3 research outputs found
Self-formed Micro-Membranes
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 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
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.Comment: 8 pages, 4 figure