Initial oxidation of gallium arsenide (001)-β2(2 x 4) surface using density functional theory

The initial oxidation of a gallium arsenide (001)-β2(2 x 4) surface with an oxygen molecule was investigated using density functional theory. The oxygen molecule was adsorbed on the surface without any energy barrier. The dissociation of the oxygen molecule on the first arsenic layer had two dissociation paths; the inter-dimer and intra-dimer. The inter-dimer dissociation was the dominant dissociation path based on the energy barriers. The two dissociated oxygen atoms preferred breaking the arsenic-gallium back-bond to form arsenic-oxygen-gallium bonds. Our results are in good agreement with literature of the scanning tunneling microscope study.