title: Epitaxy: Programmable Atom Equivalents Versus Atoms.
abstract: The programmability of DNA makes it an attractive structure-directing ligand for the assembly of nanoparticle (NP) superlattices in a manner that mimics many aspects of atomic crystallization. However, the synthesis of multilayer single crystals of defined size remains a challenge. Though previous studies considered lattice mismatch as the major limiting factor for multilayer assembly, thin film growth depends on many interlinked variables. Here, a more comprehensive approach is taken to study fundamental elements, such as the growth temperature and the thermodynamics of interfacial energetics, to achieve epitaxial growth of NP thin films. Both surface morphology and internal thin film structure are examined to provide an understanding of particle attachment and reorganization during growth. Under equilibrium conditions, single crystalline, multilayer thin films can be synthesized over 500 × 500 μm2areas on lithographically patterned templates, whereas deposition under kinetic conditions leads to the rapid growth of glassy films. Importantly, these superlattices follow the same patterns of crystal growth demonstrated in atomic thin film deposition, allowing these processes to be understood in the context of well-studied atomic epitaxy and enabling a nanoscale model to study fundamental crystallization processes. Through understanding the role of epitaxy as a driving force for NP assembly, we are able to realize 3D architectures of arbitrary domain geometry and size.
authors.forename: Mary X
authors.initials: MX
authors.lastname: Wang
authors.forename: Soyoung E
authors.initials: SE
authors.lastname: Seo
authors.affiliation: Department of Materials Science and Engineering, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Gabrys
authors.affiliation: Thomas J. Watson Laboratories of Applied Physics, California Institute of Technology , 1200 East California Boulevard, Pasadena, California 91125, United States.
authors.forename: Dagny
authors.initials: D
authors.lastname: Fleischman
authors.affiliation: X-ray Science Division, Argonne National Laboratory , 9700 South Cass Avenue, Argonne, Illinois 60439, United States.
authors.forename: Byeongdu
authors.identifier: 0000-0003-2514-8805
authors.initials: B
authors.lastname: Lee
authors.forename: Youngeun
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Thomas J. Watson Laboratories of Applied Physics, California Institute of Technology , 1200 East California Boulevard, Pasadena, California 91125, United States.
authors.forename: Harry A
authors.identifier: 0000-0001-9435-0201
authors.initials: HA
authors.lastname: Atwater
authors.affiliation: Department of Materials Science and Engineering, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Macfarlane
authors.forename: Chad A
authors.identifier: 0000-0002-6634-7627
authors.initials: CA
authors.lastname: Mirkin
keywords: DNA; epitaxy; nanoparticles; self-assembly; thin film