metal-insulator transition using ultra-low-voltage electron-beam lithography*

We describe a method to control the insulator-metal transition at the LaAlO₃/SrTiO₃ interface using ultra-low-voltage electron beam lithography (ULV-EBL). Compared with previous reports that utilize conductive atomic-force-microscope lithography (c-AFM), this approach can provide comparable resolution (~10 nm) at write speeds (10 mm/s) that are up to 10,000x faster than c-AFM. The writing technique is non-destructive and the conductive state is reversible via prolonged exposure to air. Transport properties of representative devices are measured at milli-Kelvin temperatures, where superconducting behavior is observed. We also demonstrate the ability to create conducting devices on graphene/LaAlO₃/SrTiO₃ and hBN/graphene/LaAlO₃/SrTiO₃ heterostructures. The underlying mechanism is believed to be closely related to the same mechanism regulating c-AFM-based methods.