University of California Santa Barbara have been goosing LEDs with new techniques to wring more light from them. UCSB electrical and computer engineering professor Jonathan Schuller works with Claude Weisbuch and Nobel laureate Shuji Nakamura on the new technology.
Usually LEDs emit spontaneous light, versus a laser’s stimulated, coherent light. The research team focused on metasurfaces—engineered surfaces with nanoscale features—that interact with light and manage and control the photons from the LED.
The design they arrived at consists of an array GaN nanorods, each 1.45 µm long, on a sapphire substrate. Quantum wells of InGaN are embedded in the nanorods to confine electrons and holes and thus emit light. In addition to allowing more light to leave the semiconductor structure, the design polarises the light. The work has been published in Nature Photonics.
With UC Santa Barbara’s SSLEEC (Solid State Lighting and Energy Electronics Center) and the campus’ nanofabrication facility, the researchers designed and patterned the semiconductor surface to adapt the metasurface concept for spontaneous light emission.