(Invited) Phosphor-Free III-Nitride Nanowire White Light Emitting Diodes: Challenges and Prospects

Abstract

Tremendous progress has been made in GaN-based nanowire light-emitting diodes (LEDs), which can exhibit drastically reduced dislocation densities and polarization fields, compared to the conventional quantum well devices. However, the performance of nanowire LEDs is limited due to the poor hole transport, the electron overflow, and the large surface nonradiative recombination. In this context, we have investigated the molecular beam epitaxial growth, fabrication and characterization of full-color InGaN/(Al)GaN dot-in-a-wire LEDs on Si substrates, wherein the emission characteristics are controlled by the dot properties in a single epitaxial step. With the use of p-type modulation doping, electron blocking layer (EBL), and core-shell heterostructures, we have further demonstrated superior performance phosphor-free white LEDs that can exhibit record high output power of ~ 5.2 mW and unprecedentedly high color rendering index (CRI) of > 95.