Oxygen adsorption on CdTe(1 1 0)

Using a first-principles pseudopotential method we have investigated the adsorption of oxygen atoms over the CdTe(1 1 0) surface. Our calculations suggest that the oxidation process of the CdTe(1 1 0) surface could be understood as follows: (i) an oxygen atom is adsorbed over Cd and Te sites in a bridge configuration; (ii) a second oxygen atom is adsorbed over this system forming an oxygen complex composed of Cd–O2 and Te–O bonds; and (iii) a third oxygen atom is adsorbed over this system forming a new complex with Te–O2–O and Cd–O–O bonds. The final adsorbed complex is characterised by the breaking of the Cd–Te bond and the formation of Te–O, Cd–O and O–O bonds, explaining why apparent contradicting experimental observations are reported by different groups. Our calculated electronic structure for the adsorbed complex suggest that the so expected passivation effect does not occur. In addition we present calculated vibrational modes for the adsorbed system in order to contribute to further experimental investigation.