Deep hole injection assisted by large V-shape pits in InGaN/GaN multiple-quantum-wells blue light-emitting diodes

We investigated the hole injection mechanism in InGaN/GaN blue light-emitting diodes by growing monolithic dual-wavelength multiple-quantum-wells and measuring the electroluminescence spectra at different current densities under room temperature. By analyzing the spectral competition from quantum wells at different vertical locations, the hole injection depth was quantitatively measured. During the epitaxial growth, large size V-shape pits with 200-330 nm diameter were intentionally formed in the active region by controlling the growth condition. It was found that such defect has a significant influence on the hole injection depth. With large V-shape pits and reduced quantum barrier thickness, the hole can be injected beyond 8 pairs of quantum well/quantum barrier. And less droop effect at large current density were observed. A carrier transport model with the presence of large V-shape pits is established. (C) 2014 AIP Publishing LLC.