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

Martín-Concepción, A. I.; Yubero, F.; Espinós, J.P.; Garcı́a-López, J.; Tougaard, S.

doi:10.1002/sia.1635

Cited by 11 publications

(7 citation statements)

References 16 publications

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“…8,9,16 The measured spectra J͑E͒, the primary excitation spectra F͑E͒ ͑excited spectrum before electron transport͒, the indepth concentration profile f͑z͒ ͑where z is the depth below the surface͒, and the inelastic electron scattering cross section K͑T͒ for an energy loss T are linked within electron transport theory, which for the particular case of normal emission reads…”

Section: Experimental and Methodsmentioning

confidence: 99%

X-ray photoelectron spectroscopy study of the nucleation processes and chemistry of CdS thin films deposited by sublimation on different solar cell substrate materials

Espinós

Martín-Concepción

Мансилла

et al. 2006

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Cadmium sulfide has been deposited by evaporation on five different substrates: CdTe, ZnO, Ag, TiO2, and partially reduced titanium oxide (i.e., TiO1.73). The deposition rate and the evolution of the Cd∕S ratio on the different substrates have been determined by x-ray photoelectron spectroscopy. The growth mode of the films has been also studied by analyzing the shape of the backgrounds behind the photoemission peaks (peak shape analysis). It has been found that, under completely equivalent conditions, the deposition efficiency (i.e., sticking coefficient) is large on CdTe and TiO1.73, but very small on ZnO and TiO2. Silver constitutes an intermediate situation characterized by a long induction period where the deposition rate is small and a later increase in deposition efficiency comparable to that on CdTe. For the initial stages of deposition, below an equivalent monolayer, it has been also found that the Cd∕S ratio is smaller than unity on TiO1.73 and ZnO but larger than unity on CdTe and Ag substrates. For sufficiently long deposition times the Cd∕S ratio on the surface reaches unity. Except for silver substrate, cadmium appears as Cd2+ and sulfur as S−2 species at the initial stages of deposition. On the silver surface, cadmium adsorbs as Cd0 at low coverage. Peak shape analysis has shown that cadmium sulfide grows according to layer-by-layer mechanism (Frank–van de Merwe model) when the substrates are CdTe and TiO1.73, but large particles are formed that do not cover the surface for ZnO and Ag substrates (Volmer-Weber growth model). These results are consistent with the different chemical affinities of the substrate towards the atoms of cadmium and sulfur produced during the evaporation of the cadmium sulfide.

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Section: Experimental and Methodsmentioning

confidence: 99%

X-ray photoelectron spectroscopy study of the nucleation processes and chemistry of CdS thin films deposited by sublimation on different solar cell substrate materials

Espinós

Martín-Concepción

Мансилла

et al. 2006

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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“…Finally, the ZnO-3 sample (i.e., 400°C/60 min, Fig. 1c), used as control thick film, shows a homogeneous granular morphology characterized by fairly welldefined round grains having average dimensions of about 10-15 nm [30]. The morphological results provide confidence about two different ZnO deposition mechanisms, depending on the specific deposition temperature used.…”

Section: Physicochemical Characterization Of Ultrathin Zno-based Filmsmentioning

confidence: 79%

“…Experiments were carried out with the standard Al Ka radiation source (hm = 1486.6 eV) at a base pressure of 2 Â 10 À9 Torr. XPS spectra were collected at a photoelectron take-off angle of 45°, which, according to the effective attenuation length values, respectively, of 0.74 nm, for photoelectron from Zn 2p traveling in ZnO [30], and of 3.13 nm, for Si 2p photoelectrons in an organic layer [31], roughly corresponds to an actual sampling depth in the range from about 1.6 nm (bulk ZnO) up to about 6.4 nm (bulk SiO 2 ). Both survey and narrow region scans were recorded, namely Zn 2p, C 1s, Si 2p, O 1s and N 1s peaks, at pass energy and incremental step size of 150 eV/1 eV for survey and 11.85 eV/0.05 eV for the narrow scans, respectively.…”

Section: Physicochemical Characterization Of the Protein-zno Biointermentioning

confidence: 99%

Ultrathin and nanostructured ZnO-based films for fluorescence biosensing applications

