In situ optical monitoring of AlAs wet oxidation using a novel low-temperature low-pressure steam furnace design

To reproducibly define small features by oxidizing AlGaAs layers, it is essential to have good control over the oxidation reaction. We have integrated a glass viewport into a low-pressure (5 torr) cold-walled oxidation chamber to enable in situ optical monitoring of the sample during oxidation. To gain additional control, we reduced the oxidation temperature to 325/spl deg/C, consequently slowing the oxidation rate to 2 μm/h. Real-time in situ optical measurements of AlAs oxidation rates were performed using this system and the results were compared with a standard model. Oxide-semiconductor distributed Bragg reflectors (DBR´s) were also fabricated and measured, yielding highly reflective mirrors suitable for vertical cavity surface-emitting laser (VCSEL) fabrication.