Upcoming Events

5th Annual CNM Users Meeting
May 7-9, 2008
To be held in conjunction with Argonne Users Week

Seminars

Archives: 2008 | 2007 | 2006 | 2005 | 2004 | 2003

May 1, 2008
10: 00 a.m.
Bldg 440, A105 & A106

"Synthesis and Tailoring the Surface Chemistry of Nanostructured Carbon Materials for Applications in Micro/Nano Systems," Anirudha V. Sumant, Argonne National Laboratory, hosted by Derrick C. Mancini

Abstract: The current progress in fabricating microelectromechanical and nanoelectromechanical systems (MEMS/NEMS) involving rotating, sliding, or impacting surfaces in contact based on silicon has achieved limited success primarily due to the poor mechanical, chemical, and tribological properties of silicon. At the nanoscale, due to increased surface-to-volume ratio, surface properties, such as adhesion/stiction dictates the performance of a device, and therefore development of new materials with superior mechanical, chemical, and tribological properties than those of silicon are necessary. Nanostructured carbon materials such as ultrananocrystalline diamond (UNCD) and tetrahedral amorphous carbon (ta-C) have demonstrated exceptional physical, chemical, and tribological properties at the macro- and microscale, and therefore are considered promising materials for MEMS and NEMS applications. However, little is known about their surface chemistry, morphology, and bonding configuration at the tribological interface and how it will affect tribological performance at the nanoscale. I will discuss methodologies to tune surface chemistry, morphology, and bonding configuration of UNCD surface via changes in the UNCD nucleation and growth process. Using these methodologies, we achieve extremely low adhesion energies (down to van der Waal's limit) and friction forces at the nanoscale.

Additionally, recent preliminary measurements of nanomechanical properties of UNCD carried out using in situTEM nano-indentation will also be presented. In case of ta-C, I will discuss how film-annealing processes alter both the bonding in the film and the nanotribological response.

In the next part of my talk, I will discuss current progress in synthesizing large area UNCD films (up to 8-in diameter) at low temperatures (400°C) at CNM and demonstration of its CMOS compatibility with a goal to develop monolithically integrated UNCD based MEMS/NEMS devices driven by CMOS. I will present work under progress in this direction on the fabrication of RF-MEMS switches based on UNCD by taking advantages of its unique dielectric properties as well as on the fabrication of UNCD based resonators by integrating with piezoelectric materials. At the end of my talk, I will present brief highlights of research that is being carried out under collaborative CNM user's proposal that I have developed with various outside collaborators.

May 2, 2008
10:00 a.m.
Bldg 440, A105-A106

"Nanomechanical switching at 1 ns and 1 V using an in-plane switch," David Czaplewski, Sandia National Laboratories, hosted by Derrick C. Mancini

Abstract: Nanomechanical switches have been proposed to replace CMOS switches to operate at temperatures greater than 200°C and with almost no static power dissipation. Ideally, the NEMS switches would be integrated with standard CMOS to realize power savings in computing applications. Ideally, to realize this goal, the switches would switch at similar voltages and with similar times to their CMOS counterparts. For integration purposes, the NEMS switch fabrication would have to be CMOS compatible.

This presentation will summarize the progress of the work on a program to create a nanomechanical switch that switches in 1 ns using 1-V drive actuation. A summary of the modeling effort will show the critical parameters of the design for fast, stable switching while avoiding mechanical failures of the switch. Then the fabrication performed to realize these devices will be shown. Finally, electrical testing results will be presented on the switches that have been fabricated and released.

Colloquium Series

The Center for Nanoscale Materials holds a regular biweekly colloquium on alternate Wednesday afternoons at 4:00 p.m. in Bldg. 440, Room A105/106. The goal of the series is to provide a forum for topical multidisciplinary talks in areas of interest to the CNM and also to offer a mechanism for fostering interactions with potential facility users. Refreshments will be served at 3:45.

Archive

April 30, 2008

"Nanoscale assembly using conditions far from equilibrium," Heinrich Jaeger, University of Chicago, hosted by Seth Darling

Abstract: Far from equilibrium conditions open up a range of new possibilities for forming structures on the nanometer scale. This talk will explore two situations where such conditions can be utilized to self-assemble nanoparticles. The first deals with the selective metal decoration of diblock copolymer scaffolds, while the second concerns drying-mediated nanoparticle assembly. Both situations deal with structures in the range of 5 to 50 nm that is difficult to tackle with conventional approaches.

