MRI: Acquisition of a 3D Tomographic Atom-Probe Microscope

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Technical Summary: An Atom Probe Tomography (APT) Microscope is a new material analysis instrument that provides the only technique that can obtain both three-dimensional (3D) tomographic images and chemical identification at the atomic scale. It provides insight into key problems in the materials science, chemistry, physics and engineering of nanoscale structures and devices. The APT Microscope uses a rapidly pulsed electric field from a local electrode to remove atoms individually from the sample; the atom mass is determined by the time of flight to an imaging detector array. These 3D tomographic images can identify the element, and even the isotope, of individual atoms. They enable the spatial mapping of structural defects, dopants, and atomic structure and composition in nanowires, patterned materials, heterostructures and devices. The ability to completely visualize a material directly is new, and it opens a new range of investigations and applications. This proposal asks for funds to acquire a 3D APT Microscope for installation in the Center for Nanoscale Systems at Harvard University. The APT Microscope will promote collaborations between physicists, chemists, and device developers with materials scientists by allowing them to examine spatially modulated structures at the atomic scale. This information is particularly important for nanoscale devices for electronics and photonics, where atomic scale interfaces determine the behavior of the device. This instrument can be used to understand the structure of materials at the atomic level, including complex oxide semiconductors that are promising for future electronics, solar cells and fuel cells. The installation of a Atom-Probe Tomography Microscope in the Center for Nanoscale Systems at Harvard University will provide direct and open access for researchers and educators in the Northeast region of the United States. It will provide opportunities for to a diverse population of students. An innovative educational program "Nanoscale Imaging and Analysis" will use the APT Microscope to integrate research into the teaching of materials science, physics and chemistry at the undergraduate, graduate and adult levels.Layman Summary: To make and understand atomic-scale structures, we must be able to both image the location of individual atoms in a structure and identify their chemical identity. Atom Probe Microscopy is the only technique that provides this information. A three-dimensional image displays the atoms, and different colors can be used to show which element they are. By creating images that are easy to understand, an Atom Probe Microscope will allow us to make and understand truly small atomic scale devices for computation, communication, energy production, and medical treatment. The instrument operates by using a rapidly pulsed electric field to remove an individual atom from the sample - the time of flight to the imaging detector determines the mass of each atom. The images can identify the element, and even the isotope, of each atom, as well as its location. The Atom-Probe Microscope will be installed in the Center for Nanoscale Systems at Harvard University, and provide direct and open access for researchers and educators in the Northeast region of the United States - it will enhance the education of a diverse population of students. This new instrument will allow researchers to understand the atomic structure of new electronic and optical devices, create new types of solar cells and fuel cells to ease the national energy problem, and fundamentally study the structure of materials at the atomic level.