Controlled high-quality interface of a Ti_2.5O₃(0 1 0)/GaAs(0 0 1) heterostructure enabled by minimized lattice...

Metal oxide/semiconductor heterostructures exhibit great potential for high-performance electronic device applications, but the interfacial defects resulting from lattice mismatch pose significant challenges to improving the performance of these devices. In this study, we reported a construction of a single crystal Ti_2.5O₃/GaAs heterostructure with minimum lattice mismatch between titanium sub-oxides and GaAs substrate. Low lattice mismatch values of 0.3% or 0.6% can be achieved along different orientations. Further experimental analyses demonstrate that high crystalline Ti_2.5O₃ (0 1 0) film can be grown layer by layer on GaAs (0 0 1) substrate with highly compatible interface. The defect-free interface significantly suppresses the diffusion of As and Ga ions, which impedes the formation of arsenic oxide and gallium oxide at the interface. Due to the high-quality Ti_2.5O₃ layer, the integrated BaTiO₃(250 nm)/SrTiO₃/Ti_2.5O₃(5 nm)/GaAs heterostructure exhibits an enhanced hysteresis loop 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. The considerable advantage of this Ti_2.5O₃/GaAs heterostructure provides an example of integrating other functional oxides for GaAs with suppressed ion diffusion. It also provides a platform for fabricating different electronic devices with higher reliability and performance.