Solid phase epitaxy in nanoscale confined geometries: Geometry-Tuned Transport and Light–Matter Interfaces

Lateral solid-phase epitaxy (SPE) in oxides provides defect- and orientation-engineered functionality at the nanoscale, motivating transport-led device studies beyond structural characterization. Using nanoscale confined SPE, we crystallize amorphous LaAlO₃ exclusively inside lithographically defined nanocavities on SrTiO₃, producing wafer-scale arrays of coherent LAO/STO interfaces (billions per cm²) via block-copolymer lithography. We pattern the interface at ~10–20 nm lateral scales so that the two-dimensional electron gas (2DEG) is discretized into a periodic network of quantum-confined channels; four-probe measurements on as-crystallized samples show low sheet resistance across the patterned area. We will report how cavity diameter and pitch modulate the sheet resistance by tuning lateral quantum confinement (sub-band quantization and occupancy), carrier density, and inter-cavity tunneling. Building from earlier lateral-SPE seeding in SrTiO₃, which established controllable rotation and defect microstructures as a new handle on oxide properties, we use that paradigm to seed and rationalize the nanopatterned LAO/STO transport response. Finally, we outline application paths: reconfigurable nano-oxide electronics and integrated light–matter platforms where SPE-defined, nanoscale ferroelectric/plasmonic elements enable strong electro-optic coupling for quantum transduction.