Future of group-III nitride semiconductor green laser diodes [Invited]

Some research groups have realized green laser diodes (LDs) using InGaN-based nitride semiconductors. However, the performances of their devices, in particular wall-plug efficiency, were still one digit lower than those of established red and blue semiconductor LDs. To achieve high-performance green LDs and apply them to LD displays or micro-projectors, the field should focus on improving the internal quantum efficiency (IQE) of green spontaneous emission from InGaN quantum wells (QWs). Green InGaN QWs have completely different features than blue InGaN QWs in terms of growth and concomitant material quality. The exploration of 100% IQE-quality InGaN materials for green emission continues.