Carrier injection modulated by V-defects in InGaN/GaN multiple-quantum-well blue LEDs

We investigated the carrier injection mechanism in InGaN/GaN blue light-emitting diodes by growing monolithic dual-wavelength multiple quantum wells and measuring electroluminescence spectra at different current densities at room temperature. During the epitaxial growth, V-defects of different sizes were intentionally formed in the active region area by controlling the growth conditions. We found that the size of the V-defects has a significant effect on the spectral competition of dual-wavelength emissions. With small V-defects, light emitted from quantum wells near p-GaN is dominant. In a sample with large V-defects, quantum wells near n-GaN contribute more to carrier recombination. The hole injection depth of eight pairs of quantum wells far from p-GaN is quantitatively estimated. We attribute the different behaviors to the modulation of carrier injection depth by the formed V-defects.