Two-dimensional materials are flexible, transparent, compatible with living systems, and can enable new devices and physics based on their unique properties. One unique property is the ability of 2D crystals a single atom thick to undergo massive amounts of strain without failure. Since strain also drastically modifies the band structure leading to large changes in transport and optical properties, strain engineering of 2D crystals has the potential to create new devices, explore transport in pseudo-magnetic fields, and tune tunneling or excitonic effects. Graphene is the most well-studied of 2D crystals, and shows a strain-induced pseudo vector potential that can lead, in certain circumstances, to pseudo-magnetic fields. Recent work shows strain allows one to tune the band gap in transition metal dicalchognides, another class of 2D crystals. In this colloquium, we will explore strain by suspending 2D crystal membranes of graphene and hexagonal boron nitride over microchambers, creating a sealed drum. Tuning the strain through pressure deflects the membrane, changing its properties. Remarkably, the assumption of a fixed circumference is wrong, because we observe the 2D crystal sliding across the supported part of the microchamber. We will discuss friction, strain engineering, and future prospects for 2D crystals.

Goldberg is a Professor of Physics, Professor of Electrical and Computer Engineering, Professor of Biomedical Engineering, and Professor of Education. He is a former chair of the Physics Department and his active research interests are in the general area of nano-optics and spectroscopy for hard and soft materials systems. With colleagues, he has studied graphene and other 2D crystals, exploring strain and friction. He has worked in near-field imaging, developed subsurface solid immersion microscopy for Si inspection, and imaging through strongly scattering media. His group is working on novel approaches to subcellular imaging, biosensors and single virus imaging.

Goldberg is Director of Boston University's Center for Nanoscience and Nanobiotechnology, an interdisciplinary center that brings together academic and industrial scientists and engineers in the development of nanotechnology with applications in materials and biomedicine. He is director of BU’s nanomedicine program, bringing engineers and physical scientists together with medical researchers and clinicians.

Goldberg is the inaugural Director of STEM Education Initiatives in the Office of the Provost, working with colleges, departments and faculty in course transformation toward increasing the amount of evidence-based and active-learning in STEM instruction, and in developing and implementing training in teaching and learning for STEM PhD’s and postdocs, our nations future faculty.

Department of Physics General Colloquia

Researchers should cite this work as follows:

• Bennett Goldberg (2014), "Strain Engineering of 2D Crystals," https://nanohub.org/resources/20879.

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