Using AlN Coatings to Protect the Surface of AlGaAs/GaAs System Heterostructures from Interaction with Atmospheric Oxygen

Thin aluminum nitride (AlN) films have been synthesized by reactive ion–plasma sputtering (RIPS) and their properties have been studied in view of using this method for obtaining protective coatings on output facets of high-power semiconductor laser cavities based on Al x Ga 1 − x As/GaAs heterostructures. Investigations by energy-dispersive X-ray spectroscopy and ellipsometry techniques showed that, at a residual pressure of ~10 –5 Torr, a layer of aluminum oxynitride is formed and the film–substrate heteroboundary may experience to oxidation. However, AlN films with thicknesses on the order of 100 nm grown in pure nitrogen at a residual pressure of ~10 –7 Torr were evidently free of oxygen and could reliably prevent its penetration to the region of heteroboundary.