Theoretical insights into the interface performance of Ga2O3/ZnO heterostructure photodetectors driven by polarization and strains

• Polarization directions and strains can regulate the interface performances of the β -Ga 2 O 3 /wurtzite ZnO heterostructures. • Strained heterostructures show different band alignment, built-in electric field, and interfacial carrier density. • −4% biaxial strains with polarization in the (0001) direction make heterostructures as the candidate for photodetectors. Enhancing hole density and the built-in electric field intensity is crucial for improving the responsivity and response speed of self-powered solar-blind ultraviolet photodetectors. In this study, we employ first-principles calculations to investigate the structural and interfacial electronic properties of β -Ga 2 O 3 /wurtzite ZnO ( w -ZnO) heterostructures, focusing on the effects of spontaneous polarization directions and strains in w -ZnO. Our findings reveal that applying −4 % biaxial strain along the a - c axes in w -ZnO results in a strained heterostructure comprising β -Ga 2 O 3 (1 0 0) and w -ZnO (0 0 0 1) with significant improvements. These include a more stable interface with −1.33 eV Å −2 formation energy, a direct 2.91 eV bandgap, type-Ⅱ band alignment with 1.90 eV conduction band offset and 0.38 eV valence band offset, a stronger 88.37 meV Å −1 built-in electric field, and enhanced interfacial hole density with 2.27 × 10 15 cm −2 . This study provides a theoretical foundation for the design and optimization of β -Ga 2 O 3 -based photodetectors.