May 14, 2008
4:00 p.m.
Bldg. 440, A105-A106

"Probing molecular-level organizational structure and electronic properties of weakly surface bound metallic nanoparticles, chiral domains, and single biomolecules," Thomas Pearl, North Carolina State University, hosted by Seth Darling

Abstract: Mechanisms of adsorption and organization of organic molecules on metallic surfaces play a significant role in the growth of chemically and electronically tuned, monolayer thin films. Intercommunication between functional groups for individual adsorbates can serve as the primary driving force for monolayer crystallinity as well as electronic structure especially in the limit of weak interaction between the adsorbate and substrate. In this talk, I will present a series of examples involving weakly bound surface species probed with high-spatial-resolution scanning tunneling microscopy (STM) and spectroscopy. As a first example, data will be discussed regarding spectral diffusion features for ligand encapsulated Au11 nanoparticles supported and isolated on alkanethiolate monolayers. The bulk of the work presented will involve submonolayer ordering of a chiral molecule, tartaric acid (C4H6O6), weakly bound to an achiral metal surface, Ag(111), as studied with low-temperature STM and density functional theory. Molecularly resolved images of enantiomerically pure (R,R)- and (S,S)-tartaric acid domains on Ag(111) will be presented, and the role of intermolecular hydrogen bonding in stereospecific domain and superlattice formation will be addressed. Additionally, we will consider chiral domain formation and phase separation from a racemic mixture of tartaric acid enantiomers. Lastly, we will present differential conductance mapping of tartaric acid molecular domains that highlight an intrinsic decoupling of molecular film electronic states with respect to the metallic lattice. While the chiral expression that drives the formation of enantiomeric domains does not induce stereospecific conductance, we demonstrate electronic differentiation of submonolayer organic domains from the Ag(111) surface. Density functional theory calculations will be discussed as they relate to both the molecular organization as well as the deconvolution of electronic structure between the molecular film and the metallic substrate. Finally, I will also highlight recent work in our group involving the study of functionalized, single- and double-stranded DNA molecules anchored to both metallic and ferroelectric surfaces.

May 28, 2008

"The Spin on Electronics!," Stuart Parkin, IBM Almaden Research Center, hosted by Matthias Bode

Abstract: Today, nearly all microelectronic devices are based on storing or flowing the electron¹s charge. The electron also possesses a quantum mechanical property termed "spin" that gives rise to magnetism. Electrical current is comprised of "spin-up" and "spin-down" electrons, which behave as largely independent spin currents. The flow of these spin currents can be controlled in thin-film structures composed of atomically thin layers of conducting magnetic materials separated by nonmagnetic conducting or insulating layers. The resistance of such devices, so-called spin valves and magnetic tunneling junctions, respectively, can be varied by controlling the relative magnetic orientation of the magnetic layers, giving rise to magnetoresistance tailored for different applications. Recent advances in generating, manipulating, and detecting spin-polarized electrons and electrical current make possible new classes of spin-based sensor, memory, and logic devices, generally referred to as the field of spintronics. In particular, the spin valve is a key component of all magnetic hard-disk drives manufactured today and has enabled their nearly thousandfold increase in capacity over the past eight years. The magnetic tunnel junction allows for a novel, high-performance random-access solid-state memory that maintains its memory in the absence of electrical power. The respective strengths of these two major classes of digital data storage devices, namely the very low cost of disk drives and the high performance and reliability of solid-state memories, may be combined in the future into a single spintronic memory-storage technology, the magnetic Racetrack. The Racetrack is a novel three-dimensional technology that uses nanosecond long pulses of spin polarized current to move a series of magnetic domain walls along magnetic nanowires.

June 11, 2008

"Semiconductor spintronics (Just the facts), Nitin Samarth, The Pennsylvania State University, hosted by Anand Bhattacharya

July 9, 2008

Cathy Murphy, University of South Carolina, hosted by Xiao-Min Lin

August 6, 2008

Eric Pop, University of Illinois at Urbana-Champaign, hosted by Jana Zaumseil

August 20, 2008

Clemens Burda, Case Western Reserve University

September 3, 2008

Claude Henry, Universite Marseille & CiNaM, hosted by Stefan Vajda

September 17, 2008

Raghuveer Parthasarathy, University of Oregon, hosted by Xiao-Min Lin

October 1, 2008

Zhonglin Wang, Georgia Tech, hosted by Xiao-Min Lin

October 8, 2008

"Organizing atoms, clusters, and proteins on surfaces," Richard Palmer, University of Birmingham, hosted by Stefan Vajda

October 15, 2008

Paul Russo, Louisiana State University, hosted by Seth Darling and Nathan Ramanathan

CNM Journal Club

The biweekly CNM journal club meetings are held on Wednesday afternoons at 4:00 p.m., alternating with the CNM colloquium series. The goal of CNM Journal Club is to provide an informal setting to share and discuss recent (or not so recent) papers that may be of general interest to others. If you are interested in suggesting a paper for the future journal club meetings, please e-mail Xiaohua Wu.