Vertical-cavity surface-emitting lasers fabricated using a sealing of AlAs against wet oxidation

We have studied the process of sealing an exposed AlAs and the wet oxidation behavior of AlAs to prevent further wet oxidation. A critical processing step consists of the formation of an oxide surface barrier by the first wet oxidation for a short time at 390 - 430 °C in the steam environment of previously room-ambient exposed AlAs surface. During this brief wet oxidation, a dense oxide barrier with a thickness of ∼ 1 μm is formed, which further blocks diffusing oxygen species during the second wet oxidation. The oxide surface barriers of ∼ 1 μm thickness formed at 408 °C and 410 °C have shown the best effectiveness of sealing against further wet oxidation. The effectiveness of the sealing is demonstrated through its use as a mask against wet oxidation in the fabrication of oxide-confined vertical-cavity surface-emitting lasers.