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Thurs., Jan. 19, 2012
10:30 a.m., NSERL 3.204








"Carbon Materials for Nanoelectronics and Energy Applications"
"Material Challenges in MEMS-based Mass Data Storage Chip"
Dr. Bin Shan and Dr. Rong Chen Huazhong, University of Science and Technology

Carbon-based nanostructures, including fullerenes, nanotubes, and more recently graphene, have drawn a lot of attention in the research community for their unique physical and electronics properties, as well as potential applications in nanoelectronics and energy storage areas. In recent years, on-going efforts have been made to fabricate hybrid carbon nanostructures in order to seek materials that may combine the advantages of individual components. These include carbon nanopeapods, carbon nanobuds, carbon triplets, and pillared graphene sheets. In this talk, Dr. Shan will discuss some of the recent works carried out in his group on the exploration of structural, energetic and electronic properties of such carbon hybrid nanostructures using first-principles methods. Nanobud is a novel hybrid carbon nanostructure synthesized recently by covalently attaching fullerene to the sidewall of single-wall carbon nanotubes. The most favorable cycloadditions configurations are determined and the results show the stabilities of nanobuds exhibit diameter and chirality dependence of the SWNTs. It is found that the C20 nanobuds are more stable than C60 nanobuds once formed. The band structure calculation suggests nanobuds' bandgaps are tunable by controlling the density of C20 outside the wall. Carbon triplets are another type of nanostructure that forms chemical bonds between the reactive ends of ultra-small tubes and have potential applications in hydrogen storage.

Abstract II
Flash memory chips are predicted to begin slowing down their bit density growth in the next few years due to lithography related constraints. A new class of ultra-high-capacity storage system based on MEMS technology, the probe-based seek-and-scan memory is an ideal candidate for future ultrahigh-density (>Tbit/inch2) nonvolatile memory devices. It uses a nano-probe array technology, read and write every domain onto a continuous ferroelectric media. The domains are defined by the electrical contact area of the AFM tip on the media, typically in 10~20 nm diameter today and going much smaller in the future. This technology will enable the storage of tens of gigabytes of data per chip, at a substantially lower cost than today’s flash memory solutions, and can potentially go far beyond the expected limits of conventional lithography used in present semiconductor memory chips. However, the high-speed scanning operations over a device lifetime of 5 to 10 years, which corresponds to a probe-tip sliding distance of 5 to 10km, can cause the probe-tip to mechanically wear, critically affecting its write-read resolution. In this talk, we will show that atomically smooth ferroelectric films are a prerequisite for both wear reduction and ultrahigh density recording. We show that a platinum-iridium probe-tip retains its write-read resolution on such surfaces over 5 km of sliding at a 5 mm/s velocity. This tip-wear endurance is enabled by applying a low magnitude modulated force at the tip-surface contact in the presence of a thin water layer. We also demonstrate a 3.6 Tbit/inch2 storage density over a 1×1 µm2 area, which is the highest density ever written on ferroelectric films over such a large area.

Dr. Bin Shan is a professor in materials science department at Huazhong University of Science and Technology (HUST), with specialty in computational materials science and microscopic modeling. His research interests is in the rational design of nanostructures for energy and clean-technology applications, including
carbon-based nanostructures for nanoelectronic and energy applications, simulation of nanoscale catalytic processes and the development of accurate empirical potentials for alloy nanoparticles, lithium ion and lithium air batteries, with a few papers published on PRL, APL, PCCP, JPC etc. The PdAu diesel engine catalyst Dr. Shan helped designing and developing has gone into commercial production, and is recoganized as one of the most innovative products of year 2010.

Dr. Shan started his academic career at Tsinghua University, P.R.China, graduating with honors in 2001 with a physics major. Shan obtained his doctoral degree in Applied Physics and Ph.D minor in Electrical Engineering from Stanford University, California in 2006. Dr. Shan joined Nanostellar Inc. after graduation and worked as a senior research scientist in the computational nanoscience division for five years. He joined HUST in 2010 and is now leading the Laboratory of Advanced Materials Design at HUST.

Dr. Rong Chen received her doctoral and master degrees from Stanford University and bachelor degree from University of Science and Technology of China (USTC). She joined school of mechanical science and engineering, Huazhong University of Science and Technology (HUST) in September, 2011. Prior to that, she was a senior research scientist in Intel Labs, conducting research on novel devices for electronics and energy applications. She was among the first batch of researchers awarded the young 1000 talent program -the Recruitment Program of Global Experts- granted by Organization Department of the CPC Central Committee, and the new century talents in universities support.

Dr. Chen’s research interests include nanostructured materials and devices to address emerging challenges in electronic and energy fields, with specialties in synthesizing and manipulating nanostructures with well defined chemical composition, atomic-scale precise structure control, and specific functional device application. Dr. Chen is the recipient of the Simon Karecki award from Semiconductor Research Corporation. She is now a council member of the Chinese Ceramic Society, thin film and coating division, senior member of Chinese Mechanical Engineering Society, member of IEEE, MRS, ACS, APS, and ECS. She also served as a technical advisor for Intel Capital and Intel Academic Research Office, an invited Proposal Study Panel reviewer for Lawrence Berkeley National Laboratory, and an invited reviewer for several distinguished international journals.