Tunnel-junction light-emitting diodes

The use of p-n tunnel junctions for applications in GaN-based electronic and optoelectronic devices has become increasingly attractive. The use of tunnel junctions has conceptually been desired for the reuse of carriers for coupled active regions, enabling high quantum efficiencies and improved vertical transport (Ozden et al., 2001). Concepts of the tunnel field-effect transistors, multiple active region light-emitting diodes (LEDs) and laser diodes, high-conductivity hole injection layers, and multijunction solar cells may be realized with the III-nitride material system providing that a sufficiently low-resistivity tunnel junction can be obtained. However, the feasibility of forming low-resistivity tunnel junctions in the wide-bandgap III-nitride devices has been a challenge due to the high hole and electron concentrations required for band alignment. Substantial effort is still required to resolve this critical issue.