van der Waals epitaxy of lead monoxide - PbO and application as a virtual substrate for oxide membranes

TL;DR

This paper demonstrates the growth of van der Waals epitaxial lead monoxide layers as virtual substrates for oxide membranes, enabling controlled exfoliation and transfer of high-quality oxide films, advancing free-standing membrane fabrication.

Contribution

It introduces PbO as a novel virtual substrate for vdW epitaxy, facilitating easy exfoliation and transfer of oxide films with high crystal quality, surpassing traditional methods.

Findings

PbO can be epitaxially grown on various substrates.

PbO layers enable controlled spalling and exfoliation of oxide films.

High-quality oxide films can be transferred using tape methods.

Abstract

We report the successful growth of epitaxial layers of van der Waals (vdW) lead oxide (PbO) polymorphs on different substrates, via pulsed laser deposition. A thin layer of vdW ${\alpha}$-PbO (~5 nm) was subsequently used as a virtual substrate to grow thin films of perovskites BaTiO$_3$, SrTiO$_3$, and the spinel CoFe$_2$O$_4$ with a crystal quality comparable to direct epitaxy on single-crystal oxide substrates. Notably, films with the larger lattice parameter underwent spontaneous, controlled spalling within days of growth, remaining structurally intact, or were easily exfoliated and transferred using the tape method. This work establishes PbO as a promising virtual substrate technology for the fabrication of free-standing oxide membranes through vdW epitaxy, offering advantages over conventional sacrificial layer methods.