Materials behavior often begins at the atomic scale, making the understanding of how atomic systems behave of vital importance. Atomistic simulation techniques such as molecular dynamics and density functional theory have become instrumental in quantifying how the properties of atomic-level materials systems propagate to larger length and time scales and dictate observed materials behavior.
Moiré superlattices are formed when two van der Waals layers are stacked vertically with a controlled twist angle. Transition metal dichalcogenides (TMDs) are semiconductor building blocks with highly tunable optical properties. After reviewing some early studies, I will discuss the limitations of TMD-based moiré superlattices and propose twisted hBN substrates as a new approach to expand the strategy of moiré engineering to a broader range of photonic materials.
Quantum computing is a transformative technology that will change the world by quickly solving impossible problems, but its fundamental unit of information, the qubit, is nearly impossible to fabricate especially en masse with full functionality. Single crystal defects form the basis for solid-state qubits; they are materials, and their information is physical in nature requiring extreme precision in fabrication. This presentation introduce past fs work fabricating single defects in SiC and then it will expand on our very successful preliminary demonstration showing that a singl
With recent advances in detector technology and a new class of ptychographic phase-retrieval algorithms to unscramble multiple scattering, the resolution of the electron microscope is now limited only by the dose applied to the sample, and thermal vibrations of the atoms themselves. At high doses, these approaches have allowed us to image the detailed vibrational envelopes of individual atom columns as well as locating individual interstitial atoms.
In this talk, I will briefly introduce the molecular beam epitaxy (MBE) growth mechanism and then focus on my research, which centers on the MBE growth of quantum materials, spanning from topological materials to interfacial superconductors. I will talk about two solid-state phenomena with zero resistance: the quantum anomalous Hall (QAH) effect and the interface superconductivity. The QAH insulator is a material in which the interior is insulating but electrons can travel with zero resistance along one-dimensional conducting edge channels.
Topological nanowires, topological materials confined in 1D, hold great promise for robust and scalable quantum computing and low-dissipation interconnect applications, for which the desirable properties of topologically protected electronic states must be controlled. In this talk, I will discuss my group’s efforts to develop a precision synthesis method to fabricate 1D topological systems at high throughput. We employ thermomechanical nanomolding to extrude single crystal nanowires of topological materials with controlled diameters.
Progress in neural interfacing devices is transforming our understanding of the brain and the treatment of neurological conditions and injuries. As Richard Feynman famously claimed in 1959, “there’s plenty of room at the bottom” regarding nanotechnology, I argue that the same is true today about neural device engineering. In this talk, I will support this argument by presenting recent neuroelectronic advances from my group, all of which are enabled by fundamental innovations in materials and devices, often at the nanoscale.
Nature creates remarkable material by controlling the hierarchical assembly of molecules that are broken down at the end of their useful life. Inspired by natural systems, my group’s research combines molecular design with directed assembly via extrusion-based 3D printing to program the structure and function of polymer-based materials across length scales. First, I will describe how in both liquid crystalline polymers and block copolymers we can control the extent of nanostructure alignment and functional anisotropy via the flow history the material undergoes during 3DP.
Oxide semiconductors such as In₂O₃ and ZnO combine high electron mobility with a large breakdown field and optical transparency in the visible spectrum. Indium-based oxides retain these desirable properties even in the amorphous phase, a feature that enabled the commercial adoption of InGaZnO (IGZO) n-channel field-effect transistors in pixel driver circuits for flat-panel displays more than a decade ago. Building on this success, oxide semiconductors are now being explored for advanced logic and memory applications.
Materials are at the heart of everything in the semiconductor industry, from the cell phones in our pockets to the mainframes powering global financial transactions. This talk will highlight some of the key challenges and opportunities for materials engineering in leading-edge semiconductor architectures. State-of-the-art interconnects can be fabricated with atomic-level precision to co-optimize electrical performance and reliability. First-principles-based simulation can help us identify promising candidate materials for next-generation interconnect wiring.
