Cool white III-nitride light emitting diodes based on phosphor-free indium-rich InGaN nanostructures

Phosphor-free cool white emitting light emitting diodes (LEDs) have been fabricated using a dual stacked InGaN∕GaN multiple quantum wells (MQWs) comprising of a lower set of MQWs emitting yellow and an upper set of MQWs emitting blue. The lower set of MQWs incorporates indium-rich InGaN connected-dot nanostructures with a height of ∼1.0nm in the well. The well is first grown with an InGaN layer serving as the wetting layer, then treated with trimethylindium (TMIn) to initiate nanostructure growth of another InGaN layer to complete the well layer. This gives a broadened yellow emission peak. With the combination of emission from the upper blue emitting InGaN∕GaN MQWs subsequently grown, cool white light emission is achieved. The In-rich nanostructures formed during TMIn treatment enhance indium incorporation in InGaN well and also act as effective radiative recombination sites for carriers at the lower set of MQWs.