Fall 2017

DSN-I Seminar "State of the Nanofab"

Speaker(s): 
Multiple Speakers
Dates: 
Wednesday, December 13, 2017 - 12:00pm to 1:30pm

As a premier multidisciplinary, open, and shared research lab, the Carnegie Mellon Nanofabrication Facility, or Nanofab, is a nanomanufacturing hub that plays a vital role in major research thrusts for the College and the University, namely in Information Technology, Internet of Things, Energy, and Life Sciences. The Nanofab serves a broad community at Carnegie Mellon and beyond, providing equipment, services, and process support for the invention, synthesis, and fabrication of new materials and devices in the areas of magnetics and spintronics, MEMS and NEMS, optics and photonics, functional oxides, 2-dimensional materials, bioelectronics, and much more. This talk will focus on the current state of the Nanofab as it relates to both research, equipment capabilities and user interface. In particular, we will highlight the transformative impact that the new Claire and John Bertucci Nanotechnology Laboratory will have for the CMU community and the region. The new facility will play a critical role in facilitating housing of cutting-edge nanomanufacturing equipment as well as creating new synergies and means for research collaboration across campus. We will discuss these new capabilities and some of the future initiatives we would like to purse to revolutionize nanoscale science and engineering within Carnegie Mellon and the region.

Where are hot carriers created in plasmonically enhanced semiconductor substrates?

  • By Burcu Ozden
  • 5 December 2017

PQI members Hrvoje Petek, Jin Zhao and their colleagues investigated a less known fact about the microscopic details of how the combined optical, electronic and chemical properties of metal/semiconductor interfaces define the coupling of light into the electronic reagents on their recent paper published in Nature Photonics. In this study, they investigated the coherence and hot electron dynamics in a prototypical Ag nanocluster/TiO2 heterojunction via ultrafast two-photon photoemission (2PP) spectroscopy, scanning tunneling microscopy (STM) and density functional theory (DFT).  The silver nanoclustors used in this study were grown via e-beam evaporation of Ag on top of TiO2 surface.They have shown that the plasmon excitation, dephasing and hot electron processes that are related to plasmonically enhanced photocatalysis involve complex physical and chemical interactions, with strong interfacial character involving the chemical and plasmonic coupling of Ag nanoclusters and the TiO2 substrate that cannot be predicted by the properties of the component materials, but rather require an understanding of their interactions. They found that the dephasing of the perpendicular and parallel plasmons by the dielectric screening response of the TiO2 substrate generates hot electrons with anisotropic and non-thermal distributions.

Interview with Dr. Pedram Roushan

Speaker(s): 
Pedram Roushan
Dates: 
Friday, December 1, 2017 - 10:00am to 11:00am

Pedram Roushan was born and raised in Iran. In 2001, he moved to the US as a religious refugee and attended Pitt, where he graduated summa cum laude in 2005. During his years at Pitt, he worked at the laboratories of X. L. Wu and W. Goldberg, focusing on the dynamics in 2D fluids. He received his PhD in 2011 from Princeton University, performing the first scanning tunneling microscopy on the surface of topological insulators in the lab of A. Yazdani. After three years of post-doctoral studies in the J. Martinis lab at the University of California, Santa Barbara, in 2014 he joined the Google quantum hardware lab aiming on making a quantum computer. The current focus of his research is on simulating condensed matter systems with engineered quantum platforms.

From Quantum Mechanics to Force Fields

  • By Burcu Ozden
  • 22 November 2017

Ken Jordan and his colleague are invited to write a special topic issue in the journal of chemical physics (JCP). This work is dedicated to the ongoing efforts of the theoretical chemistry community to develop a new generation of accurate force fields based on data from high-level electronic structure calculations and to develop faster electronic structure methods for testing and designing force fields as well as for carrying out simulations. 

What molecular properties give rise to a strong piezoelectric response?

