Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > New analytical technology reveals 'nanomechanical' surface traits

A new research platform uses a laser to measure the "nanomechanical" properties of tiny structures undergoing stress and heating, an approach likely to yield insights to improve designs for microelectronics and batteries. Clockwise from upper left, graphics of the instrument setup, and at bottom right a scanning electron microscope image of the tiny silicon cantilever used in the research. Ming Gan/Purdue University photo
A new research platform uses a laser to measure the "nanomechanical" properties of tiny structures undergoing stress and heating, an approach likely to yield insights to improve designs for microelectronics and batteries. Clockwise from upper left, graphics of the instrument setup, and at bottom right a scanning electron microscope image of the tiny silicon cantilever used in the research.

Ming Gan/Purdue University photo

Abstract:
Surface stress variation as a function of applied compressive stress and temperature in microscale silicon

Ming Gan and Vikas Tomara

School of Aeronautics and Astronautics, Purdue University

Surface stress has been shown to affect the mechanical properties of materials at or below the microscale. Surface-stress-induced dislocation activity at such length scales has been shown to be a major factor affecting the mechanical behavior of materials. Defect generation as a function of applied stress at the microscale has previously been measured experimentally and predicted using simulations. However, the change in surface stress in a material in response to externally applied stress as a function of temperature has not been explored experimentally. Such an investigation is presented in this work for the case of microscale silicon samples. In-situ nondestructive measurements of the applied compressive stress and the corresponding microscale surface stress were performed from room temperature to 100 C. The applied stress was controlled by a nanomechanical loading system. Micro-Raman spectroscopy was used to measure the surface stress in-situ as the samples deformed under the applied uniaxial compressive stress. The surface stress was found to be lower than the applied stress at all temperatures. The difference between the surface stress and the applied stress became higher at higher temperatures indicating that surface relaxation was induced by the temperature increase. Based on the measured values and observed trends, an exponential Gaussian function is proposed to describe the stress as a function of surface depth. VC 2014 AIP Publishing LLC. [dx.doi.org/10.1063/1.4892623]

New analytical technology reveals 'nanomechanical' surface traits

West Lafayette, IN | Posted on August 29th, 2014

A new research platform uses a laser to measure the "nanomechanical" properties of tiny structures undergoing stress and heating, an approach likely to yield insights to improve designs for microelectronics and batteries.

This new technique, called nanomechanical Raman spectroscopy, reveals information about how heating and the surface stress of microscale structures affect their mechanical properties. Researchers have discussed the merits of surface-stress influence on mechanical properties for decades. However, the nanomechanical Raman spectroscopy has offered the first such measurement, said Vikas Tomar, an associate professor in Purdue's School of Aeronautics and Astronautics.

Surface stress is similar to the surface tension that allows small insects to walk on water, makes water drops spherical, and causes human skin to initially resist a needle's penetration. On the relatively large scale of ordinary, everyday machines, surface stress is negligible, but it becomes critical for micro- and nanostructures, he said.

Recent findings are potentially important because silicon structures measured on the scale of micrometers and nanometers form essential components of semiconductor processors, sensors and an emerging class of miniscule machines called microelectromechanical systems.

"The functioning of such devices has been found to be highly affected by their operating temperature," Tomar said. "Such densely packaged devices generate considerable heat during operation. However, until now we have not been able to measure how heating and surface stress contribute to mechanical properties."

Information about the platform and new research findings were detailed in three papers published this year. The most recent appeared Aug. 15 in the Journal of Applied Physics. Tomar has led the research with former doctoral student Ming Gan, who has graduated and is now working in industry, and current doctoral student Yang Zhang.

In Raman spectroscopy, a laser interacts with the vibrating crystal lattice of materials, providing information about the chemical makeup of the materials.

"But we have not been able to incorporate in-situ stress or deformation into those chemical signatures," Tomar said. "Now we have combined nanomechanical measurements into Raman spectroscopy."

The researchers used the technique to study microscale silicon cantilevers, tiny diving-board shaped slivers about 7 microns thick, or roughly one-tenth the thickness of a human hair, and 225 microns long. The cantilevers were heated and stressed simultaneously. Surface stresses at the micro- and nanoscales were measured for the first time in conjunction with temperature change and a structure's deformation.

Findings show that heating a cantilever from 25 to 100 degrees Celsius while applying stress to the structure causes a dramatic increase in strain rate, or deformation.

The heating reduces bonding forces between atoms on the surface of the structures. The lower bonding force results in a "relaxed" state of the surface or near-surface atoms that progresses as the temperature increases, leading to cracks and device failure.

"The key is to be able to measure thermal and mechanical properties simultaneously because they are interrelated, and surface stress influences mechanical properties," Tomar said.

Findings are potentially important for the measurement of components in batteries to study stresses as they constantly expand and contract during charge-discharge cycles. Ordinary sensors are unable to withstand punishing conditions inside batteries.

However, because Raman spectroscopy uses a laser to conduct measurements, it does not have to be attached to the batteries, making possible a new type of sensor removed from the harsh conditions inside batteries.

"If you don't need onboard sensors you can go into extreme environments," he said. "You can learn how the stresses are evolving so that we can design better batteries."

Such a technology also could be important for development of super-strong composite materials that mimic those found in some marine animals that are able to survive in the extreme conditions found in ocean-floor hydrothermal vents. One obstacle is overcoming stresses that occur at the interfaces of different layers within the composite materials.

"These materials always break at the interfaces," Tomar said. "Now we can understand as the material is deforming how the interface stresses are developing, and this will allow us to predict how to modify them."

