Effects of Luminescence Efficiency in InGaN-GaN LEDs by Inserting a LT-GaN Underlying Layer to Separate Nonradiative Recombination Centers

We have investigated the effects of nonradiative recombination centers (NRCs) on the device performances of InGaN/GaN multi-quantum-well (MQW) light-emitting diodes (LEDs) incorporating low-temperature n-GaN (LT-GaN) underlying layers. Inserting an LT-GaN underlying layer prior to growing the MQWs is a successful means of separating the induced NRCs as a result of the presence of a growth interrupt interface between the n-GaN template and the InGaN QW. We found that inserting an LT-GaN underlying layer prior to growing the MQWs could improve the external quantum efficiency of as-grown conventional LEDs. In our best case, the external quantum efficiency of a blue LED incorporating a 70-nm-thick LT-GaN was 16% higher (at 20 mA) than that of the corresponding as-grown blue LED. Finally, it would also use in optical-fiber short-wavelength communication systems at particular condition.