Washington: Researchers have now developed a new technique that reduces defects in light-emitting diodes (LEDs), thus making it more efficient.
LED lighting relies on the gallium nitride (GaN) thin films to create the diode structure that produces light. The new technique now reduces the number of defects in those films by two to three orders of magnitude.
“This improves the quality of the material that emits light,” said Salah Bedair at the North Carolina State University.
“So, for a given input of electrical power, the output of light can be increased by a factor of two — which is very big,” he added.
This is particularly true for low electrical power input and for LEDs emitting in the ultraviolet range.
Bedair, along with Nadia El-Masry, started with a GaN film that was two microns, or two millionths of a meter, thick and embedded half of that thickness with large voids — empty spaces that were one to two microns long and 0.25 microns in diameter.
They found that defects in the film were drawn to the voids and became trapped — leaving the portions of the film above the voids with far fewer defects.
By placing voids in the film, the researchers effectively placed a ‘surface’ in the middle of the material, preventing the defects from travelling through the rest of the film.
“Without voids, the GaN films have approximately 1010 defects per square centimetre,” said Bedair.
“With the voids, they have 107 defects. This technique would add an extra step to the manufacturing process for LEDs, but it would result in higher quality, more efficient LEDs,” he added.
The paper was published online January 17 by Applied Physics Letters.