Dynamic photoinduced low-temperature oxidation of GaAs(110)

Studies of O2 interaction with GaAs(110) at 20 K show dynamic conversion of multilayers of physisorbed O2 into As2O3-like oxides due to the synchrotron radiation beam used to acquire photoemission data (h=90 eV, photon flux 2×1013 cm-2 sec-1). A lower coordination of As and O is observed and is the precursor to As2O3 at the GaAs surface. As2O5-like bonding configurations are also produced when the amount of condensed O2 is increased but this As2O5 is metastable with respect to high-energy photon irradiation. These low-temperature results show the interplay between photoinduced surface chemistry and kinetic constraints on oxygen diffusion over very short distances.