  • By Burcu Ozden
  • 22 November 2017

In this study Geoffrey R. Hutchison and his colleagues tried to answer the question of " What molecular properties give rise to a strong piezoelectric response?"  To do so, they systematically probe the interplay among peptide chemical structure, folding propensity, and piezoelectric properties, uncovering in the process new insights into the origin of peptide electromechanical response. They have designed variety of peptides and peptoids and test the effect of molecular properties on piezoelectric response via serious measurements including ircular dichroism (CD), Polarization-modulated infrared reflection−absorption spectroscopy (PM-IRRAS), tomic force microscopy (AFM), piezo-force microscopy (PFM), and X-ray photoelectron spectroscopy (XPS) measurements. They showed backbone rigidity is an important determinant in peptide electromechanical responsiveness. 

Emergent Phenomena at Oxide Interfaces

Speaker(s): 
Dennis Christensen
Dates: 
Friday, December 8, 2017 - 3:00pm

The plethora of fascinating properties observed in oxide heterostructures has attracted a lot of interest. Most noticeably, the confined electron gas formed at the interface between the two insulators LaAlO3 and SrTiO3 features e.g. gate-tunable superconductivity, ferromagnetism and non-volatile memory effects. Numerous studies have been devoted to understanding the origin of the conductivity along with enhancing its properties. Recently, we found that substituting LaAlO3 with γ-Al2O3 can produce a confined electron gas with an electron mobility exceeding 100,000 cm2/Vs. Here, I show that...

New Era in Thermal Scanning Probe Lithography

  • By Burcu Ozden
  • 15 November 2017

Tevis Jacobs and his collaborators from IBM and SwissLitho were achieved sub-10 nanometer feature size in Silicon using thermal scanning probe lithography. In this work, they  the t-SPL parameters that influence high-resolution patterning on the transfer stack and demonstrate that sub-15 nm half-pitch resolution patterning and transfer by t-SPL are feasible. They found that the resolution in t-SPL is limited by the extent of the plastic zone in thermo-mechanical indentation on the pattern transfer stack because, at temperatures approaching the resist’s decomposition temperature, the line shape widens, reducing the achievable resolution. They achieved reliable transfer of patterned dense lines down to 14 nm half-pitch and in the best case 11 nm half-pitch. Furthermore, evidently they showed that an enhanced resolution below 10 nm half-pitch might be possible on a mechanically different transfer stack.

On systems with and without excess energy in environment

Speaker(s): 
Lorenz Cederbaum 
Dates: 
Monday, November 20, 2017 - 11:00am

How does a microscopic system like an atom or a small molecule get rid of the excess electronic energy it has acquired, for instance, by absorbing a photon? If this microscopic system is isolated, the issue has been much investigated and the answer to this question is more or less well known. But what happens if our system has neighbors as is usually the case in nature or in the laboratory? In a human society, if our stress is large, we would like to pass it over to our neighbors. Indeed, this is in brief what happens also to the sufficiently excited microscopic system. A new mechanism of...

NASA Workshop on Quantum Computing for Aeroscience and Engineering

  • By Leena Aggarwal
  • 15 November 2017

November 7-8, 2017, physics students and scientist from diffrent places were arrived at the NASA Langley research center for attending Quantum Computing workshop.

The objective of this workshop was to bring together experts on quantum information science and computation to understand the latest developments and current challenges in algorithms, hardware, and technology transition to engineering applications. The aims of workshop was to accelerate technology transition towards outstanding engineering problems that were expected to be achievable using quantum computations in the coming decade. The workshop’s goals were included developing a roadmap for success towards solution strategies for engineering applications. The interested stakeholders were presented or taken part in discussion on challenges to transition the current state-of-the-art to large scale engineering and data science related problems. 

 

Discussions were focused on the following four areas:

  • Quantum algorithms
  • Quantum computing hardware
  • Manufacturing and control of quantum systems
  • Engineering applications

Atomic Layer Semiconductor 2D Nanoelectromechanical Systems (NEMS)

Speaker(s): 
Philip Feng
Dates: 
Tuesday, December 12, 2017 - 3:00pm

Atomically thin semiconducting crystals derived from new classes of layered materials have rapidly emerged to enable two-dimensional (2D) nanostructures with unusual electronic, optical, mechanical, and thermal properties.  While graphene has been the forerunner and hallmark of 2D crystals, newly emerged 2D semiconductors offer intriguing, beyond-graphene, attributes.  The sizable and tunable bandgaps of compound and single-element 2D semiconductors offer attractive perspectives for strong multiphysics coupling and efficient transduction across various signal domains.  ...

Pages