Ga2O3, a wide-band gap semiconductor, is of interest for high-power devices and deep-UV photodetectors. Many of these applications require the formation of heterostructures to create a conduction-band offset to confine charge carriers. This is commonly achieved through alloying with Al2O3. However, Al2O3 has a significantly smaller lattice constant than Ga2O3, which can introduce strain on the heterostructure. Experimentally, it has been difficult to grow Al2O3-Ga2O3 alloys with high Al content, so that the maximum achieved conduction-band offset is only around 0.33eV. High Al containing alloys are also difficult to n-type dope.
 

We use hybrid density functional theory simulations to design a heterostructure which closely matches the lattice constant of Ga2O3, while maintaining a conduction-band offset. We found that alloys of In2O3 and Al2O3 form a lattice-matched monoclinic structure with a 1 eV conduction-band offset [1]. Moreover, we show that this alloy can readily be n-type doped using Si [2]. We will also discuss the role of charge-carrier compensation by cation vacancies in Al2O3-Ga2O3 and In2O3-Al2O3 alloys.

[1] S. Seacat, J.L. Lyons, and H. Peelaers, Phys. Rev. Materials 8, 014601 (2024).
[2] S. Seacat and H. Peelaers, J. Appl. Phys. 135, 235705 (2024).