Appl. Phys. Lett. 103, 191102 (2013)

Miniature metal-clad semiconductor pillars are very promising for realizing nanoscale lasers for use in chip-scale photonic integrated circuits. However, such nanolasers almost invariably have to be operated at cryogenic temperatures because of their high optical losses and low quality factors. Now, researchers in Taiwan have developed an ultraviolet (∼365 nm) aluminium-clad GaN nanorod laser that operates at room temperature with a low threshold power density of 5.2 mJ cm−2. They achieved this by incorporating an additional wet-chemical etching step with potassium hydroxide during the fabrication of the nanolaser. This step created nanorods with very smooth and vertically straight sidewalls that are truly perpendicular to the substrate. The alignment of the nanorods is especially important as finite-element simulations indicate that the quality factor of the lasers will drop by nearly a third when the sidewall angle is reduced from 90° to 89°. The high-quality-factor plasmon lasing modes were characterized by both experiments and simulations.