Ellipsometric detection of GaAs(0 0 1) surface hydrogenation in H2 atmosphere

Optical properties of MBE-grown GaAs(0 0 1) surfaces have been studied by spectroscopic ellipsometry under dynamic conditions of ramp heating and cooling after desorption of passivating As-cap-layer with low pressure H₂ atmosphere (14 Torr) applied to the surface. The temperature dependence of GaAs pseudo-dielectric function with atomically smooth (0 0 1) surface carrying the fixed Ga-rich (4 × 2) reconstruction was obtained for the temperature range of 160–600 °C. It is shown ellipsometrically that GaAs(0 0 1) heating in the molecular hydrogen atmosphere results in the formation of hydrogenated layer on the surface.