Purdue has filed a provisional patent for the new platform. The research has been funded by the National Science Foundation.

####

For more information, please click here

Contacts:
Writer:
Emil Venere
765-494-4709


Sources:
Vikas Tomar
765-494-3423

Copyright © Purdue University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

Download article:

Related News Press

Imaging

Columbia Researchers Squeeze Light into Nanoscale Devices and Circuits: Team is first to directly image propagation and dynamics of graphene plasmons at very low temperatures; findings could impact optical communications and signal processing May 23rd, 2018

NIST Puts the Optical Microscope Under the Microscope to Achieve Atomic Accuracy May 22nd, 2018

News and information

Columbia Researchers Squeeze Light into Nanoscale Devices and Circuits: Team is first to directly image propagation and dynamics of graphene plasmons at very low temperatures; findings could impact optical communications and signal processing May 23rd, 2018

NIST Puts the Optical Microscope Under the Microscope to Achieve Atomic Accuracy May 22nd, 2018

Magnesium magnificent for plasmonic applications: Rice University, University of Cambridge synthesize and test nanoparticles of abundant material May 22nd, 2018

Govt.-Legislation/Regulation/Funding/Policy

Columbia Researchers Squeeze Light into Nanoscale Devices and Circuits: Team is first to directly image propagation and dynamics of graphene plasmons at very low temperatures; findings could impact optical communications and signal processing May 23rd, 2018

NIST Puts the Optical Microscope Under the Microscope to Achieve Atomic Accuracy May 22nd, 2018

Magnesium magnificent for plasmonic applications: Rice University, University of Cambridge synthesize and test nanoparticles of abundant material May 22nd, 2018

Self-assembling 3D battery would charge in seconds May 22nd, 2018

Chip Technology

Columbia Researchers Squeeze Light into Nanoscale Devices and Circuits: Team is first to directly image propagation and dynamics of graphene plasmons at very low temperatures; findings could impact optical communications and signal processing May 23rd, 2018

Supersonic waves may help electronics beat the heat May 18th, 2018

Deeper understanding of quantum chaos may be the key to quantum computers May 16th, 2018

Strain improves performance of atomically thin semiconductor material May 11th, 2018

Announcements

Columbia Researchers Squeeze Light into Nanoscale Devices and Circuits: Team is first to directly image propagation and dynamics of graphene plasmons at very low temperatures; findings could impact optical communications and signal processing May 23rd, 2018

NIST Puts the Optical Microscope Under the Microscope to Achieve Atomic Accuracy May 22nd, 2018

Magnesium magnificent for plasmonic applications: Rice University, University of Cambridge synthesize and test nanoparticles of abundant material May 22nd, 2018

Self-assembling 3D battery would charge in seconds May 22nd, 2018

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers

Columbia Researchers Squeeze Light into Nanoscale Devices and Circuits: Team is first to directly image propagation and dynamics of graphene plasmons at very low temperatures; findings could impact optical communications and signal processing May 23rd, 2018

NIST Puts the Optical Microscope Under the Microscope to Achieve Atomic Accuracy May 22nd, 2018

Magnesium magnificent for plasmonic applications: Rice University, University of Cambridge synthesize and test nanoparticles of abundant material May 22nd, 2018

Self-assembling 3D battery would charge in seconds May 22nd, 2018

Tools

Columbia Researchers Squeeze Light into Nanoscale Devices and Circuits: Team is first to directly image propagation and dynamics of graphene plasmons at very low temperatures; findings could impact optical communications and signal processing May 23rd, 2018

NIST Puts the Optical Microscope Under the Microscope to Achieve Atomic Accuracy May 22nd, 2018

Self-assembling 3D battery would charge in seconds May 22nd, 2018

A micro-thermometer to record tiny temperature changes May 15th, 2018

Patents/IP/Tech Transfer/Licensing

Self-assembling 3D battery would charge in seconds May 22nd, 2018

Leti Silicon Photonics Design Kit Available in Synopsis OptoDesigner Suite: Kit Contains Design Rules and Building Blocks for Multi-Project Wafers And Custom Runs on Letiís Si310 Platform April 5th, 2018

NTU scientists create customizable, fabric-like power source for wearable electronics January 30th, 2018

IBM Breaks Records to Top U.S. Patent List for 25th Consecutive Year: IBM Inventors Receive Record 9,043 Patents in 2017 in Areas such as Artificial Intelligence, Cloud, Blockchain, Cybersecurity and Quantum Computing January 11th, 2018

Battery Technology/Capacitors/Generators/Piezoelectrics/Thermoelectrics/Energy storage

Self-assembling 3D battery would charge in seconds May 22nd, 2018

Mining for gold with a computer: Texas A&M team gleans new insights on key material May 3rd, 2018

The dispute about the origins of terahertz photoresponse in graphene results in a draw April 26th, 2018

Ultra-powerful batteries made safer, more efficient: Team aims to curb formation of harmful crystal-like masses in lithium metal batteries April 12th, 2018

Photonics/Optics/Lasers

Columbia Researchers Squeeze Light into Nanoscale Devices and Circuits: Team is first to directly image propagation and dynamics of graphene plasmons at very low temperatures; findings could impact optical communications and signal processing May 23rd, 2018

A micro-thermometer to record tiny temperature changes May 15th, 2018

Strain improves performance of atomically thin semiconductor material May 11th, 2018

A powerful laser breakthrough: Lehigh research team demonstrates terahertz semiconductor laser with record-high output power May 2nd, 2018

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project