Jul 26, 2013 |
Gold nanoparticles improve photodetector performance
|
(Nanowerk News) The mineral molybdenum disulfide (MoS2), which, when solid, behaves in many ways like grease, has semiconducting properties that make it a promising alternative to silicon or graphene in electronic devices. It also strongly absorbs visible light, and so it has been widely employed in light-sensing photodetectors, which are used in a wide range of technologies, such as environmental sensing, process control in factories, and optical communication devices.
|
Researchers at the National University of Singapore have now found a way to boost the performance of MoS2 photodetectors even further -- with nanoparticles of gold. They describe this improvement in the journal Applied Physics Letters ("Plasmonic enhancement of photocurrent in MoS2 field-effect-transistor").
|
Wei Chen, an assistant professor of chemistry and physics, along with graduate student Jia Dan Lin, and their colleagues, applied a single, loosely arranged layer of gold nanoparticles to the top of a MoS2 photodetector. The gold layer, although less than 15 billionths of a meter thick (representing the diameter of each individual nanoparticle) and made up of fewer than 1000 individual particles, improved the photodetectors’ efficiency by a factor of three, according to Chen.
|
"We anticipate orders of magnitude higher improvement of MoS2’s sensitivity using a higher density of coated nanoparticles," Chen said.
|
Chen suspects that the plasmon oscillations (variations in the electron density) of individual nanoparticles -- which enhance the local optical field -- may be one reason for the improved performance of the photodetectors.
|
"The next step will focus on varying the materials used to make the nanoparticles, as well as their size, shape, and arrangement," Chen noted -- adjustments that will "tune" the plasmon resonance wavelength of the metal nanostructure arrays, making it possible for MoS2 photodetectors todetect multiple colors for the first time.
|