Featured Research

from universities, journals, and other organizations

New Nanofabrication Technique: Growing Nanostructures On Micro Cantilever Provides New Platform For Materials Discovery

Date:
June 7, 2006
Source:
Georgia Institute of Technology
Summary:
Researchers have developed a new technique that could provide detailed information about the growth of carbon nanotubes and other nanometer-scale structures as they are being produced. The technique offers a way for researchers to rapidly and systematically map how changes in growth conditions affect the fabrication of nanometer-scale structures.

Scanning electron microscope image showing carbon nanotubes growing on the heated portion of an atomic force microscope cantilever.
Credit: Image courtesy Erik O. Sunden

Researchers have developed a new technique that could provide detailed information about the growth of carbon nanotubes and other nanometer-scale structures as they are being produced. The technique offers a way for researchers to rapidly and systematically map how changes in growth conditions affect the fabrication of nanometer-scale structures.

Instead of a large furnace that is normally used to grow nanotubes as part of the chemical vapor deposition process, the Georgia Institute of Technology researchers grew bundles of nanotubes on a micro-heater built into an atomic force microscope (AFM) tip. The tiny device provided highly-localized heating for only the locations where researchers wanted to grow the nanostructures.

Because the resonance frequency of the cantilever changed as the nanotubes grew, the researchers were able to use it to accurately measure the mass of the structures they produced. The next step in the research will be to combine the growth and measurement processes to permit in situ study of mass change during nanostructure growth.

"There are hundreds of materials â�" electronic, magnetic and optical â�" that are grown using a similar thermally-based technique," said William P. King, an assistant professor in Georgia Tech's School of Mechanical Engineering. "By growing these structures on cantilevers, we will be able to determine exactly what is happening with the materials growth as it occurs. This could provide a new tool for investigating the growth of these structures under different conditions."

Using arrays of cantilevers operating at different temperatures would allow researchers to accelerate the process for mapping the kinetics of nanostructure growth. Because the cantilevers can be heated and cooled more rapidly than a traditional furnace, batches of nanostructures can be produced in just 10 minutes â�" compared to two hours or more for traditional processing.

"We can change the structures being grown by rapidly changing the temperature," explained Samuel Graham, also an assistant professor in Georgia Tech's School of Mechanical Engineering. "We can also change the kinetics of growth, which is something that is difficult to do using conventional technology."

By demonstrating that carbon nanotubes can be growth on an AFM cantilever, the technique also provides a new way to integrate nanometer-scale structures with microdevices.

The research was supported in part by the National Science Foundation's CAREER award, and has been reported in the journal Applied Physics Letters.

King, Graham and collaborators Erik O. Sunden, Jungchul Lee and Tanya L. Wright began with an AFM cantilever fabricated in their Georgia Tech lab. The cantilever had an integrated electric-resistance heater whose output temperature could be controlled by varying the current. Actual heater temperatures were measured to within four degrees Celsius using Laser Raman thermometry.

Calibration of the cantilevers over a large temperature range using Raman spectroscopy was a key aspect of the success of this research, allowing the first detailed temperature maps of these devices, Graham noted.

The researchers used electron beam evaporation to deposit a 10 nanometer iron catalyst film onto the cantilever. After heating, the iron film formed islands that provided catalytic sites for growing nanotubes.

The cantilever was then placed into a quartz tube, which was purged of contaminants with argon gas. The cantilever heating was then turned on and the temperature held at approximately 800 degrees Celsius for 15 minutes. A combination of methane, hydrogen and acetylene â�" precursors for carbon nanotubes â�" was then flowed into the chamber. Only the cantilever tip and the reaction gas immediately around it were heated, leaving the remainder of the experimental set-up at room temperature.

