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 a semitransparent electrode and spatially uniform luminescence exhibiting an improved radiative efficiency. Also, the current confinement aperture for the lateral injection current in the LEDs was defined by mesa etching of a TJ structure and regrowth of the current blocking layer surrounding the TJ mesa. The very uniform light emission just through a buried TJ aperture confirms 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.