By blending their expertise, two materials science engineers at Washington University in St. Louis changed the electronic properties of a new class of materials — just by exposing it to light.
With funding from the Washington University International Center for Advanced Renewable Energy and Sustainability (I-CARES), Parag Banerjee, PhD, and Srikanth Singamaneni, PhD, both assistant professors of materials science, brought together their respective areas of research.
Singamaneni’s area of expertise is in making tiny, pebble-like nanoparticles, particularly gold nanorods. Banerjee’s area of expertise is making thin films. They wanted to see how the properties of both materials would change when combined.
The research was published online in August in ACS Applied Materials & Interfaces
The research team took the gold nanorods and put a very thin blanket of zinc oxide, a common ingredient in sunscreen, on top to create a composite. When they turned on light, they noticed that the composite had changed from one with metallic properties into a semiconductor, a material that partly conducts current. Semiconductors are commonly made of silicon and are used in computers and nearly all electronic devices.
“We call it metal-to-semiconductor switching,” Banerjee said. “This is a very exciting result because it can lead to opportunities in different kinds of sensors and devices.”
Banjeree said when the metallic gold nanorods are exposed to light, the electrons inside the gold get excited and enter the zinc oxide film, which is a semiconductor. When the zinc oxide gets these new electrons, it starts to conduct electricity.
“We found out that the thinner the film, the better the response,” he said. “The thicker the film, the response goes away. How thin? About 10 nanometers, or a 10 billionth of a meter.”
Other researchers working with solar cells or photovoltaic devices have noticed an improvement in performance when these two materials are combined; however, until now, none have broken it down to discover how it happens, Banerjee said.
“If we start understanding the mechanism for charge conduction, we can start thinking about applications,” he said. “We think there are opportunities to make very sensitive sensors, such as an electronic eye. We are now looking to see if there is a different response when we shine a red, blue or green light on this material.”
The Latest on: Metal-to-semiconductor switching
CrossRef Cited By Search Results
on April 14, 2017 at 11:41 am
This article [doi:10.1038/nnano.2011.123] has been cited in the following papers, taken from those publishers and societies that are participating in CrossRef's Cited-by Linking service. The number of citations from this service is usually lower than ... […]
Carbyne morphs when stretched: Calculations show carbon-atom chain would go metal to semiconductor
on July 21, 2014 at 9:06 am
In their previous work on carbyne, the researchers believed they saw hints of the transition, but they had to dig deeper to find that stretching would effectively turn the material into a switch. Carbyne chains of carbon atoms can be either metallic or ... […]
Scientists demo light-controlled semiconductor
on September 8, 2013 at 3:58 pm
In the university's release, one of the researchers, Parag Banerjee says the “metal-to-semiconductor switching” would be useful in a variety of sensors and other devices. The mechanism that powers the transition is the excitation of electrons in the ... […]
Shining a little light changes metal into semiconductor
on September 5, 2013 at 5:00 pm
Semiconductors are commonly made of silicon and are used in computers and nearly all electronic devices. "We call it metal-to-semiconductor switching," Banerjee says. "This is a very exciting result because it can lead to opportunities in different kinds ... […]
CrossRef Cited By Search Results
on March 2, 2013 at 4:35 pm
This article [doi:10.1038/nnano.2006.52] has been cited in the following papers, taken from those publishers and societies that are participating in CrossRef's Cited-by Linking service. The number of citations from this service is usually lower than ... […]
via Google News and Bing News