Characterization of etched facets for GaN-based lasers

Dry-etching of laser facets is commonly used for (InAl)GaN/sapphire-based s tructures since the epitaxial planes of the nitride layers are rotated with respect to the substrate planes making cleaving impractical. To achieve st eep and smooth facets by chemically assisted ion beam etching, a 3-layer re sist system is developed for patterning. Characterization by scanning elect ron microscopy and atomic force microscopy shows facets with root-mean-squa re roughnesses of 7 nm and inclination angles of 2-4 degrees. Optically pum ped lasers yield low threshold excitation densities for fully doped separat e confinement heterostructure lasers. (C) 2001 Elsevier Science B.V. All ri ghts reserved.