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 Ti2.5O3/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 Ti2.5O3 (0 1 0) film can be grown layer by layer on GaAs (0 01) 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 Ti2.5O3 layer, the integrated BaTiO3(250 nm)/SrTiO3/Ti2.5O3(5 nm)/GaAs heterostructure exhibits an enhanced hysteresis loop with a remnant polarization of 9.85 mu C/cm(2) at 600 kV/cm and a small leakage current density of 1 x 10(-5) A/cm(2) at -500 kV/cm, The considerable advantage of this Ti2.5O3/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. (C) 2019 Elsevier Inc. All rights reserved.