XPS study of arsenic doped ZnO grown by Atomic Layer Deposition

• ZnO:As films were obtained by annealing of the ZnO–ALD sample in the As atmosphere.
• The As3d XPS spectra show 3 contributions observed at BE of 48 eV, 41 eV and 45 eV.
• For annealing temperature of 950 °C the As3d component at the BE of 45 eV dominates.
• This effect is accompanied acceptor bound excitons observed in a low temperature PL.
• It supports the suggestion that the 45 eV component comes from AsZn–2VZn complexes.

Arsenic-doped ZnO films were formed by thermal annealing of epitaxial ZnO films grown by Atomic Layer Deposition (ALD) in arsenic atmosphere at temperature 850–950 °C. X-ray photoelectron spectroscopy (XPS) studies of the ZnO:As films revealed the complex As3d core level spectra formed by three components located at about 41 eV, 45 eV and 47.5 eV below the Fermi level. The As3d component at binding energy (BE) of 45 eV was found to be correlated with the acceptor bound A°X exciton state observed in low temperature photoluminescence. This observation strongly supports the previously postulated assumption that the origin of the 45 eV component of the As3d spectra can be ascribed to arsenic atoms in AsZn–2VZn complexes formed as a result of high temperature annealing. This assumption is also supported by the evident valence band shift towards the Fermi level in the ZnO:As film annealed at 950 °C.