University of Maryland’s Center for Nanophysics and Advanced Materials research team has developed a new type of sensitive detector of infrared light called hot electron bolometer that is effective for extensive applications.
Directed by Jun Yan, Research Associate and Professors Dennis Drew and Michael Fuhrer, researchers at UMD, developed the bolometer with the help of bilayer graphene. Based on the significant properties of graphene, the bolometer will be highly sensitive to a variety of light energies such as infrared, visible light, terahertz frequencies or submillimeter waves.
The findings of Maryland team have been published in Nature Nanotechnology dated June 3.
Semiconductors form the basis for a majority of photon detectors. The electrons in semiconductors never enter a "band gap". They absorb photons of light with higher energies than that of the band gap. The photovoltaic cells are based on this property.
Graphene possesses a bandgap of exactly zero energy, and is capable of absorbing photons of any energy. It is ideal for absorption of very low energy photons such as terahertz and infrared which pass through several semiconductors. It also acts as a photon absorber and has low electrical resistance. Based on these properties, researchers at UMD developed the hot electron bolometer. While absorbing light, electrons get heated and the change in the resistance is measured by this novel device.
The researchers resolved that upon operation at 5 K, bilayer graphene hot electron bolometer were faster and more sensitive than existing bolometers operating at equivalent temperatures. The graphene bolometer’s efficiency was extrapolated to lower temperature and achieved promising results.
However, the bilayer graphene bolometer has limited usage at high frequencies. Furthermore, it absorbs only a few percent of incident light. The research team will make effort to solve these complexities and is positive that graphene will be an effective photo-detecting material.
Source: http://www.umd.edu/