Carrier injection via V-defects for efficient green and red GaN LEDs

Abstract

Long wavelength InGaN/GaN quantum well (QW) light emitting diodes (LEDs) are essential components of solid-state lighting and displays. However, efficiency of these devices is inferior to that of blue LEDs. To a large degree, this occurs because equilibration of injected holes between multiple QWs of the active region is hindered by the high GaN quantum confinement and polarization barriers. This drawback could be overcome by lateral hole injection via semipolar QWs present on facets of V-defects that form at threading dislocations in polar GaN-based structures. In this work we have tested the viability of this injection mechanism and studied its properties by time-resolved and near-field spectroscopy techniques on multiple QW devices. We have found that indeed the hole injection via the V-defects does take place, the mechanism is fast, and the hole spread from the V-defect is substantial making this type of injection feasible for efficient long wavelength GaN LEDs.