In-Hwan Lee received his Ph.D. degree in materials science and engineering from Korea University, Korea in 1997. During 1997-1999, he was a postdoctoral fellow at Northwestern University. Then, he joined Samsung Advanced Institute of Technology, where he led an epitaxial team and developed InGaN/GaN violet LDs. From 2002 to 2017, he was a faculty member at School of Advanced Materials Engineering, Chonbuk National University, Korea. With the sabbatical grant from LG foundation, he was at Yale University during 2008-2009. In 2017 March, he joined Department of Materials Engineering, Korea University, Korea as a full professor. His current research focuses on the development of nanotechnology-inspired novel optoelectronic devices including LEDs, displays (using micro/nano LEDs), photovoltaic devices, sensors, and photocatalysts (for water splitting and CO2 reduction). He has authored or coauthored over 300 peer-reviewed research articles in major scientific journals, and presented over 70 invited seminars and talks around the world, and holds over 20 patents at various stages of the process.
Micro and Nanorod LEDs for Display Applications
Micro- and nanorod light-emitting diode (LED) technology is expected to be used in next-generation displays. The opportunities to integrate micro- and nanorod LEDs with electronics, and into large-scale arrays, allow pixel addressable scalable integrated displays. The implications of reduced LED size in necessitating mitigation strategies for nonradiative device edge damage as well as the potential for higher drive current densities are discussed. This short course categorizes, reviews, and analyzes the main challenges and technical solutions in the manufacturing process of micro- and nanorod LED displays, covering epitaxial growth, wafer fabrication, mass transfer, chip-to-panel bonding related issues. In particular, technological challenges including full-color operation, reduced external quantum efficiency, low-yield mass transfer, and structure and process design will also be discussed from the system point of view. In the epitaxial growth section, the requirements, problems, and technical developments of epitaxial growth, especially the growth of AlInGaN red LED, will be reviewed. The LED chip characterization and fabrication section present the reasons for the low quantum efficiency and the methods to overcome this problem. This section also includes the unique characteristics of localized surface plasmon coupling effects, compared with those of traditional LEDs. Various mass transfer technologies are summarized in the mass transfer section. Promises and hurdles for large area displays such as TV and cinema display, and ultra small micro-display for AR (augmented reality) glasses will be addressed.