title: Directing Matter: Toward Atomic-Scale 3D Nanofabrication.
abstract: Enabling memristive, neuromorphic, and quantum-based computing as well as efficient mainstream energy storage and conversion technologies requires the next generation of materials customized at the atomic scale. This requires full control of atomic arrangement and bonding in three dimensions. The last two decades witnessed substantial industrial, academic, and government research efforts directed toward this goal through various lithographies and scanning-probe-based methods. These technologies emphasize 2D surface structures, with some limited 3D capability. Recently, a range of focused electron- and ion-based methods have demonstrated compelling alternative pathways to achieving atomically precise manufacturing of 3D structures in solids, liquids, and at interfaces. Electron and ion microscopies offer a platform that can simultaneously observe dynamic and static structures at the nano- and atomic scales and also induce structural rearrangements and chemical transformation. The addition of predictive modeling or rapid image analytics and feedback enables guiding these in a controlled manner. Here, we review the recent results that used focused electron and ion beams to create free-standing nanoscale 3D structures, radiolysis, and the fabrication potential with liquid precursors, epitaxial crystallization of amorphous oxides with atomic layer precision, as well as visualization and control of individual dopant motion within a 3D crystal lattice. These works lay the foundation for approaches to directing nanoscale level architectures and offer a potential roadmap to full 3D atomic control in materials. In this paper, we lay out the gaps that currently constrain the processing range of these platforms, reflect on indirect requirements, such as the integration of large-scale data analysis with theory, and discuss future prospects of these technologies.
authors.forename: Stephen
authors.initials: S
authors.lastname: Jesse
authors.forename: Albina Y
authors.initials: AY
authors.lastname: Borisevich
authors.affiliation: Department of Materials Sciences, University of Tennessee , Knoxville, Tennessee 37996, United States.
authors.forename: Jason D
authors.initials: JD
authors.lastname: Fowlkes
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Lupini
authors.affiliation: Department of Materials Sciences, University of Tennessee , Knoxville, Tennessee 37996, United States.
authors.forename: Philip D
authors.initials: PD
authors.lastname: Rack
authors.forename: Raymond R
authors.initials: RR
authors.lastname: Unocic
authors.forename: Bobby G
authors.initials: BG
authors.lastname: Sumpter
authors.forename: Sergei V
authors.initials: SV
authors.lastname: Kalinin
authors.forename: Alex
authors.initials: A
authors.lastname: Belianinov
authors.forename: Olga S
authors.initials: OS
authors.lastname: Ovchinnikova
keywords: atom dynamics; atomic manipulation; direct-write; helium ion microscopy; nanofabrication; nanolithography; scanning electron microscopy; scanning transmission electron microscopy