Self-formed $LaAl{O}_3/SrTi{O}_3$ Micro-Membranes

Abstract

Oxide heterostructures represent a unique playground for triggering the emergence of novel electronic states and for implementing new device concepts. The discovery of 2D conductivity at the $LaAl{O}_3/SrTi{O}_3$ interface has been linking for over a decade two of the major current research fields in Materials Science: correlated transition-metal-oxide systems and low-dimensional systems. A full merging of these two fields requires nevertheless the realization of $LaAl{O}_3/SrTi{O}_3$ heterostructures in the form of freestanding membranes. Here we show a completely new method for obtaining oxide hetero-membranes with micrometer lateral dimensions. Unlike traditional thin-film-based techniques developed for semiconductors and recently extended to oxides, the concept we demonstrate does not rely on any sacrificial layer and is based instead on pure strain engineering. We monitor through both real-time and post-deposition analyses, performed at different stages of growth, the strain relaxation mechanism leading to the spontaneous formation of curved hetero-membranes. Detailed transmission electron microscopy investigations show that the membranes are fully epitaxial and that their curvature results in a huge strain gradient, each of the layers showing a mixed compressive/tensile strain state. Electronic devices are fabricated by realizing ad hoc circuits for individual micro-membranes transferred on silicon chips. Our samples exhibit metallic conductivity and electrostatic field effect similar to 2D-electron systems in bulk heterostructures. Our results open a new path for adding oxide functionality into semiconductor electronics, potentially allowing for ultra-low voltage gating of a superconducting transistors, micromechanical control of the 2D electron gas mediated by ferroelectricity and flexoelectricity, and on-chip straintronics.

arXiv comment8 pages, 4 figures

References in corpus (16)

• Van der Waals heterostructures
• Signatures of Majorana fermions in hybrid superconductor-semiconductor nanowire devices
• Magnetic effects at the interface between nonmagnetic oxides
• Electric Field Control of the LaAlO${}_3$/SrTiO${}_3$ Interface Ground State
• Tunable Rashba spin-orbit interaction at oxide interfaces
• Spin-orbit qubit in a semiconductor nanowire
• High Mobility in LaAlO3/SrTiO3 Heterostructures: Origin, Dimensionality and Perspectives
• Highly efficient and tuneable spin-to-charge conversion through Rashba coupling at oxide interfaces
• Epitaxy of Semiconductor-Superconductor nanowires
• A Semiconductor Nanowire-Based Superconducting Qubit
• Photoferroelectric oxides
• Thickness dependence of the mobility at the LaAlO_3 / SrTiO_3 interface
• Imaging and tuning polarity at SrTiO3 domain walls
• Edge states and topological insulating phases generated by curving a nanowire with Rashba spin-orbit coupling
• Atomic layer engineering of perovskite oxides for chemically sharp heterointerfaces
• Tuning Pairing Amplitude and Spin-Triplet Texture by Curving Superconducting Nanostructures

Cited by in corpus (6)

• Strain-induced topological phase transition at (111) SrTiO${}_3$-based heterostructures
• Freestanding Thin-Film Materials
• Integration of High-Tc Superconductors with High Q Factor Oxide Mechanical Resonators
• Oxide Membranes from Bulk Micro-Machining of SrTiO${}_3$ substrates
• Freestanding single-crystal superconducting electron-doped cuprate membrane
• Leveraging high fluence and low pressure for pulsed laser deposition of high-mobility $\gamma$-Al${}_2$O${}_3$/SrTiO${}_3$ heterostructure growth