Ga ₂ O ₃ /(Al)GaN Heterostructures for Next Generation Power Electronics

Gallium oxide (Ga 2 O 3 ) is an emerging semiconductor for high‐power electronics, but its low thermal conductivity, lack of viable p‐type doping, and limited carrier mobility restrict device performance and prevent high‐speed applications. This work presents a novel strategy to simultaneously mitigate the thermal and transport limitations of Ga 2 O 3 through heterojunctions with III‐nitride materials. Owing to their higher thermal conductivity and strong polarization fields, III‐nitrides can enhance heat dissipation and enable high‐density two‐dimensional electron gases (2DEGs) at the heterointerface, improving switching speed. The role of spontaneous and piezoelectric polarization in 2DEG formation is systematically examined. It is shown that Al‐polar AlN/ β ‐Ga 2 O 3 heterojunctions do not support 2DEG formation due to hole accumulation at the interface, whereas N‐polar AlN/ β ‐Ga 2 O 3 heterostructures are identified as promising candidates for high 2DEG densities. The band alignment of the AlN/ β ‐Ga 2 O 3 interface is also investigated. Additionally, κ ‐Ga 2 O 3 , recently identified as ferroelectric with strong polarization, is explored in κ ‐Ga 2 O 3 /AlGaN heterostructures. Using epitaxial layer and strain engineering, electron mobilities up to 691 cm 2 V −1 s −1 at 77 K were achieved in MOCVD‐grown κ ‐Ga 2 O 3 /N‐polar AlGaN/AlN heterostructures. These results highlight the potential of III‐nitride/Ga 2 O 3 heterostructures for high‐power and radiofrequency device applications with enhanced performance and efficiency.