Realization of Highly Efficient InGaN Green LEDs with Sandwich-like Multiple Quantum Well Structure: Role of Enhanced Interwell Carrier Transport

The potential of multicolor semiconductor electroluminescence in solid-state lighting has been extensively pursued due to the energy-saving and smart-lighting as compared to conventional phosphor-converted white light sources. Here, we demonstrate a highly efficient 525 nm GaN-based green light-emitting diode (LED) with a sandwich-like multiple quantum well (MQW) structure grown on patterned Si(111) substrates. Performance enhancement can be achieved by adjusting the thicknesses of the three quantum barriers close to p-GaN in the interior of the sandwich MQW. Samples A, B, and C, with an optimized barrier thickness of 13, 10, and 8 nm, showed peak external quantum efficiency (EQE) values of 55.6%, 56.2%, and 49.0%, respectively. Under normal working conditions (350 mA, current density 35 A/cm2), the output power, EQE, forward voltage, and dominant wavelength of the sample representing the best performance were 306.0 mW, 37.0%, 2.76 V, and 525 nm, respectively. This work might provide an economically feasible way to realize volume-produce of highly efficient InGaN green LEDs on silicon substrates.