An attractive material system for nanowire applications is the group-III nitride semiconductor family, which can be tailored to emit, absorb or transmit light from the UV to the infrared. A vapour–liquid–solid deposition process was developed to grow AlGaN (p-type shell) / GaN (n-type core) nanowires on a Si substrate. The AlGaN sheath enhances the confinement of the optical mode and electrically confines carriers in the GaN quantum wire.

Compared to gold and copper, silver has the lowest absorption and produces the strongest plasmon resonances, particularly in the ultraviolet. Simulations of nanoscale emission and plasmonic-enhanced transfer of emission energy directed the design of the nanowire and metallic coating. This motivated the development of a solvothermal chemistry to deposit a dense packing of silver nanospheres. This nanostructured coating significantly enhanced the plasmonic-based transfer of electromagnetic energy generated in the nanowire to the external near-field.

This overall approach allows direct placement of single or multiple nanowires that can directly couple to a trench dielectric waveguide or metal plasmonic waveguide. Additionally, the NRL team is developing group III-nitride nanowire electronic transistors coupled to these plasmonically enhanced nanowire emitters.