A Radical Tool for 3D Atomically Precise Sculpting

A Radical Tool for 3D Atomically

Precise Sculpting Graphic shows the proposed mechanochemical reaction in which a highly reactive radical atom tool is used to remove an atom from the apex of a silicon scanning Atomically precise manufacturing probe microscopy (SPM) tip (gold atoms on top). Irradiation of a surface-bound (APM) is an emerging disruptive tech- molecule with ultraviolet light (1) forms an atomic radical (purple) (2). As the SPM tip nology that could dramatically reduce approaches the reactive molecule within a few tenths of a nanometer (3), the reactive molecule forms a chemical bond with an atom on the SPM tip and pulls it off (4). energy use and increase performance Graphic image courtesy of University of California at Los Angeles. of materials, structures, devices, and finished goods. Using APM, every of the process, the SPM tip can be used in Benefits for Our Industry and atom is at its specified location rela- imaging mode to help detect and remove Our Nation defects. Unlike a sculpting knife, during tive to the other atoms—there are no this type of mechanosynthesis, the tool is Assembly techniques capable of defects, missing atoms, extra atoms, stationary and the SPM tip being sculpted atomic-level precision, such as 3D or incorrect (impurity) atoms. Like moves in 3D with a precision measured mechanosynthesis, will accelerate the development of tools and processes for other disruptive technologies, APM in tenths of a nanometer. This project aims to develop a reproducible proof-of- manufacturing defect-free materials will first be commercialized in early principle mechanosynthetic approach for and products that offer new functional premium markets, such as nanoelec- fabricating atomically precise SPM tips qualities and ultra-high performance— tronics for quantum computing. that is ultimately extendable to making with the potential to dramatically reduce surface bound nano-products. This type the use of energy and materials. Such The ambitious goal of this project is of APM method has the potential to potentially groundbreaking technologies to mechanosynthesize structures in become a disruptive technology that is could also enable electronic and three dimensions (3D) for the first applicable to a broad range of products. material properties that are otherwise time. Mechanosynthesis is a radically unobtainable. These enhanced different manufacturing approach where The best SPM tip materials are those properties could benefit a broad range of atomically perfect structures are created that already are close to being atomically applications after entering early premium (synthesized) by directly moving atoms precise, such as crystalline materials. markets. (mechanically). To control chemical The best materials for the molecular reactions, precision movement in sculpting tool are high-energy, reactive Applications in Our Nation’s 3D must be controlled in tenths of a atoms on designer molecules that can nanometer. To date, mechanosynthetic pull atoms from the lattice of the single Industry techniques have only been used to make crystal SPM tip. Appropriate materials Some of the most promising applications two-dimensional (2D) structures. will be designed by a computer and then of atomically precise technology synthesized. Computational modeling include clean energy, water purification, In this project, a molecular tool is created is used to guide the precise trajectory next-generation computing and data that has a highly reactive (radical) atom required for the molecules of the SPM tip storage, and cybersecurity. Applications at its tip. This tool is moved like a lathe, to approach the reactive molecular tool. with high potential for scaling-up but rather than machining or cutting, it The tool will remove defect atoms and commercial use in the near-term include gently transfers atoms sequentially in the process is repeated until the target catalysts with specific structures for a 3D through a combination of mechanics structure is created. desired catalytic activity, membranes and special chemistry. The tool is used with greater selectivity and durability, to pull defect atoms from molecules and sensors to detect the presence of on the tip of an externally controlled chemical and biological trace molecules. scanning probe microscope (SPM). The These products are expected to include structure is being sculpted to make an new mechanical, photonic, electronic, atomically sharp tip for the SPM, an quantum, and sensory capabilities as well atomic-scale imaging tool. At each stage as other enhanced properties.

ADVANCED MANUFACTURING OFFICE ADVANCED MANUFACTURING OFFICE

Project Description a synergy of computational design Project Partners This project aims to demonstrate the modeling efforts, advanced instrument University of California at Los Angeles use of mechanosynthesis to produce and method development, as well as Los Angeles, CA an atomically precise SPM tip by validated experimental implementation Principal Investigator: Dr. James sequentially removing defect atoms via of SPM-based atomic manipulation will Gimzewski externally controlled 3D movement of the be leveraged throughout this project. The Email: [email protected] tip around a molecular tool anchored on a project is organized into three highly integrated and collaborative pathway surface. First, specific identified reactants For additional information, will be designed, synthesized, and areas: 1) computational modeling and utilized to control and selectively extract simulation to better understand both tip please contact atoms from the SPM tip, re-shaping it to and surface chemistry to produce surface- Tina Kaarsberg, PhD a predefined crystalline form. If proven, bound reactants for atomic abstraction; Technology Manager radical tool chemistry with atomically 2) instrument and method development U.S. Department of Energy precise (picometer) control of SPM tip’s to enable enhanced accuracy in tip Advanced Manufacturing Office movement will enable the fabrication of positioning and throughput; and 3) proof- Phone: 202-586-5112 other atomically precise 3D structures of-concept experimental implementation Email: [email protected]  on surfaces with designer functionality of SPM-based atomic manipulation. guided by computer simulation. Since lack of atomically precise SPM tips is a Milestones challenge for many APM processes, tips This two-year project began in July 2018: produced in this project would also be an important enabling technology for more • Achieve formation of activated, widespread use of APM. surface-bound reactants by SPM (2019)

• Demonstrate ability to use the selected Barriers reactant as a probe to image the SPM • Identifying tip materials of sufficient tip (2020) hardness and standardized surface chemistry for strongly reactant • Successful removal of atoms from the molecules for the tool tip through reactant-driven abstraction (2020) • Demonstrating a low-temperature SPM with simultaneous scanning tunneling microscope (STM) and frequency- Technology Transition modulation atomic force microscopy After successful demonstration of the (AFM) imaging capabilities tip-based atom removal process, the eventual goal is to develop atomically • Developing a chemical synthesis route precise assembly systems with for the reactant precursor materials multiple tips operating in parallel at the and scaling their production, first on physical limits of atomic and nanoscale the microscale and eventually in gram fabrication and measurements. In the quantities short term, this project will enable the SPM scientific community to work with • Demonstrating and characterizing tips of known structure. In the medium single atom transfer term, the developed technology can • Sequentially removing several atoms enable the manufacture of 3D structures from the SPM tip using known tips as well as have groundbreaking applications in metrology applicable to energy technologies. Pathways If these technical approaches are Today, scientists use SPMs to positionally successfully developed further, they assemble novel, laboratory-scale, could eventually lead to very fast atomically precise structures only in 2D. assembly systems with multiple tips In this work, major challenges include focusing on covalently bonded structures, the inability to make atomically precise which could broaden the commercial microscope tips, tip crashes, thermal application of APM. drift, achieving positional repeatability, For more information, visit: and the need for tenths of a nanometer energy.gov/eere/amo accuracy. To overcome these challenges, DOE/EE-1836 • September 2019