Sealing AlAs against oxidative decomposition and its use in device fabrication

Abstract

Summary form only given. We present a process that seals an exposed AlAs layer against further oxidative decomposition. The sealant is formed by a rapid thermal anneal (RTA) to a temperature of /spl sim/500 to 600/spl deg/C in forming gas after brief exposure of the AlAs surface to the typical room environment. The surface barrier layer thus formed is thin and impermeable to diffusing oxygen species, even at elevated temperatures, and can be thermally cycled. An important feature of the surface layer is its ability to fully block, and therefore mask, a steam oxidation of AlAs. To demonstrate its application in device fabrication, the RTA oxide is used to mask certain AlAs layers of an AlAs/GaAs Bragg reflector and thefefore to achieve wet oxidation only in the AlAs layers closest to the active region of an all-epitaxial VCSEL.