A research paper on LED published by Professor Lee, Dong Seon’s team at School of Information and Communications, Gwangju Institute of Science and Technology (GIST‧President, Young Joon Kim) was named one of the ‘Highlights of 2012’ by SCI-indexed journal ‘Nanotechnology’.

   Professor Lee, Dong Seon’s team published ‘Au nanoparticle-decorated graphene electrodes for GaN-based optoelectronic devices’ in the journal ‘Nanotechnology’ last May which was named as one of the seven ‘Highlights of 2012’ in the Electronics and Photonics category, announced GIST on 18^th.

   Co-authored by Professor Lee, Dong Seon (corresponding author), Ph.D. student Shim, Jae Phil (first author · GIST School of Information and Communications), Professor Park, Seong Ju (GIST School of Information and Communications), and Professor Lee, Takhee (Seoul National University), the research paper received a record 700 downloads on the ‘Nanotechnology’ homepage, drawing the attention of researchers in the related fields.

   Previous research

Currently, indium tin oxide (ITO) films are most commonly used as a current spreading layer (transparent electrode layer) for GaN-based LEDs.

However, due to ITO’s several disadvantages such as change in transmittance by wavelength, lack of flexibility, and depletion of indium, there have been numerous studies to identify alternative solutions for a current spreading layer.

Graphene which is highly regarded as a new current spreading layer has its limitations to become a stable current spreading layer for LEDs due to uneven current spreading, high contact resistance on GaN and flammability in high current conditions.

   Pushing the limits

Research findings of Professor Lee’s team are considered a breakthrough achievement that can address these issues highlighted in prior research. Professor Lee’s team coated the surface of graphene with a thin layer of metal (silver·Ag 10nm) to create a Ag nanoparticle, enhancing the conductivity of graphene, allowing effective current spreading and the fabrication of a stable device.

Also, the team introduced a new technology where nanoparticles are selectively formed in limited areas on the surface of graphene and applied it to a current spreading layer for GaN-based LEDs. As a result, they were able to boost the efficiency in light extraction and achieve stability.