Controlled Growth of a Line Defect in Graphene and Implications for Gate-Tunable Valley Filtering

Chen, J-H., G. Autés, N. Alem, Gargiulio, A. Gautam, M. Linck, A. Zettl, et al., 2014

Abstract

Atomically precise tailoring of graphene can enable unusual transport pathways and new nanometer-scale functional devices. Here we describe a recipe for the controlled production of highly regular “5-5-8” line defects in graphene by means of simultaneous electron irradiation and Joule heating by applied electric current. High-resolution transmission electron microscopy reveals individual steps of the growth process. Extending earlier theoretical work suggesting valley-discriminating capabilities of a graphene 5-5-8 line defect, we perform first-principles calculations of transport and find a strong energy dependence of valley polarization of the charge carriers across the defect. These findings inspire us to propose a compact electrostatically gated “valley valve” device, a critical component for valleytronics.

Impact Statement

A new procedure for executing a controlled production of highly regular “5-5-8” line defects in graphene. The procedure involves simultaneously conducting electron irradiation and Joule heating applied electrical currents. The researchers performed first-principles transport calculations and discovered that across the defect, the valley polarization of the charge carriers depends strongly on energy. Their observations led to the proposal of a compact, electrostatically gated “valley valve” device.