Towards more efficient power transistors: Modulation-Doped β-(AlₓGa₁₋ₓ)₂O₃/Ga₂O₃ heterostructures with enhanced electron mobility

Semiconductor-based power electronics is a key technology for solving the greatest challenge facing society - sustainable energy generation. This challenge is to be tackled by developing modulation-doped β-(AlxGa1-x)2O3/Ga2O3 heterostructures with high electron mobility for highly efficient power transistors. In Ga2O3 in particular, this approach to increase the charge carrier mobility promises a high innovation potential, as it was also theoretically predicted that the significantly limiting scattering process on polar-optical phonons would be screened. If this scattering process is suppressed, a similar charge carrier mobility is expected in Ga2O3 as in silicon, as the effective electron mass is similar. Effective screening of polar-optical phonons only occurs at a carrier density in the two-dimensional electron gas (2DEG) around 1013 cm-2, which requires a conduction band discontinuity of at least 1 eV. Theoretical predictions show that this requires an aluminum content of at least 50% (x ≥ 0.5) in the barrier. This structure has not yet been realized and is to be developed for the first time in the All-GO-HEMT project. The requirements for high crystalline perfection, a homogeneous layer thickness and smooth interface with a high Al content and delta doping over the entire substrate size of up to 2 inches must be met to provide a material basis for more efficient power electronics.