Integration of functional nanoscale vias with LaAlO3/SrTiO3 (LAO/STO) heterostructures

LaAlO3/SrTiO3 (LAO/STO) heterostructures exhibit a high mobility 2D electron gas (2DEG) at the interface, which comes with many interesting physical properties, including superconductivity, ferromagnetism, ferroelasticity, tunable spin orbit coupling, and many more [1]. Under certain conditions, a metal/insulator transition emerges, which can be locally and reversibly controlled using either conductive AFM lithography (c-AFM) [1] or ultra low voltage e-beam lithography (ULV-EBL) [2]. Here we describe a method for incorporating other nanomaterials with LAO/STO using “nanovias”, which are nanoscale regions where the LAO layer is etched away. The nanovias can be used to host other quantum dots with direct electrical contact to the 2DEG. Having the ability to pattern the nanovias in any desired 2D pattern using EBL allows for many applications including nanomaterials spectroscopy. As a demonstration, we describe efforts to create 2D networks of superconducting NbTiN nanoislands, where the nanoislands could be weakly linked using LAO/STO conducting nanowires to form an array of superconductor–normal–superconductor (SNS) junctions [3].