Nanoscale ferroelectric programming of van der Waals heterostructures

TL;DR

This paper introduces a top-down nanoscale ferroelectric programming method for van der Waals heterostructures, enabling precise, resist-free patterning of electronic phases with potential for 10 nm resolution and new functionalities.

Contribution

It presents a novel ultra-low-voltage electron beam lithography technique to program ferroelectric domains in vdW heterostructures, allowing arbitrary nanoscale patterning of electronic phases.

Findings

Demonstrated ferroelectric field effects creating a lateral p-n junction

Achieved spatial resolution down to 35 nm with current methods

Predicted 10 nm resolution with future improvements

Abstract

The ability to create superlattices in van der Waals (vdW) heterostructures via moir\'e interference heralded a new era in the science and technology of two-dimensional materials. Through precise control of the twist angle, flat bands and strongly correlated phases have been engineered. The precise twisting of vdW layers is in some sense a bottom-up approach--a single parameter can dial in a wide range of periodic structures. Here, we describe a top-down approach to engineering nanoscale potentials in vdW layers using a buried programmable ferroelectric layer. Ultra-low-voltage electron beam lithography (ULV-EBL) is used to program ferroelectric domains in a ferroelectric Al_{1-x}B_{x}N thin film through a graphene/hexagonal boron nitride (hBN) heterostructure that is transferred on top. We demonstrate ferroelectric field effects by creating a lateral p-n junction, and demonstrate spatial resolution down to 35 nm, limited by the resolution of our scanned probe characterization methods. This innovative, resist-free patterning method is predicted to achieve 10 nm resolution and enable arbitrary programming of vdW layers, opening a pathway to create new phases that are inaccessible by moir\'e techniques. The ability to "paint" different phases of matter on a single vdW "canvas" provides a wealth of new electronic and photonic functionalities.