Blue micro LEDs miniaturize displays.

• Position: Optics - Light-emitting diodes - Brief Article

Imagine being able to carry your computer in your pocket and view the screen through a pair of eyeglasses while listening to your quarter-sized CD. Imagine the military being able to detect the presence of biological chemicals in the air with the use of head-mounted microdisplays. These are just some of the potential future applications of light-emitting diodes, or LEDs.

A team of researchers from Kansas State University, Manhattan, led by Hongxing Jiang and Jingyu Lin, has created blue micro LEDs that are more efficient than conventional ones. Basically, putting hundreds of interconnected miniature LEDs in the same space one conventional LED used to take up could boost the efficiency by 60%. "We can make very small images," Lin indicates. "The diameter we've made of an LED is as small as a human hair."

Conventional LEDs are small lights used together to make up a variety of large lights and screens, including traffic signals, sports stadium screens, and neon billboards. A very energy-efficient light source, LEDs don't emit heat and have a long duration. By comparison, on average, a 15-watt stoplight can last, 20,000 hours, while a 100-watt house lightbulb lasts approximately 1,000.

"Most microdisplays, like cell phone screens, are made of liquid crystal or LCDs, which require an external light source," Lin explains. "What we've made is a miniature semiconductor display. Basically, they are self-luminescent, resulting in both space and power saving." Blue LEDs, however, are not available at this time in microsizes, he notes, making it virtually impossible to use in smaller items, such as heat-mounted microdisplays and cell phone displays.

Particular to the Kansas State University research is the creation of miniature blue LEDs, Jiang points...