AVS 50th International Symposium
    Nanometer Structures Thursday Sessions
       Session NS-ThM

Paper NS-ThM1
Autonomous Atom Assembly*

Thursday, November 6, 2003, 8:20 am, Room 308

Session: Advances in Scanning Probes
Presenter: R.J. Celotta, National Institute of Standards and Technology
Authors: R.J. Celotta, National Institute of Standards and Technology
J.A. Stroscio, National Institute of Standards and Technology
A.P. Fein, National Institute of Standards and Technology
S.R. Blankenship, National Institute of Standards and Technology
A. Lacaze, National Institute of Standards and Technology
J. Cugini, National Institute of Standards and Technology
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The ability to use an STM to move and position atoms with lattice site precision provides us with a quantum workbench to study the effects of quantum confinement and the electronic structure of perfect nanostructures. So far, atomic manipulation has been performed manually, or with rudimentary computer assistance. In this talk, we describe an Autonomous Atom Assembler (AAA), which is an instrument capable of assembling a desired nanostructure from an unknown random collection of atoms without human intervention. It is based on an existing low temperature STM system, with hardware and software extensions. In operation, a dilute coverage of adsorbate atoms is deposited on a clean, flat substrate. The AAA then instructs the STM to image the random adsorbate pattern, identifies the position of each adsorbate atom relative to the substrate lattice, and plans a series of moves to place the available atoms at positions specified in a previously entered diagram. The plan minimizes construction time, follows a set of extensible rules, and allows for error correction. The AAA then instructs the STM to execute the plan and, upon completion, provide an image of the final assembled nanostructure. In our initial trials, Co atoms were deposited to a coverage of 0.003 monolayer on a Cu(111) substrate initially held at 7 K in UHV. Subsequent STM measurements were performed at a 4.3 K sample temperature. Simple confinement structures were autonomously assembled involving tens of atoms. We will report our first results, including the accuracy of positioning, speed of operation, reliability, and scalability of our design. * Supported in part by the Office of Naval Research