Argonne National Laboratory

Seminar Series

Date Title

August 28, 2017

11:00 am

Bldg. 440, A105/A106

“Low-cost, high-performance, single-crystal-like device layers and controlled self-assembly of nanostructures within device layers for wideranging energy and electronic applications”, Amit Goyal, Director RENEW, The State University of New York.  Host: Supratik Guha.
 
For many energy and electronic applications, single-crystal-like materials offer the best performance. However, in almost all cases, fabrication of single-crystal form of the relevant material is too expensive. In addition, for many applications, very long or wide materials are required, a regime not accessible by conventional single-crystal growth. This necessitates the use of artificially fabricated, large-area, single-crystal-like substrates suitable for heteroepitaxial growth of the relevant advanced material for the electronic or energy application in question. In this talk, details of the fabrication of such substrates will be discussed. Heteroepitaxial growth of nanolaminate multilayers and devices on such substrates using a variety of deposition techniques such as pulsed laser ablation, sputtering, e-beam evaporation, MBE, MOCVD, and chemical solution deposition will be reported upon. Application areas that have been demonstrated via the use of such artificial substrates include – oxide high-temperature superconductors, semiconductor materials (Si, Ge, GaAs, CdTe, Cu2O), ferroelectrics (BaTiO3), multiferroics (BiFeO3), etc. In addition, strain-driven selfassembly of second phase nanomaterials at nanoscale spacings has been demonstrated within device layers. Control of heteroepitaxy in lattice-mismatched systems and the effects of strain on self-assembly will be discussed. Such heteroepitaxial device layers on large-area, singlecrystal-like
artificial substrates are quite promising for a range of electrical and electronic applications.
 

August 15, 2017

11:00 am

Bldg. 440, A105/A106

"Visualizing Nanoscale Dynamics in Liquids with High Spatial and Temporal Resolution Using Liquid Cell TEM", See Wee, Center for BioImaging Sciences, National University of Singapore.  Host:  Jianguo Wen

Liquid cell transmission electron microscopy is a powerful technique that allows to us visualize phenomena that take place in a liquid environment with the resolving power of a transmission electron microscope (TEM). In this presentation, I will show two examples of how liquid cell TEM can be used to study chemical reactions involving nanoparticles and the dynamics of nanoparticles. First, I will discuss results from experiments where we followed the microstructural evolution of Ag nanocubes as they undergo galvanic replacement with Au ions to understand mechanisms behind hollow structure formation. Second, I will talk about how we can track both the translation and rotation of nanoparticles contained within these liquid cells with temporal resolution of a few milliseconds. Lastly, I will discuss the potential impact of high speed direct electron cameras on the field. In particular, I will touch on the strategies we are developing at the Center for BioImaging Sciences to achieve low electron dose imaging conditions for our experiments and the challenges in working with the large datasets that result from these experiments.

 

August 14, 2017

10:00 am

Bldg. 440, A105-A106

"Four-Dimensional Ultrafast Electron Microscopy", Haihua Liu, Division of Chemistry and Chemical Engineering, California Institute of Technology.  Host: Tijana Rajh

The 4D UEM pioneered by Professor Ahmed Zewail at Caltech since 2004 enables scientist to explore ultrafast events and process that occur at the atomic-scale and in femtoseconds, which is 10 orders of magnitude better than that of conventional microscopes limited by the video-camera rate of recording. Now, 4D UEM has been used in the study of ultrafast dynamics from atomic motions during structural dynamics to ultrafast phase transitions, nanomechanical oscillations, chemical bonding dynamics, crystallization dynamics, charge density wave, plasmonics. Dr.  Liu is focusing on novel methodology development of 4D UEM and their applications in studying ultrafast dynamics of light-matter interactions. 

In this talk, Dr. Liu will introduce the development and progress that he made in 4D UEM, such as ultrafast phase transition dynamics of single particle vanadium dioxide embedded in ensemble, development of diffraction PINEM to improve energy resolution and study near field plasmon dynamics in the infrared range, photon-gating to improve temporal resolution in UEM, 4D multiple cathode UEM. 

August 11, 2017

11:00 am

Bldg. 440, A105-A106

"Nanophotonic materials by design: The case for refractory plasmonics", Urcan Guler, School of Electrical & computer Engineering and Brick Nanotechnology Center, Purdue University.  Host:  Daniel Lopez

