Machine Design

LEDs of many colors

Researchers at Los Alamos National Laboratory have developed the first completely inorganic multicolor LEDs based on colloidal quantum dots in a gallium-nitride semiconductor.

This solid-state hybrid LED promises to lower energy usage and perform more reliably than other color LEDs. Until now, it has been difficult to make direct electrical connections to quantum dots, also known as nanocrystals. The Los Alamos team sidestepped the problem by embedding the dots between GaN injection layers using a technique called Enable. That stands for energetic neutron atom beam lithography/epitaxy. It let the team place dots in the semiconducting GaN without damaging their luminescence properties. By encapsulating a quantum dot a layer or two layers with dots of different sizes, the LED could emit a single color or two different ones, an important step toward building a device that generates white light.

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