After removal from the tube, the cantilever was examined using a scanning electron microscope, which showed vertically aligned carbon nanotubes growing from the cantilever heater region. The nanotubes ranged in length from five to 10 microns, and were 10 to 30 nanometers in diameter. Although the entire cantilever was coated with the iron catalyst, the nanotubes grew only on the heated area. A temperature gradient on the heater created differences in the types of nanotubes grown.

Both before and after the growth, the cantilever was vibrated so its resonance frequency could be measured. Those measurements showed a frequency decline from 119.10 to 118.23 kHz after the nanotubes were grown on the cantilever. After the resonance measurements were made, the cantilever was heated beyond 900 degrees Celsius in air to burn off the nanotubes. When the resonance frequency was measured again, it had changed to 119.09 kHz, showing that the frequency drop had been due to the mass of the nanotubes.

From the change in the resonance frequency, the researchers were able to calculate the mass of the carbon nanotubes they had grown as approximately four picograms (4 x 10-14) kg.

"We are working on integrating the growing and weighing of the nanotubes so we can do both of them at the same time," said King. "That would allow us to monitor the materials growth as it happens."

Once the two processes are integrated, the researchers expect to increase the number of cantilevers operating simultaneously. Cantilever arrays could allow many different growth temperatures and conditions to be measured in parallel, accelerating the task of charting the growth kinetics to determine the optimal settings.

"This is a platform for materials discovery, so we could test tens or even thousands of different chemistry or growth conditions in a very short period of time," King said. "With a thousand cantilevers, we could do in a single day experiments that would take years using conventional growth techniques. Once the right conditions were found, the production process could be scaled up."


Story Source:

The above story is based on materials provided by Georgia Institute of Technology. Note: Materials may be edited for content and length.


Cite This Page:

Georgia Institute of Technology. "New Nanofabrication Technique: Growing Nanostructures On Micro Cantilever Provides New Platform For Materials Discovery." ScienceDaily. ScienceDaily, 7 June 2006. <www.sciencedaily.com/releases/2006/06/060607081451.htm>.
Georgia Institute of Technology. (2006, June 7). New Nanofabrication Technique: Growing Nanostructures On Micro Cantilever Provides New Platform For Materials Discovery. ScienceDaily. Retrieved September 22, 2014 from www.sciencedaily.com/releases/2006/06/060607081451.htm
Georgia Institute of Technology. "New Nanofabrication Technique: Growing Nanostructures On Micro Cantilever Provides New Platform For Materials Discovery." ScienceDaily. www.sciencedaily.com/releases/2006/06/060607081451.htm (accessed September 22, 2014).

Share This



More Matter & Energy News

Monday, September 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Thousands March in NYC Over Climate Change

Thousands March in NYC Over Climate Change

AP (Sep. 21, 2014) — Accompanied by drumbeats, wearing costumes and carrying signs, thousands of demonstrators filled the streets of Manhattan and other cities around the world on Sunday to urge policy makers to take action on climate change. (Sept. 21) Video provided by AP
Powered by NewsLook.com
What This MIT Sensor Could Mean For The Future Of Robotics

What This MIT Sensor Could Mean For The Future Of Robotics

Newsy (Sep. 20, 2014) — MIT researchers developed a light-based sensor that gives robots 100 times the sensitivity of a human finger, allowing for "unprecedented dexterity." Video provided by Newsy
Powered by NewsLook.com
MIT BioSuit A New Take On Traditional Spacesuits

MIT BioSuit A New Take On Traditional Spacesuits

Newsy (Sep. 19, 2014) — The MIT BioSuit could be an alternative to big, bulky traditional spacesuits, but the concept needs some work. Video provided by Newsy
Powered by NewsLook.com
New Music With Recycled Instruments at Colombia Fest

New Music With Recycled Instruments at Colombia Fest

AFP (Sep. 19, 2014) — Jars, bottles, caps and even a pizza box, recovered from the trash, were the elements used by four musical groups at the "RSFEST2014 Sonorities Recycling Festival", in Colombian city of Cali. Duration: 00:49 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins