Nonselective Wet Oxidation of AlGaAs Heterostructure Waveguides Through Controlled Addition of Oxygen

We present data showing that the addition of trace amounts of O ( relative to N ) to N H O process gas during the wet thermal oxidation of Al Ga As enhances the oxidation rates of lower Al content alloys (a tenfold increase for ), while decreasing the oxidation rate selectivity by a factor of seven. An increase in the refractive index from 1.49 to 1.68, and a fourfold decrease in surface roughness, indicates the formation of a denser, higher quality oxide for AlGaAs. Oxides are characterized by prism coupling, atomic force microscopy, and scanning electron microscopy. Thermochemical calculations show a probable mechanism in the enhancement of the dry oxidation reactions of AlGaAs for low levels of O , while there is still an adequate quantity of H produced to reduce As oxides in the wet oxidation process. An AlGaAs quantum well heterostructure p-n laser diode crystal is nonselectively oxidized to create a deep oxide, high-index contrast waveguide with potential applications in semiconductor photonic integrated circuits that require small bend radius, high isolation, low crosstalk optical waveguides.