The design-construction interface of Ti₂.₅O₃ (010)/GaAs (001): minimizing the lattice mismatch and impeding ions diffusions

Feasible interface lattice design is a really key issue for a high-quality hybrid of functional oxide thin films on GaAs semiconductor substrates. But interfacial defects induced by lattice mismatch cause the problem to become challenging. Here, we reported a novel sub-titanium oxide (Ti₂.₅O₃) thin film epitaxially grown on GaAs substrate using pulsed laser deposition, the high-quality Ti₂.₅O₃/GaAs heterostructure significantly reduced the lattice mismatch between titanium sub-oxides and the GaAs substrate. Besides, our work theoretically and experimentally demonstrated that high crystalline Ti₂.₅O₃ (010) film can be grown layer-by-layer on GaAs (001) substrate with highly compatible interfaces. Extremely low lattice mismatch values of 0.3% and 0.6% along different orientations can be achieved in combination with the notably suppressed formation of arsenic oxides (AsOx) and gallium oxides (GaOx) between Ti₂.₅O₃/GaAs interfaces. Owing to the favorable interface and high crystalline, integrated BaTiO₃(250 nm)/STO/Ti₂.₅O₃/GaAs heterostructure demonstrates hysteresis loops with a remnant polarization of 9.85 µC/cm² at 600 kV/cm and a small leakage current density of 1×10−5 A/cm² at -500 kV/cm. Not only the excellent performances pave the path for the further application of Ti₂.₅O₃/GaAs heterostructure in electronics, but also the unique strategy gives a good inspiration for coupling other functional oxides on GaAs with expected excellent performances.