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.