Gold layer improves light sensor performance

Researchers in Singapore have found a way to boost the performance of molybdenum disulphide photodetectors with gold nanoparticles, a development that could improve a range of light-sensing technologies.

Molybdenum disulphide (MoS2) has semiconducting properties that make it a promising alternative to silicon in electronic devices. It also strongly absorbs visible light, leading to its employment in photodetectors used environmental sensing, process control, and optical communication devices.

Wei Chen, an assistant professor of chemistry and physics, along with graduate student Jia Dan Lin, and their colleagues at the National University of Singapore, applied a single, loosely arranged layer of gold nanoparticles to the top of a MoS2 photodetector.

The gold layer, less than 15 billionths of a metre 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, claimed Chen.

‘We anticipate orders of magnitude higher improvement of MoS2’s sensitivity using a higher density of coated nanoparticles,’ Chen said in a statement.

Chen believes 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 said.

The researchers have published their findings in Applied Physics Letters, The paper, Plasmonic enhancement of photocurrent in MoS2 field-effect-transistor colors, was authored by Jiadan Lin, Hai Li, Hua Zhang and Wei Chen.