The research focuses on surface plasmon resonance, where the interface between a conducting and an insulating material is illuminated. The team says that, if the angle, polarisation and wavelength of the incoming light are just right, electrons in the conductor begin oscillating. This creates an intense electric field extending into the insulator that can be used in everything from biomedical sensors to solar cells or optoelectronic devices.
However, the wavelength of light that causes these oscillations depends on the nature of the conductive material. "There are at least three practical reasons for wanting to identify materials that exhibit surface plasmon resonance in response to mid IR light," says Dr Jon-Paul Maria, a professor of materials science and engineering at NC State. "First, it could make solar harvesting technology more efficient by taking advantage of the mid-IR wavelengths of light; that light wouldn't be wasted. Second, it would allow us to develop more sophisticated molecular sensing technology for use in biomedical applications. And third, it would allow us to develop faster, more efficient opto-electronic devices."
Specifically, the research team has 'doped' cadmium oxide with dysprosium. This does two things: it creates free electrons in the material; and it increases the mobility of the electrons.
"Usually, when you dope a material, electron mobility goes down," Dr Maria says. "But, in this case, we found the opposite – more dysprosium doping increases this critical characteristic."
