Gallium nitride (GaN) light emitting diodes, or commonly known as LEDs are usually grown on a layer of silicon – that abundant material that makes up 90+% of Earth’s crust. A team of Chinese researchers have improved their efficiency by transferring them onto a layer of copper.
The GaN crystals on the copper substrate were thus able to release some of their internal stresses generated at their inception on the semiconductor surface. This led to the efficiency increase through the minimization of the “quantum confined stark effect.” The measurable effect was the 122 percent more powerful light emitted by the device, without any sign of degradation of the light-emitting region.
Other sources of efficiency improvement are (quoting Eurekalert!): “the removal of the absorptive substrate; the insertion of a metal reflector between the LEDs’ structure and the copper submount; the elimination of electrode shading, which also reduces efficiency; and the rough surface of the exposed buffer layer, which improves crystal orientation on the substrate.”
Now, copper is not that abundant in nature and it may offset the benefits of operating LED lighting systems, even though the efficiency is so great. However, copper can be nevertheless recycled, thus making the energy efficiency gains worthwhile and the technology a viable one and could change the face of green electronics.
We’ll keep you posted.