Study on internal quantum efficiency of blue InGaN multiple-quantum-well with an InGaN underneath layer

Blue InGaN multiple-quantum-well (MQW) samples with different InxGa1-xN (x=0.01-0.04) underneath layers (ULs) were grown by metal organic vapor phase epitaxy (MOVPE). Temperature dependent photoluminescence showed that the InGaN UL can improve the internal quantum efficiency (IQE) of MQW effectively due to strain release. And a maximum IQE of 50% was obtained when the thickness and In content of the InGaN UL were 60 nm and 0.01, respectively. Furthermore, the larger In content or thickness of the InGaN UL makes the IQE lower. Arrhenius fit to the experiment data showed that the IQE fall was mainly caused by the quantity increase of the nonradiative recombination centers, which was believed related to the accumulated stress in InGaN ULs.