【研究成果】2015年

研究成果82

Europium propels the GaN LED into the red
Y. Fujiwara　(Osaka Univerisity), W. Jadwisienczak, and F. Rahman (Ohio University)
Compound Semiconductors 21 (2015) review pp. 50-53

Historically, to realize red LED, band gap engineering employing crystal growth techniques, devices with built-in In-rich thin layer and nano-columns have been studied extensively. Alternative approach, Europium-doped GaN developed by Yasufumi Fuijiwara at Osaka University has excellent luminescence properties in the red spectral region, resulting from the specific optical properties of rare-earth elements. This includes a sharp, intense, temperature-independent emission peak associated with intra-4f shell transitions. The Osaka University team has used MOCVD to grow europium-doped GaN layers with high crystalline quality, and demonstrated low-voltage, current-injected red emission from p-type GaN/GaN:Eu/n-type GaN LEDs: emitting light at a forward voltage of just 3 V at 621 nm with output power increasing to 93 μW at 20 mA, an external quantum efficiency of 0.23 %. Doping of GaN with europium enables a red LED to join forces with blue and green cousins and form a monolithic, full-colour chip