Kinetics of AlAs steam oxidation at low pressure and low temperature measured in-situ using a novel furnace design with an integral optical port

Oxidation of AlGaAs layers has become a critical processing step in the fabrication of high-performance vertical-cavity surface-emitting lasers (VCSELs). The low refractive index of the oxide provides for high-contrast distributed Bragg reflector (DBR) mirrors, while the high oxide resistivity makes it ideal for defining VCSEL current apertures. We have integrated a glass viewport into a low-pressure (5 Torr) cold-walled oxidation chamber to allow in-situ optical monitoring of the oxidation reaction, enabling superior control and reproducibility. Real-time, in-situ optical measurements of AlAs oxidation rates were performed and we compare the results with a standard model. Oxide-semiconductor DBRs were also fabricated and we present reflectivity measurements on these samples.