Infrared LEDs can be made cheaper, compatible with silicon

Light-emitting diodes at infrared wavelengths are the magic behind such things as night vision and optical , including the streaming data that comes through Netflix. Cornell researchers have advanced the process of making such LEDs cheaper and easier to fabricate, which could lead to ultra-thin LEDs painted onto silicon to replace computer wiring with light waves. The research group led by Frank Wise, professor of applied and engineering physics, reported online May 6 Nanotechnology that they have used solution chemistry to make infrared LEDs out of nanocrystals, commonly known as quantum dots, out of lead sulfide. Their process, which involves tuning emitted wavelengths based on controlling the size of the nanocrystals, could rival the effective, but expensive, practice of growing semiconductor materials using the atom-by-atom process known as epitaxy. The Cornell nanocrystal LEDs are about as bright as epitaxially grown LEDs, but they were made using low-temperature, solution-based processing that is much cheaper. Infrared LEDs are usually made of crystals of such materials as indium gallium arsenide, and they cannot be grown on silicon due to their different crystal structures, Wise explained. Thus far there has been no natural way to make light-emitting materials on silicon.