High-spin configuration of Co(III) in nonstoichiometric Co3O4 films. XPS investigations

Growth and characterization of thin epitaxial Co3O4(1Vaz1, Henrich2, Ahn3 et al. 2009Journal of Crystal Growth32150View full textAdd to dashboardCite

“…The O 1s photoemission line is also similar before and after annealing. The additional shoulder observed at higher binding energies has been attributed to adsorbed oxygen [13,51,[57][58][59][60][61][62] or to surface hydroxylation [13,52]; for the annealed sample the shoulder is much more pronounced compared to the as-grown film, consistent with surface hydroxylation through water adsorption upon exposure to air. The surface morphology was also probed ex situ using AFM in contact mode at room temperature.…”

Magnetic and electronic characterization of highly Co-doped ZnO: An annealing study at the solubility limit

“…26,27 Both the increase in peak width and spin-orbit splitting of the Co 2+ component compared to the Co 3+ component has been described to be an effect of multiplet splitting of the high spin Co 2+ ͑S =3/ 2͒ which is absent for the low spin Co 3+ ͑S =0͒. [28][29][30] The splitting into main and satellite lines are due to different final states after the photoemission of a Co 2p core-level electron. In the Co 2+ spectrum the main lines are due to a 2p 5 3d 8 L −1 final state, where L −1 is a hole in the ligand while the satellites are due to a 2p 5 3d 7 L final state.…”

Interface and electronic characterization of thin epitaxial films

“…While this could explain the shoulder in the O 1s peak of the Co 3 O 4 XPS spectra [33,37], it is unlikely that it would give the same signature in the two cases. In fact, the shoulder is identical for both terminations, with little variation in energy and intensity for both the as-grown samples, measured immediately after growth, and for the annealed samples, which are cleaned in an O-plasma after been exposed to air (this shoulder is often assigned to adsorbed O [32,38,39]). Therefore, assignment of the shoulder to H on the surface cannot provide the needed screening for both surfaces.…”

“…The O 1s photoemission line is also similar before and after annealing, although some variation in the shape of the O 1s line is observed. This could be related, in some instances, to the effect of the O-plasma cleaning procedure (at room temperature) before XPS spectra collection: given the surface sensitivity of XPS, small variations in the amount of surface adsorbed O may lead to slight variations in the O 1s line; in fact, the additional peak observed at higher binding energies has been attributed to adsorbed oxygen [20,32,37,38,39,40,41,42], although surface hydroxylation, which also yields a similar peak [33,37], cannot be ruled out.…”