Sealing AlAs against oxidative decomposition and its use in device fabrication

Summary form only given. The native oxides of AlAs and AlGaAs have been studied for their use in device fabrication and their role in device reliability. Although; high-Al-composition AlGaAs is attractive for use in compound semiconductor devices because of its low index of refraction and large electronic band gap relative to GaAs, it decomposes quickly into a porous native oxide when exposed in a room-temperature environment. For example, we have observed a 30-/spl mu/m diameter AlAs-GaAs-InGaAs etched pillar that has deteriorated a distance of -3 /spl mu/m from the perimeter during 11 months in a typical room environment. Such etched pillar structures will therefore suffer long term reliability problems if used for a VCSEL. We present a process that seals an exposed AlAs layer against further oxidative decomposition. The sealant is formed by a rapid thermal annealling.