Spatial control of the conductivity in SrTiO3-based heterointerfaces using inkjet printing

Interfaces between complex oxides host a plethora of functional properties including enhanced ionic conductivity, gate-tunable superconductivity and exotic magnetic states. The enhanced electronic, ionic and magnetic properties along the oxide interfaces are generally exploited in functional devices by spatial confinement of ions and electrons. Different patterning methods have been used to spatially control the conductivity at the interface, but a key limitation is the multiple steps needed to fabricate functional devices. In this investigation, inkjet printing of thermally stable oxides is introduced as an alternative pathway for spatially controlling the interface conductivity. We inkjet print yttrium-stabilized zirconia and TiO2 with various shapes and use these as physical masks to confine the electronic conductivity in SrTiO3-based heterostructures. By performing in-situ transport measurements of the electrical conductivity as LaAlO3 and gamma-Al2O3 are deposited on SrTiO3, we witness the birth of the interface conductivity and find a consistent transient behavior as conductivity emerges in patterned and non-patterned heterostructures. We find that conductivity appears after the first laser pulse in the pulsed laser deposition corresponding to the film covering only a few percent of the substrate. We attribute the emergence of conductivity to oxygen vacancies formed by a combination of plasma bombardment and oxygen transfer across the interface during growth. In this vein, inkjet patterned hard masks protects the SrTiO3 substrate, effectively confining the conductivity. The study paves a scalable way for realizing energy devices with spatially controlled electronic and ionic interface conductivity.