Achieving n-type doped monoclinic (InxAl1-x)2O3 alloys

Abstract

The monoclinic (In0.25Al0.75)2O3 alloy has been suggested as an ideal material to create monoclinic Ga2O3 heterostructures, as it provides a close lattice match to β-Ga2O3 along with a 1 eV conduction-band offset. Achieving intentional n-type doping in Ga2O3 heterostructures is important for device applications, but this may be difficult due to the high Al content of this alloy. Here, we use density functional theory with a hybrid functional to investigate common donor dopants, in particular, Si, Sn, C, and Ge substituting on cation sites, and H interstitials, in In2O3 and InAlO3. We identify Si as the optimal donor, as it is a shallow donor for In concentrations above 14%. Its formation energy is also low, indicating that these donors will incorporate during growth. For higher In concentrations, Sn (above 33% In) and Ge (above 35% In) are also promising donors, with Sn having comparable formation energies to Si.