A Facile Vector Substrate Platform via BaTiO ₃ Membrane Transfer Enables High‐Quality Solution‐Processed Epitaxial PZT on Silicon

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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics><mml:msubsup><mml:mi>d</mml:mi> <mml:mn>33</mml:mn> <mml:mrow><mml:mi>e</mml:mi> <mml:mi>f</mml:mi> <mml:mi>f</mml:mi> <mml:mi>e</mml:mi> <mml:mi>c</mml:mi> <mml:mi>t</mml:mi> <mml:mi>i</mml:mi> <mml:mi>v</mml:mi> <mml:mi>e</mml:mi></mml:mrow> </mml:msubsup> <mml:annotation>$d_{33}^{effective}$</mml:annotation></mml:semantics> </mml:math> ​ ≈ 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.