Cleaved Mirrors for Nitride Semiconductor Lasers

We demonstrate smooth cleaved gallium nitride facet mirrors on Si(111) substrates fabricated by a microcleaving technology. Cantilever features were defined by photolithography, followed by a vertical photo-enhanced electrochemical (PEC) etch until the substrate was exposed. Lateral undercuts underneath the cantilevers were created by a silicon isotropic wet etch, and the nitride cantilevers were isolated from the substrate completely. Mechanical forces were applied to break the cantilevers. The facets made by microcleaving showed improved roughness as confirmed by surface morphology characterization. The fabrication steps for microcleaved facets combined with laser processing on a full-wafer scale are proposed.