A team of researchers at Sheffield University in the United Kingdom recently published the latest in LEDs in semiconductors using the Physics Physics Letters on semipolar GaN or sapphire substrates .
Using microcolumn array templates made of GaN grown on M-Plane sapphire substrates, researchers are able to grow LEDs with higher quantum efficiency on semipolar GaN (11-22) overgrowth.
The research team's green LEDs grown on semipolar materials show that the blue shift of the emission wavelength decreases as the drive current increases compared to commercial LEDs grown on C-Plane sapphire substrates. The observed shift in blue shift also applies to yellow-green and yellow LEDs, so the researchers found that there is an effect in the growth of LEDs that effectively suppresses quantum yield while limiting star-dazzle.
(A) green (b) yellow-green (c) yellow (d) at 5mA, 20mA and 100mA, respectively Amber LED electroluminescence
The researchers measured the light source output as a linear increase in current rise on the wafer while its external quantum efficiency showed a significant improvement over the efficiency-droop of a commercial C-Plane LED. Electroluminescence Polarization measurements show that the polarization ratio of semi-polar LEDs is about 25%.
The researchers claim preliminary results show that overgrowth technology is a more cost-effective way to achieve high-performance semipolar GaN emitters over longer wavelengths.
Water Based Inkjet Receptive Coating For Canvas
Water Based Inkjet Receptive Coating For Canvas,Inkjet Paper ,Polycarbonate Coating,Soft Touch Coating
Guangzhou Quanxu Technology Co Ltd , https://www.skysilmattingagent.com