025}
}