Satriano

Fragalà

Aleeva

2012

Journal of Colloid and Interface Science

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a b s t r a c tThe fluorescence-based sensing capability of ultrathin ZnO-SiO 2 nanoplatforms, deposited by an integrated approach of colloidal lithography and metal organic chemical vapor deposition, has been investigated upon adsorption of fluorescein-labeled albumin, used as model analyte biomolecule. The protein immobilization process after spontaneous adsorption/desorption significantly enhances the green emission of the different ZnO-based films, as evidenced by scanning confocal microscopy, corresponding to a comparable protein coverage detected by X-ray photoelectron spectroscopy. Moreover, experiments of fluorescence recovery after photobleaching evidence that the protein lateral diffusion at the biointerface is affected by the chemical and/or topographical patterning of hybrid ZnO-SiO 2 surfaces. The used approach is very promising for biomolecular detection applications of these ZnO-SiO 2 nanoplatforms, by simple sizing of the 2D vs. 3D patterning design, which in turn is accomplished by the fine tuning of the integrated colloidal lithography-chemical vapor deposition processes.

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“…Note that the consistency of the relative thicknesses is very good. The previous analysis made by XPS peak shape analysis 1 showed that the ZnO grows in the form of islands. This will give rise to a shadowing effect which depends on the details of the shape and distribution of the aggregates.…”

Section: Analysis Of the Thin Zno Filmsmentioning

confidence: 99%

“…In a recent study, 1 we compared the three techniques: XPSpeak shape analysis, Rutherford backscattering spectroscopy (RBS) and x-ray fluorescence spectrometry (XRF) for their ability to consistently determine the total amount of Zn atoms in ¾1 nm-10 nm thin ZnO films grown on the three substrates: SiO 2 , Al 2 O 3 and an Al foil with a thin Al 2 O 3 layer. The relative values were found to be consistent to within ¾15-20%.…”

Section: Introductionmentioning

confidence: 99%

Surface roughness and island formation effects in ARXPS quantification

Martín-Concepción¹,

Yubero²,

Espinós³

et al. 2004

Surface & Interface Analysis

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Quantification of surface nano-structures by angle-resolved XPS (ARXPS) is straightforward and works quite reliably for perfectly flat surfaces of amorphous materials. For rough surfaces, the interpretation of ARXPS is, however, complicated because the angular variation of the XPS peak intensity depends on the surface roughness. Even for ideally flat substrates, ARXPS analysis of laterally inhomogeneous surface structures grown on the surface is quite complex. The reason is that neighboring nano-clusters shadow the XPS peak intensity. The effect depends on cluster shape as well as the distribution of clusters on the surface. In addition the effects depend on the flatness of the underlying substrate. The interpretation of ARXPS then becomes quite complex. In the present paper, we have studied this problem by analyzing ZnO nano-clusters grown on substrates of SiO 2 and Al 2 O 3 . Thus we compared the results of quantification by the four techniques: ARXPS, XPS-peak shape analysis, Rutherford backscattering spectroscopy and x-ray fluorescence spectrometry. While the latter three techniques gave consistent results, the results of the ARXPS analysis were way off. This deviation is discussed in terms of the above-mentioned shadowing effect of neighboring clusters as well as roughness of the underlying substrates. Different normalization methods in the ARXPS analysis procedure are compared and it is found that some of the observed problems for the substrate peaks (but not for the peaks from the overlayer film) can be reduced by applying reference samples with similar roughness for normalization of the data. In conclusion, the ARXPS technique is very much dependent on surface roughness as well as on the morphology of the thin films. Thus for reliable quantification with ARXPS it is necessary to have independent knowledge on surface roughness as well as the distribution of islands of the thin films.

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

Cited by 11 publications

References 16 publications

X-ray photoelectron spectroscopy study of the nucleation processes and chemistry of CdS thin films deposited by sublimation on different solar cell substrate materials

X-ray photoelectron spectroscopy study of the nucleation processes and chemistry of CdS thin films deposited by sublimation on different solar cell substrate materials

Ultrathin and nanostructured ZnO-based films for fluorescence biosensing applications

Surface roughness and island formation effects in ARXPS quantification

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