A Facile Vector Substrate Platform via BaTiO₃ Membrane Transfer Enables High-Quality Solution-Processed Epitaxial PZT...

The direct integration of high-performance ferroelectric oxides with silicon remains challenging due to lattice mismatch, thermal incompatibility, and the need for high-temperature epitaxial growth. Here, a hybrid integration approach is demonstrated in which crystalline BaTiO₃ (BTO) membranes are first transferred onto Pt-coated Si substrates and subsequently used as vector substrates (VS) for the growth of epitaxial (001) Pb(Zr_0.52Ti_0.48)O₃ (PZT) thin films via chemical solution deposition (CSD). A KI + HCl based etchant enables rapid and complete dissolution of the SrVO₃ sacrificial layer in ≈30 min, reducing the release time from days to minutes compared with conventional water-based approaches to dissolve AVO₃/AMoO₃ (A = Ca, Sr, Ba). The BTO VS imposes dominant (00l) out-of-plane orientation and in-plane cube-on-cube epitaxy in the overlying PZT. Devices exhibit P_r ≈ 10-12 µC cm^-2 and E_C ≈ 100 kV cm^-1, with stable switching to 10⁸ cycles on the VS. From piezoelectric butterfly loops, the study extracts $d_{33}^{effective}$ ​ ≈ 70 pm V^-1 for PZT on VS and ≈54 pm V^-1 for PZT grown on conventional Pt-Si substrates. The approach establishes a general pathway for transferring crystalline oxides to any arbitrary substrate and employing them as vector substrates for epitaxial integration of functional oxides.