Oxidation of Sulfur-Treated GaAs Surfaces Studied by Photoluminescence and Photoelectron Spectroscopy

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Abstract
The initial oxidation features of (NH4)2S x -treated GaAs have been investigated by photoelectron spectroscopy in order to correlate the photoluminescence (PL) degradation caused by oxidation with band bending and surface chemical bonding changes. Direct correlation between PL degradation and the Ga oxide formation resulting in drastic upward band bending is observed. It is also found that the S-passivated surface consisting of 1 to 2 ML Ga-S layer comparatively inhibits oxidation reaction, and that the underlying GaAs is oxidized leaving the surface Ga-S layer unoxidized. This indicates a possibility of reducing PL degradation by forming a thicker Ga-S passivation layer.