Europium doping to create novel optical devices
While nitride semiconductors doped with Europium (Eu) show potential for the creation of novel optical devices, such as low threshold lasers and single photon emitters, not all the Eu ions are found in optically active sites. This means methods need to be developed to incorporate Eu ions selectively at optical sites.
Hiroto Sekiguchi and colleagues at Toyohashi University of Technology, in Tokyo, and Hamamatsu Photonics have improved the emission intensity from Eu ions by codoping with Mg. Demonstrating the potential, they have fabricated red leds which feature an active layer doped with Eu and Mg ions.
This codoping enhanced a specific emission site and contributed to a photoluminescence (PL) intensity increase of more than one order of magnitude. According to the research team, the ratio of PL integrated intensity at 25K to that at 300K was as high as 77%.
The team then fabricated Eu doped GaN based leds, which had a turn on voltage of 3.2V and a pure red emission observable by the naked eye at room temperature.
