X-ray photoelectron spectroscopy study of the first stages of ZnO growth and nanostructure dependence of the effects of polarization at ZnO/SiO2 and ZnO/Al2O3 interfaces

Abstract

Articles you may be interested inAnalysis of electronic structure of amorphous InGaZnO/SiO2 interface by angle-resolved X-ray photoelectron spectroscopy A critical characteristic of nanoparticles and, in general, of nanomaterials, is the overweighing importance of the surface and interface layers relative to the bulk because of the small size of the aggregates ͑in three dimensions͒ or thickness of the layers ͑in the case of two dimensions͒ that constitute the nanomaterial. This article reports the characterization of interface layers of ZnO/MO x (MO x : Al 2 O 3 and SiO 2 ) using x-ray photoelectron spectroscopy ͑XPS͒. Careful experiments consisting of the deposition of ZnO material on SiO 2 and Al 2 O 3 substrates have been performed. Several samples were produced and characterized in situ. The nanostructure of the first stages of growth of the ZnO deposited was determined by Tougaard peak-shape analysis of several photoelectron peaks in both the substrate and overlayer and the growth mechanisms determined were found to be consistent. Thus, the actual nanostructure of the growing ZnO films was carefully determined. In addition, the chemical interaction at the ZnO/MO x interface was monitored by following the variation of the Auger parameter of the Zn atoms as the amount of ZnO deposited was increased. Thus, changes of the Auger parameter of the Zn atoms were correlated with the actual nanostructures formed by the ZnO deposits. From this information, a model is presented that accounts for changes in the electronic parameters determined by XPS as a result of bonding and polarization interaction at the interface.

Determination of amount of substance for nanometre‐thin deposits: consistency between XPS, RBS and XRF quantification

“…Note that analysis of the three peaks (two from atoms in the overlayer and one from atoms in the substrate) gives reasonably consistent morphologies for the ZnO films grown. 10 As discussed below, the lower island height determined by analysis of the Zn 2p peak for the tallest islands is consistent with the lower probing depth of the low-energy Zn 2p electrons compared with the high-energy Si KLL, Al KLL and Zn LMM electrons.…”

“…Under these conditions, the deposition rates were 0.1-0.2 nm min 1 . 10 After each deposition the samples were always exposed for a few minutes to the plasma of oxygen without precursor, to ensure full oxidation and removal of carbonaceous traces from the surface of the substrate. Three different substrates were used: SiO 2 thermally grown (¾100 nm thick) on Si(100); a single crystal of sapphire ˛-Al 2 O 3 ; and an Al 2 O 3 /Al substrate obtained by bombarding a high-purity Al foil with 3 keV O C 2 ions.…”

Epitaxial growth of ZnO films on thin FeO(111) layers

“…However, the corresponding Auger parameter (a ¼ BE (Zn 2p 3/2 )+ KE (Zn LMM), KE = kinetic energy) value is 2010.6 eV, which strongly suggests the existence of Zn 2+ , i.e. the formation of ZnO for as-prepared thin films [16][17][18]. In addition, from AE spectra, the ratio of Zn to O being 0.95:1 supports the formation of ZnO film.…”

First nucleation steps during deposition of SiO2 thin films by plasma enhanced chemical vapour deposition

“…General spectra in a binding energy (BE) region from À200 to 1100 eV were recorded. Selected regions of these spectra were used for the peak shape analysis [19]. In addition, zone spectra with better resolution were recorded for the different peaks to get more precise chemical and/or electronic information of the layer.…”