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Posted: May 17, 2012
Novel approach allows to grow nanocomposites faster
(Nanowerk News) Joshua Zide, assistant professor of materials science and engineering at the University of Delaware, has spent nearly a decade engineering nanomaterials using a technique called molecular beam epitaxy (MBE).
In his research, Zide makes a class of materials called nanocomposites that consist of metallic nanoparticles within a semi-conductor. These nanocomposites can be used in electronic devices such as transistors or in energy conversion devices such as solar cells or thermoelectrics. Typically, these devices are made of semiconductors like silicon or gallium arsenide.
Joshua Zide (right), assistant professor of materials science and engineering, at work in the laboratory with Pernell Dongmo, a doctoral candidate in the College of Engineering.
While MBE produces nanoscale materials with exquisite control, the technique is slow and expensive. It also doesn't scale well for industrial applications and it isn't flexible in allowing the addition of new materials.
Zide will attempt to grow nanoscale materials in a new way through a 2012 Department of Energy Early Career Research grant from the Office of Basic Energy Sciences. One of only 68 individuals selected from a pool of nearly 850 applicants, the award will provide Zide $750,000 in research funding over five years.
Under the grant, Zide will explore the use of liquid phase epitaxy (LPE) to make nanocomposites for thermoelectrics, which are devices for generating electrical energy from heat. The work shows potential for transitioning these promising materials from the laboratory to the factory, allowing production of innovative electronic, optoelectronic and energy conversion devices.
"People have used LPE many times to make semiconductors. What we're doing is making the same kinds of nanocomposites using a hybrid approach that also employs inert gas condensation," he said.
The research team will first make the metal nanoparticles in the laboratory via inert gas condensation and then use the nanoparticles to grow materials by LPE. According to Zide, combining these two well-established, inexpensive techniques in a new way opens the door to making this class of materials in a commercially viable and scalable way.
"Instead of growing nanomaterials at one micron per hour, which is much slower than grass grows, LPE will enable us to grow nanomaterials at one micron per minute," Zide said.
"We think this could lead to a faster, better, cheaper way of making a class of nanocomposite materials with pretty exciting applications," he added.
Separating the production of the nanoparticles from the production of the film also increases the materials flexibility and enables it to be changed in ways not possible by MBE. In principle, Zide said the technique could also be applied to other materials systems, enabling researchers to combine more dissimilar materials in electronic nanocomposites.
During the project, he will collaborate and share equipment with materials science and engineering colleagues Ismat Shah, whose expertise lies in making nanoparticles via inert gas condensation, and Robert Opila, whose expertise lies in LPE.
Two graduate students will also participate in the project. One student will focus on creating the nanoparticles and the other will incorporate the nanoparticles into the films designed in Zide's laboratory and to study the materials' characterization and properties.
"This long-term funding will enable me to lead my research in an entirely new direction," Zide said.
About the award
The U.S. Department of Energy Early Career Research Program aims to strengthen the nation's scientific workforce. The five-year awards are designed to support exceptional researchers during their early career years, when many scientists do their most seminal work.
Now in its third year, the program also aims to providing incentives for scientists to focus on research areas important to the Department of Energy including advanced scientific computing research, biological and environmental research, basic energy sciences, fusion energy sciences, high-energy physics and nuclear physics.
About the professor
Joshua Zide joined UD in 2007 as an assistant professor in electrical engineering with a joint appointment in mechanical engineering. He joined the materials science and engineering faculty in 2009.
Zide earned his doctoral degree in materials from the University of California Santa Barbara in 2007 and his bachelor's degree with distinction in materials science and engineering from Stanford University in 2002.
Source: By Karen B. Roberts, University of Delaware
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