30 March - Optical contrast in ion-implanted amorphous silicon carbide nanostructures

Tomorrow Tania will present the following paper

Optical contrast in ion-implanted amorphous silicon carbide nanostructures,

J.Phys.D, 40 (2007) 7492-7496.

Topographic and optical contrasts formed by Ga+ ion irradiation of thin films of amorphous silicon carbide have been investigated with scanning near-field optical microscopy. The influence of ion-irradiation dose has been studied in a pattern of sub-micrometre stripes. While the film thickness decreases monotonically with ion dose,  the optical contrast rapidly increases to a maximum value and then decreases gradually. The results are discussed

in terms of the competition between the effects of ion implantation and surface milling by the ion beam. The observed effects are important for uses of amorphous silicon carbide thin films as permanent archives in optical data storage applications.

Finding the Missing Memristor - R. Stanley Williams

R. Stanley Williams from HP Labs gives a keynote presentation on memristor technology at the UC San Diego Center for Networked System's Winter Research Review 2010.

A stretchable carbon nanotube strain sensor for human-motion detection 

Takeo Yamada,1 Yuhei Hayamizu,1Yuki Yamamoto,1Yoshiki Yomogida,1Ali Izadi-Najafabadi,1Don N. Futaba1& Kenji Hata

Devices made from stretchable electronic materials could be incorporated into clothing or attached directly to the body. Such materials have typically been prepared by engineering conventional rigid materials such as silicon, rather than by developing new materials. Here, we report a class of wearable and stretchable devices fabricated from thin films of aligned single-walled carbon nanotubes. When stretched, the nanotube films fracture into gaps and islands, and bundles bridging the gaps. This mechanism allows the films to act as strain sensors capable of measuring strains up to 280% (50 times more than conventional metal strain gauges), with high durability, fast response and low creep. We assembled the carbon-nanotube sensors on stockings, bandages and gloves to fabricate devices that can detect different types of human motion, including movement, typing, breathing and speech.

Nature Nanotechnology Year published: (2011) DOI: doi:10.1038/nnano.2011.36

23 March - Silicon Oxide: A Non-innocent Surface for Molecular Electronics and Nanoelectronics Studies

Today Peiman will present the following paper:

Silicon Oxide: A Non-innocent Surface for Molecular Electronics and Nanoelectronics Studies 

Jun Yao†, Lin Zhong*‡§, Douglas Natelson*§, and James M. Tour*‡ J. Am. Chem. Soc., 2011, 133 (4), pp 941–948

DOI: 10.1021/ja108277r 

Nanoelectronics: Flat transistors get off the ground

• Frank Schwierz

Nature Nanotechnology

 

6,

 

135–136

 

(2011)

 

doi:10.1038/nnano.2011.26

Published online

 

04 March 2011

The presence of a large bandgap means that a single layer of molybdenum disulphide can be used to make field-effect transistors with high on/off ratios and reasonably high mobilities.

16 March - A fast and low-power microelectromechanical system-based non-volatile memory device

Today Harish will present the following paper

A fast and low-power microelectromechanical system-based non-volatile memory device
Sang Wook Lee, Seung Joo Park, Eleanor E. B. Campbell & Yung Woo Park

Nature Communications Volume 2, published 01 March 2011
Article number: 220 - DOI: doi:10.1038/ncomms1227

Several new generation memory devices have been developed to overcome the low performance of conventional silicon-based flash memory. In this study, we demonstrate a novel non-volatile memory design based on the electromechanical motion of a cantilever to provide fast charging and discharging of a floating-gate electrode. The operation is demonstrated by using an electromechanical metal cantilever to charge a floating gate that controls the charge transport through a carbon nanotube field-effect transistor. The set and reset currents are unchanged after more than 11 h constant operation. Over 500 repeated programming and erasing cycles were demonstrated under atmospheric conditions at room temperature without degradation. Multinary bit programming can be achieved by varying the voltage on the cantilever. The operation speed of the device is faster than a conventional flash memory and the power consumption is lower than other memory devices.

VSM

Today's reading group will be on the VSM. Andy will present a small introduction on this popular technique used to characterize magnetic properties of materials.

The vibrating sample magnetometer: Experiences of a volunteer
S. Foner - Francis Bitter National Magnet Laboratory and Department of Physics, MIT, Cambridge, Massachusetts 02139

On its 40th anniversary, I describe how the vibrating sample magnetometer ~VSM! was developed and, later, how the very low frequency VSM, a flux-integration device, was developed. The important features of the moving sample technique, detection coil symmetry, calibration, sensitivity, and image effects are discussed briefly. Some VSM adaptations discussed include operation at 3He and dilution refrigerator temperatures, at high hydrostatic pressures, in superconducting, high-power water-cooled and hybrid magnets, for very low frequency ac susceptibility, and with SQUID detectors. © 1996 American Institute of Physics. [S0021-8979~96!50508-4]

One Nanometer Resolution Electrical Probe via Atomic Metal Filament Formation

Seung Sae Hong†, Judy J. Cha‡, and Yi Cui*

Nano Lett., 2011, 11 (1), pp 231–235

DOI: 10.1021/nl103603v

Publication Date (Web): December 1, 2010

Scanning probe microscopy has been widely used to investigate various interactions in microscopic nature. Particularly, conductive atomic force microscopy (C-AFM) can provide local electronic signals conveniently, but the probe resolution of C-AFM has been limited by the tip geometry. Here, we improve the probe resolution greatly by forming an atomic-size metallic filament on a commercial C-AFM tip. We demonstrate 1 nm lateral resolution in C-AFM using the metal filament tip. The filament tip is mechanically robust and electrically stable in repeated scans under ambient conditions since it is imbedded in a stable insulating matrix. The formation of the atomic filament is highly controllable and reproducible and can be easily integrated to existing AFM tip technologies to produce the next generation of high-resolution electrical and other scanning probes.

Silicon Oxide: A Non-innocent Surface for Molecular Electronics and Nanoelectronics Studies

Jun Yao†, Lin Zhong*‡§, Douglas Natelson*§, and James M. Tour*‡

J. Am. Chem. Soc., 2011, 133 (4), pp 941–948

DOI: 10.1021/ja108277r

Publication Date (Web): December 22, 2010

Silicon oxide (SiO_x) has been widely used in many electronic systems as a supportive and insulating medium. Here, we demonstrate various electrical phenomena such as resistive switching and related nonlinear conduction, current hysteresis, and negative differential resistance intrinsic to a thin layer of SiO_x. These behaviors can largely mimic numerous electrical phenomena observed in molecules and other nanomaterials, suggesting that substantial caution should be paid when studying conduction in electronic systems with SiO_xas a component. The actual electrical phenomena can be the result of conduction from SiO_xat a post soft-breakdown state and not the presumed molecular or nanomaterial component. These electrical properties and the underlying mechanisms are discussed in detail.

02 March - High-Resolution Transmission Electron Microscopy Study of Electrically-Driven Reversible Phase Change in Ge2Sb2Te5 Nanowires

Today Jorge will present the following paper:

High-Resolution Transmission Electron Microscopy Study of Electrically-Driven Reversible Phase Change in Ge₂Sb₂Te₅ Nanowires

Yeonwoong Jung, Sung-Wook Nam, and Ritesh Agarwal

Nano Lett., Article ASAP

DOI: 10.1021/nl104537c

By combining high-resolution transmission electron microscopy (HRTEM) characterization and electrical measurements on a unique device platform, we study the reversible electrically-driven phase-change characteristics of self-assembled Ge₂Sb₂Te₅ nanowires. Detailed HRTEM analyses are used to correlate and understand the effect of full and intermediate structural transformations on the measured electrical properties of the nanowire devices. The study demonstrates that our unique approach has the potential to provide new information regarding the dynamic structural and electrical states of phase-change materials at the nanoscale, which will aid the design of future phase-change memory devices.