Controlled Electrochemical Intercalation of Graphene/h-BN van der Waals Heterostructures

TL;DR

This study introduces a controlled electrochemical method to intercalate lithium ions into graphene/h-BN heterostructures, enabling precise tuning of electronic properties and high carrier densities while avoiding surface reactions.

Contribution

It presents a novel electrochemical strategy for intercalating lithium into vdW heterostructures with encapsulated graphene, monitored by Hall effect and spectroscopic techniques.

Findings

Achieved carrier densities > 5×10^{13} cm^{-2}

Observed Shubnikov-de Haas oscillations at low temperatures

Demonstrated high mobility > 10^3 cm^2/(Vs) in intercalated samples

Abstract

Electrochemical intercalation is a powerful method for tuning the electronic properties of layered solids. In this work, we report an electro-chemical strategy to controllably intercalate lithium ions into a series of van der Waals (vdW) heterostructures built by sandwiching graphene between hexagonal boron nitride (h-BN). We demonstrate that encapsulating graphene with h-BN eliminates parasitic surface side reactions while simultaneously creating a new hetero-interface that permits intercalation between the atomically thin layers. To monitor the electrochemical process, we employ the Hall effect to precisely monitor the intercalation reaction. We also simultaneously probe the spectroscopic and electrical transport properties of the resulting intercalation compounds at different stages of intercalation. We achieve the highest carrier density $> 5 \times 10^{13} cm^{-2}$ with mobility $> 10^3 cm^2/(Vs)$ in the most heavily intercalated samples, where Shubnikov-de Haas quantum oscillations are observed at low temperatures. These results set the stage for further studies that employ intercalation in modifying properties of vdW heterostructures.