Recombination Rate Analysis of InGaN-Based Red-Emitting Light-Emitting Diodes

The recombination rates are measured and analyzed for red-emitting InGaN light-emitting diodes (LEDs) to better understand the factors that limit their efficiency. InGaN/AlGaN/GaN multiple quantum well (MQWs) are grown with $\text{x}\ge 0.28$ in the InxGa $_{\mathrm {1-x}}\text{N}$ quantum well. The AlyGa $_{\mathrm {1-y}}\text{N}$ interlayers (ILs) with high Al-content ( $\text{y}>$ 0.8) are employed because they result in smoother surfaces with smaller V-pits and higher photoluminescence efficiency. The IL-MQWs are formed on GaN and InzGa $_{\mathrm {1-z}}\text{N}$ /GaN superlattice (SL) underlayers (ULs) with $z =0.015$ , 0.025, and 0.065. Differences in $B$ coefficients (radiative recombination) within this set result from changes in wavefunction overlap caused by differences in layer thickness and composition in the IL-MQW. IL-MQWs grown on SL-ULs have $A$ coefficients (Shockley-Reed-Hall recombination) that are lower than expected, indicating that the SL-ULs help reduce defect formation. Compared to shorter wavelength InGaN-based LEDs, the $B$ coefficients are $\sim $ 100 times lower due to lower wavefunction overlap. A and $C$ coefficients are higher because of a higher number of defects.