Recombination Rates of InxGa1-xN/AlyGa1-yN/GaN Multiple Quantum Wells Emitting From 640 to 565 nm

The recombination rates in an In(0.25)Ga(0.7)5N/Al0.48Ga0.52N/GaN multiple quantum well (MQW) structure are measured to identify the cause of low efficiencies in high In-content InGaN quantum wells. The MQWs emit from 640 to 565 nm and are grown using metal-organic chemical vapor deposition (MOCVD). The addition of AlGaN interlayers within the MQW provides strain balancing and suppresses defect formation in high In-content InGaN quantum wells. The rates are found by transforming the optically measured radiative efficiency, differential carrier lifetimes, and optical absorption. Both components of non-radiative recombination rates, Shockley-Read-Hall (SRH) and Auger recombination, are found to be similar to the values of blue-emitting InGaN MQWs. The low SRH recombination rate is attributed to the use of the AlGaN interlayer. The radiative recombination rate, however, is more than an order of magnitude lower compared to blue emitting (lower In-content) InGaN-based MQWs. While this large reduction in radiative rate can be attributed to differences in carrier overlap and transition energy, it may also include effects of variations in thickness and compositional inhomogeneities.

Automated summary

The study found that adding AlGaN interlayers in high In-content InGaN quantum wells can provide strain balancing and suppress defect formation, resulting in a lower radiative recombination rate. While the non-radiative recombination rates are similar to blue-emitting InGaN quantum wells, the radiative recombination rate is more than an order of magnitude lower compared to lower In-content InGaN quantum wells.