High-efficiency near-UV light-emitting diodes on Si substrates with InGaN/GaN/AlGaN/GaN multiple quantum wells

Abstract

Both the weak carrier confinement in InGaN/GaN multiple quantum wells (MQWs) and the severe quantum-confined Stark effect in InGaN/AlGaN MQWs limit the improvement of quantum efficiency for near-ultraviolet (UV) light-emitting diodes (LEDs). In this regard, we have demonstrated high quantum efficiency LEDs grown on 4 inch Si substrates with well-designed InGaN/GaN/AlGaN/GaN MQWs. On the one hand, the proposed GaN interlayer barrier can increase the concentration and the spatial overlap of carriers in the MQWs for modulating the energy band and polarization theoretically. On the other hand, the GaN interlayer barrier grown by two-step temperature control can effectively improve the quality of the MQWs. The as-fabricated 395 nm near-UV LED chips with InGaN/GaN/AlGaN/GaN MQWs reveal an external quantum efficiency of 60% and a light output power of 659 mW at an injection current of 350 mA. This work provides a valuable solution to obtain high quantum efficiency and high power near-UV LEDs.