Deep-UV bleaching of charge disorder in encapsulated graphene

TL;DR

Deep-UV exposure significantly improves the electronic quality of encapsulated graphene by neutralizing charged impurities, enabling advanced quantum phenomena observation.

Contribution

Demonstrates that brief deep-UV exposure enhances graphene quality by neutralizing impurities, revealing new quantum states and phenomena.

Findings

Two orders of magnitude increase in electronic quality after UV treatment

Observation of fractional quantum Hall states, including non-Abelian candidates

Recovery of transport properties in previously unusable devices

Abstract

Disorder masks much of the rich physics in two-dimensional electronic systems, with charged impurities often the limiting factor. In graphene, progress in reducing disorder has largely stagnated since boron nitride encapsulation was introduced a decade ago. Here we show that a brief deep-UV exposure enhances the electronic quality of encapsulated graphene - typically by two orders of magnitude - by neutralizing charged impurities within boron nitride. Following illumination, standard graphene devices exhibit numerous evendenominator fractional quantum Hall states, including non-Abelian candidates, and frequently reveal hidden superlattice minibands. Even macroscopically inhomogeneous devices, seemingly unusable for transport studies, recover after deep-UV illumination and display Landau quantization in millitesla fields. This finding provides a straightforward route to exceptional-quality graphene, enabling further exploration of interaction-driven, topological and other quantum phenomena.