Collaborative Research: Understanding the Formation and Separation of Nanoscale Contacts

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As the size of electronic devices shrinks to the nanometer scale, new technologies are required to manufacture and characterize them. Many of these new approaches rely on a nano-sized stylus selectively making contact with a surface, and then modifying or measuring the contacted region. The function, reliability, and precision of these techniques are determined by the properties of the contact, especially the adhesion force, the area of contact, and the deformation of the underlying material. This award supports fundamental research to understand the physics, chemistry, and materials science that govern the formation and separation of contacts at these length scales. The new insights into nanoscale contacts will guide the optimization of existing techniques and the development of novel approaches, helping to keep the U.S. at the forefront of advanced manufacturing and technology. The investigation is being conducted by an interdisciplinary team of researchers, and incorporates specific programs to include participation by people from underrepresented groups. Nanocontact behavior will be investigated for chemically and structurally diverse materials, with scientific and technological relevance. Nanocontact experiments will be conducted with in situ transmission electron microscopy that will provide nanonewton force resolution and Angstrom-scale structural information. The experiments will be complemented by molecular dynamics simulations of the same nanocontacts that provide atomic-scale detail about phenomena occurring within the materials and inside the perimeter of the contact, which cannot be viewed directly in experiment. These techniques will be used to characterize adhesion, deformation under load, and load-dependent contact area for a variety of contacts. Taken together, the data will enable evaluation of competing hypotheses that describe nanoscale contact. These insights will have direct impact on probe-based nanomanufacturing and on probe-based microscopy, both of which require precise understanding and control of the tip/sample contact. More generally, the in situ nanoscale testing in this program will yield insights that are relevant to larger-scale applications in which interfaces between materials consist of many nanoscale asperity contacts.