First the researchers used simulation to design and study the properties of a photonic crystal based on AlGaN nanowires. Described in a paper titled “An electrically injected AlGaN nanowire defect-free photonic crystal ultraviolet laser” published in Optics Express, the AlGaN nanowire photonic crystal laser was grown on a sapphire substrate using a site-controlled selective area growth (SAG) process.
In selective area growth, the nanowire formation is directly controlled by the nanoscale apertures created on a substrate using a well-defined top-down process. AlGaN nanowire arrays with controlled size and spacing were selectively grown on GaN-on-sapphire template using plasma-assisted molecular beam epitaxy. They were fabricated into photonic crystal lasers using standard photolithography, e-beam lithography, dry etching and contact-metallization techniques. The researchers deposited Ni/Au and Ti/Au metal layers on the nanowire top surfaces and n-GaN template to serve as p-and n-metal contacts, respectively. Because the nanowire structures exhibit nearly identical size distribution, they limit optical scattering losses and do not require any particular mirroring structure.