Sealing AlAs against oxidative decomposition and its use in device fabrication

Data are presented demonstrating that an exposed AlAs layer can be sealed against further decomposition as would otherwise occur due to, for example, wet oxidation. A critical processing step consists of a brief 500–600 °C anneal in forming gas of a previously room ambient exposed AlGaAs surface. In the brief high-temperature anneal, a thin but dense surface barrier layer forms which further blocks diffusing oxygen species. The effectiveness of the surface layer as a barrier is demonstrated through its use as a mask against wet oxidation in the fabrication of an all-epitaxial selectively oxidized multimode AlAs/AlGaAs vertical-cavity laser.