The integration of freestanding oxide heterostructures onto non-native substrates has recently highlighted oxide membranes as a promising platform for electronic applications. While strain-driven spalling is well established in semiconductor systems, its extension to complex oxides has so far been limited to proof-of-principle demonstrations under fixed pulsed laser deposition (PLD) conditions. Here, we show that strain-driven spalling of freestanding oxides membranes can be systematically tuned through a fluence - oxygen-pressure process map. By correlating growth parameters with cracking behavior, membrane release, and microstructure-probed by reflection high-energy electron diffraction, optical microscopy, scanning electron microscopy, and transmission electron microscopy-we identify well-defined growth windows that enable reproducible membrane formation and clarify the physical mechanisms governing oxide spalling. Furthermore, we demonstrate that this approach is compatible with the fabrication of more complex heterostructures, constituted by epitaxial tri-compounds overlayer on STO, highlighting the possibility of designing functionalized spalled membranes. We also show that epitaxial spalling can be extended to alternative substrates beyond conventional perovskites. Overall, these results establish epitaxial spalling as a growth-controlled route to freestanding oxide micromembranes, enabling increased structural complexity within a single high-yield fabrication process.

Submitted to ACS Applied Materials & Interfaces (2026)