Lateral Oxidation of AlAs for Circular and Inverted Mesa Saturable Bragg Reflectors

A model of the thermal oxidation kinetics that is based on the continuity equation is adapted to the fabrication of circular saturable Bragg reflector (SBR) mesa structures, as well as inverted mesa array structures. A comparison between theoretical calculations and experimental measurements shows good agreement, making the model a useful tool for the controllability of the structure-dependent oxidation process. The model is applied to the wet oxidation of buried AlAs layers for the fabrication of ultra-broadband, high index contrast, III-V/ AlxOy SBRs. The rate of oxidation is found to be dependent not only on the oxidation temperature, but also on oxidation time, mesa geometry, and AlAs layer thickness. The two distinct large-area SBR structures, the circular mesa and the inverted mesa, are fabricated.