Cleaning interfaces in layered materials heterostructures

• Published in: Nature communications Vol. 9; no. 1; pp. 5387 - 12
• Main Authors: Purdie, D. G., Pugno, N. M., Taniguchi, T., Watanabe, K., Ferrari, A. C., Lombardo, A.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 19.12.2018; Nature Publishing Group; Nature Portfolio
• Subjects: 140/133; 147/3; 639/166/987; 639/301/1005/1007; 639/925/918/1052; Blistering; Blisters; Boron; Boron nitride; Chemical vapor deposition; Cleaning; Contaminants; Electronic devices; Electronic equipment; Fabrication; Graphene; Heterostructures; Humanities and Social Sciences; Interfaces; Layered materials; Materials science; multidisciplinary; Polymers; Polymethyl methacrylate; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-07558-3

Heterostructures formed by stacking layered materials require atomically clean interfaces. However, contaminants are usually trapped between the layers, aggregating into randomly located blisters, incompatible with scalable fabrication processes. Here we report a process to remove blisters from fully formed heterostructures. Our method is over an order of magnitude faster than those previously reported and allows multiple interfaces to be cleaned simultaneously. We fabricate blister-free regions of graphene encapsulated in hexagonal boron nitride with an area ~ 5000 μm 2 , achieving mobilities up to 180,000 cm 2  V −1  s −1 at room temperature, and 1.8 × 10 6  cm 2  V −1  s −1 at 9 K. We also assemble heterostructures using graphene intentionally exposed to polymers and solvents. After cleaning, these samples reach similar mobilities. This demonstrates that exposure of graphene to process-related contaminants is compatible with the realization of high mobility samples, paving the way to the development of wafer-scale processes for the integration of layered materials in (opto)electronic devices. Atomically-clean interfaces are required in heterostructures. Here, authors report a method for fast and parallel removal of contaminants from fully-formed heterostructures, including sample intentionally exposed to polymers and solvent, achieving room temperature mobility over 180,000 cm 2 /Vs for graphene.