In situ observation of nitridation of GaAs (001) surfaces by infrared reflectance spectroscopy

Nitridation of GaAs (001) surfaces grown by molecular beam epitaxy is observed by detecting the surface reflectance change caused by the formation of Ga-N and As-N bonds. Nitridation is performed by exposing (4 × 2) or (2 × 4) surfaces to atomic nitrogen generated with a heated tungsten filament in an As-free environment. Nitridation of the Ga-rich (4 × 2) surface results in a single reflectance peak at 1200 cm−1 attributed to the formation of Ga-N bonds, while nitridation of the As-rich (2 × 4) surface results in another peak at 1000 cm−1 attributed to As-N bonds in addition to the Ga-N peak.