InGaAlAs/InP ridge-waveguide lasers fabricated by highly selective dry etching in CH4/H2/O2 plasma

Demonstration of the highly selective dry etching of InP on InAlAs to produce vertical and smooth etching profiles for InGaAlAs ridge-waveguide lasers is described. The selective and anisotropic etching characteristics were achieved by adding oxygen to the mixture of methane and hydrogen gases used in etching. A low plasma power density was used for both increased selectivity and a lower possibility of plasma-induced damage. With a plasma power density of 0.08 W/cm², and oxygen content of the mixture in the range from 0.5% to 1.0%, the selectivity is a high 60, yielding vertical etching profiles and smooth surface morphology. This selective dry etching process was applied to the fabrication of InGaAlAs ridge-waveguide lasers. The lasing characteristics of the lasers with selectively dry-etched ridge-waveguides are almost as good as those with wet-etched ones, which confirms the damage-free nature of this selective dry-etching process.