Phosphor-Free, Color-Tunable Monolithic InGaN Light-Emitting Diodes

We have demonstrated phosphor-free color-tunable monolithic GaN-based light-emitting diodes (LEDs) by inserting an ultrathin 1-nm-thick InGaN shallow quantum well (QW) between deep InGaN QWs and GaN barriers. Without using any phosphors, this monolithic LED chip can be tuned to realize wide-range multicolor emissions from red to yellow under different injection currents. In partical, when the injection current reaches an upper level above 100 mA, the LEDs will achieve white emission with a very high color rending index (CRI) of 85.6. This color-tunable characteristic is attributed to the carrier redistribution in the shallow/deep QWs and the energy band filling effect as well.