Plasmonics studies the interaction of electric field with free electrons in metallic materials, which results in enhanced optical cross-sections. The field has attracted great attention due to the unprecedented ability to control light and its promise in a vast variety of scientific and technological applications such as sensing, energy harvesting, waveguiding, imaging, data storage, and medical therapies. However, material-related limitations and the strategic knowledge gap in alternative plasmonic materials research have been the major roadblocks. As with many other fields, plasmonics is now evolving into a multidisciplinary research area with a focus on materials development for application-specific requirements. In this talk, I will present a case study on transition metal nitrides as refractory plasmonic materials and their enabling role in applications that impose harsh environmental conditions. Energy harvesting, remote sensing in hot zones, photocatalysis, local heating and photothermal therapy will be discussed as prominent examples among many other opportunities. In the second part, I will discuss future directions for nanophotonic materials by design approach utilizing in situ and operando characterization techniques. Devices pushing the temporal and spatial limits bring new exciting challenges towards multifunctional systems made of nanoscale components. A detailed understanding of nanomaterials and their interfaces is a true challenge that is becoming a necessity to develop highly efficient nanoscale light sources, sensors, modulators, and energy harvesters for self- powered remote components that will form a network of multifunctional devices. Techno- economically feasible, self-sustaining systems will require highly efficient components made of earth abundant and process-compatible materials that can meet multiple environmental requirements often imposed by applications. The interaction of nanomaterials with local chemistry and external stimuli such as electromagnetic field, heat, electric signal, and mechanical load at the nanoscale forms the basis of a multiphysics system pushing the spatiotemporal, spectral, and intensity limits. A combinatorial approach for in situ and operando characterization and development of optical nanodevices for multifunctional systems will transform the internet of intelligent things covering a broad spectrum of arenas from smart cities to intra-body networks. The work will reveal fundamentally new insights to nanoscale phenomena and trigger new research questions both in the field of nanophotonics and other related areas where nanomaterials are the driving force.

August 11, 2017

3:00 pm

Bldg. 440, A105/A106

"Random Access Quantum Information Processors", Srivatsan Chakram Sundar, The University of Chicago. Host: Gary Wiederrecht.

Qubit connectivity is an important property of a quantum processor, with an ideal processor having random access -- the ability of arbitrary qubit pairs to interact directly. We describe the implementation of a random access superconducting quantum information processor, demonstrating universal operations on a nine-bit quantum memory, with a single superconducting transmon qubit serving as the central processor. The quantum memory uses the eigenmodes of a linear array of coupled superconducting resonators. The memory qubits are superpositions of vacuum and single-photon states, controlled by a single superconducting transmon coupled to the edge of the array. We show that single transmon charge control, and flux-driven sideband interactions with the cavity modes are sufficient for universal quantum control of the entire multimode manifold. We demonstrate universal gate operations between arbitrary pairs of modes, as well as efficient schemes for generating multi-photon entangled states. The fast and flexible control, achieved with efficient use of cryogenic resources and control electronics, in a scalable architecture compatible with state-of-the-art quantum memories in the form of high-Q 3D microwave cavities, is promising for quantum computation and simulation.

August 9, 2017

3:00 pm

Bldg. 440, A105/A106

"Quantum dots created by atom manipulation with the scanning tunneling microscope", Dr. Stefan Folsch, Senior Scientist, Paul-Drude-Institut fur Festkorpereletronik. Host:  Saw-Wai Hla
 
Atom manipulation with the scanning tunneling microscope (STM) makes it possible to create ultimately small structures at surfaces. We applied this technique to III-V semiconductor surfaces and found that their electrostatic potential landscape can be precisely designed by the controlled positioning of charged adatoms. In this way, quantum dots (QDs) with identical, deterministic sizes can be created one atom at a time. By using the lattice of the InAs(111)A surface to define the allowed atomic positions, the shape and location of the dots is controlled with effectively zero error. The dots are assembled from +1 charged indium adatoms, leading to the confinement of intrinsic surface-state electrons. This technique enables one to generate ultra-small QDs free of statistical variations in size and shape, providing error-free control of their energy level structure. The discussed results illustrate that atom manipulation in combination with scanning tunneling spectroscopy provides detailed insight into the quantum-physical properties of artificial surface structures at the smallest size scales. Understanding and controlling these properties – and the new kinds of behavior to which they can lead – will be crucial for integrating atomic-scale devices with existing semiconductor technologies.

August 8, 2017

11:00 am

Bldg. 440, A105/A106

"Direct Optical Lithogrpahy of Functional Inorganic Nanomaterials", Dmitri Talapin, The University of Chicago.  Host:  Daniel Lopez.

Photolithography is an important manufacturing process that relies on using photoresists, typically polymer formulations, that change solubility when illuminated with ultraviolet light. Here, we introduce a general chemical approach for photoresist-free, direct optical lithography of functional inorganic nanomaterials. The patterned materials can be metals, semiconductors, oxides, magnetic, or rare earth compositions. No organic impurities are present in the patterned layers, which helps achieve good electronic and optical properties. 

The conductivity, carrier mobility, dielectric, and luminescence properties of optically patterned layers are on par with the properties of state-of-the-art solution-processed materials. The ability to directly pattern all-inorganic layers by using a light exposure dose comparable with that of organic photoresists provides an alternate route for thin-film device manufacturing.