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 x >= 0.28 in the InxGa1-xN quantum well. The AlyGa(1-y)N interlayers (ILs) with high Al-content (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(1-z)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 similar to 100 times lower due to lower wavefunction overlap. A and C coefficients are higher because of a higher number of defects.