GaN-based light-emitting diodes using tunnel junctions

We demonstrate GaN-based light-emitting diodes (LEDs) with tunnel junction (TJ) structure and surface-emitting light-emitting diodes with TJ current aperture for lateral current confinement. The p⁺/n⁺ GaN TJs are located in the upper cladding layers of conventional devices, allowing n-type GaN instead of p-type GaN as a top contact layer. The reverse-biased tunnel contact junction provides lateral current spreading without semitransparent electrode and spatially uniform luminescence exhibiting an improved radiative efficiency. Also, the current confinement aperture for lateral injection current in the LEDs was defined by mesa etch of a TJ structure and regrowth of current blocking layer surrounding the TJ mesa. The very uniform light emission just through a buried TJ aperture represents that the buried TJ structure acts very effectively as a confinement aperture of lateral current injection, particularly in GaN-based vertical-cavity surface-emitting lasers.