Using state-of-the-art theoretical methods, UCSB researchers have identified a specific type of defect in the atomic structure of a light-emitting diode (LED) that results in less efficient performance. The characterization of these point defects could result in the fabrication of even more efficient, longer lasting LED lighting.
“Techniques are available to assess whether such defects are present in the LED materials and they can be used to improve the quality of the material,” said materials professor Chris Van de Walle, whose research group carried out the work.
In the world of high-efficiency solid-state lighting, not all LEDs are alike. As the technology is utilized in a more diverse array of applications — including search and rescue, water purification and safety illumination, in addition to their many residential, industrial and decorative uses — reliability and efficiency are top priorities. Performance, in turn, is heavily reliant on the quality of the semiconductor material at the atomic level.
“In an LED, electrons are injected from one side, holes from the other,” explained Van de Walle. As they travel across the crystal lattice of the semiconductor — in this case gallium-nitride-based material — the meeting of electrons and holes (the absence of electrons) is what is responsible for the light that is emitted by the diode: As electron meets hole, it transitions to a lower state of energy, releasing a photon along the way.