Use of Nanostructures for High Brightness Light-Emitting Diodes

Abstract

Light-emitting diodes or LEDs are expected to play a major role in efforts to utilize less energy for lighting applications due to their high efficiency, long operating life, and other "green" characteristics. The history of LEDs began in the 1960s. Since that time, the performance has increased exponentially while the cost has decreased dramatically. LEDs dominate the market for monochromatic displays and indicators, and are slated to provide an increasing share of the white light market. During the last decade, advances in efficiency have been obtained partly as a result of the use of nanotechnology. LEDs and lasers provided some of the first applications for quantum-well structures with nm dimensions. Future advances will almost certainly be linked to advances in the use of quantum wire and quantum dot structures. They appear to offer attractive new alternatives for single-junction white light generation. The use of self-assembled structures also offers the promise of allowing the fabrication of high efficiency devices in highly defected materials, such as those grown on less expensive substrates. This chapter reviews the basic aspects of LED devices and materials, with a focus on the AlGaInP system for red and yellow emitters and AlGaInN for blue, green, and white emitters, all grown by the organometallic vapor phase epitaxial technique. The focus is on the present and future use of nanotechnology for lighting applications.