Bulk Metal Oxides as a Model for the Electronic Properties of Passive Films

Schmuki, Patrik; Büchler, Markus W.; Virtanen, Sannakaisa; Böhni, H.; Müller, Randoald; Gauckler, Ludwig J.

doi:10.1149/1.2049984

Cited by 65 publications

(44 citation statements)

References 4 publications

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“…In such a case further information gathered by other (possibly in situ) analytical techniques are necessary to rationalise PCS data of passive films. Other authors [167][168][169] have proposed a different route for the identification of passive film. According to these authors a comparison of PCS data (as well as of the general semiconducting behavior) between passive films anodically grown and sputtered oxides could help to identify the nature of passive films.…”

Section: (V) Pcs Analysis Of Passive Films and Corrosion Layers On Bamentioning

confidence: 99%

Physicochemical Characterization of Passive Films and Corrosion Layers by Differential Admittance and Photocurrent Spectroscopy

Quarto

Mantia

Santamaria

2009

Modern Aspects of Electrochemistry

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Section: (V) Pcs Analysis Of Passive Films and Corrosion Layers On Bamentioning

confidence: 99%

Physicochemical Characterization of Passive Films and Corrosion Layers by Differential Admittance and Photocurrent Spectroscopy

Quarto

Mantia

Santamaria

2009

Modern Aspects of Electrochemistry

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“…11, the photocurrent spectra of coated EP-Al samples differred greatly from that of bare EP-Al sample because of the onset of a large photocurrent contribution in the region of wavelengths around 300 nm. It has been reported that photocurrent spectra of chromium oxides passive films show maxima 16,17 in the same wavelength range. By assuming the presence of nondirect ͑indirect for crystalline materials͒ optical transitions between valence band ͑VB͒ and conduction band ͑CB͒ of a CCC, and a direct proportionality between the photocurrent yield, I ph , ͑see above͒ and the light absorption coefficient ␣, 12 the following equation holds…”

mentioning

confidence: 97%

“…This behavior is also reminiscent of analogous behavior of Cr passive films. 16,17 In order to determine the flatband potential, V FB , for the different films we used two different approaches depending from the fact that the blocking region of the I tot vs. U E plots was more or less wide. In fact in some cases the inversion photocurrent potential was accessible by recording the I ph vs. U E plots at different , before the increase of the total current ͑see Fig.…”

mentioning

confidence: 99%

Structural Analysis and Photocurrent Spectroscopy of CCCs on 99.99% Aluminum

Quarto

Santamaria

Mallandrino

et al. 2003

J. Electrochem. Soc.

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A characterization of chromate conversion coatings ͑CCCs͒ formed in the presence and in the absence of accelerator ͑ferro-ferricyanide redox couple͒ has been performed by various techniques ͑transmission electron microscopy, TEM, glow discharge optical emission spectrometry, GDOES, X-ray absorption near-end structure, XANES, and photon correlation spectroscopy͒. The results of a detailed investigation on morphological, compositional, and solid-state properties of freshly converted aluminum samples at different immersion times ͑30 s-90 min͒ are reported. The TEM and GDOES data suggest the presence of iron-cyanide species only in the external layer of CCC of nearly constant thickness. The XANES data suggest the presence of both Cr͑VI͒ and Cr͑III͒ species with a ratio Cr͑VI͒/Cr͑III͒ close to 1:2. This ratio remains constant with the conversion time and seems slightly affected by the composition of conversion solution. The photoelectrochemical study suggests an insulating or slightly p-type behavior for CCC layers. A bandgap value of about 2.55 eV has been estimated, regardless of the conversion solution, although some differences in the photocurrent spectra have been observed for coatings formed in the presence or absence of accelerator. The location of electronic energy levels of the Al/CCC/electrolyte interface has been derived which could account for the different kinetics of coating formation in the presence of accelerator. A large research effort has been devoted in the last years to the understanding of the exact nature of the chromate conversion coating ͑CCC͒ and its mechanism of protection against corrosion of aluminum metal and alloys.Surface analysis techniques have revealed that the composition of the coatings depends on the nature of the chemical conversion bath.1-3 It is now agreed that the coatings are amorphous 2,3 and that both Cr͑III͒ and Cr͑VI͒ species are incorporated into the films, with possible formation of a mixed Cr͑III͒-Cr͑VI͒ oxide as suggested by recent Raman spectroscopy analysis. 4,5 The mechanism of action of chromate in assuring the protection against pitting corrosion is still under debate. From this point of view a large interest exists in understanding the influence of aging on the protection action of CCCs. It has been shown that long-term or temperature aging acts on the mechanism of release of Cr͑VI͒ species so affecting the ''active protection'' of CCCs also called self-healing. In this frame different hypothesis have been suggested to explain the associated loss of corrosion protection.5-9 Among those, structural changes occurring into the CCC and related to dehydration were evidenced. 10As for the mechanism of formation and growth of CCCs only very few papers have addressed both the role of the redox couples, usually added to the commercial conversion bath to speed up the growth of the coating, and the mechanism of initial formation of CCCs during the conversion process. 3,4 Brown et al.3 suggested that on a very pure Al surface a uniform coating develops due to a mechanism o...

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“…The electrochemical micro cell was connected to an Autolab PGStat30 Potentiostat from Metrohm and for further data processing to a computer [19]. The EIS measurements were carried out with perturbation amplitude of ±10 mV in a frequency range from 100 KHz to 10 mHz.…”

Section: Exprimentalmentioning

confidence: 99%

“…Manuscript received Aug. 16,2011; revised Jan. 19,2012. Dechema e.V., Theodor Heuss-Allee 25, D-60486 Frankfurt, Germany E-mail : Tesfu@dechema.de, T.Tesfu@gmx.de…”

Section: Introductionunclassified

Implementation of Electrochemical Methods for Metrology and Analysis of Nano Electronic Structures of Deep Trench DRAM

Zeru¹,

Schroth²,

Kuecher³

2012

JSTS:Journal of Semiconductor Technology and Science

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Abstract-In the course of feasibility study the necessity of implementing electrochemical methods as an inline metrology technique to characterize semiconductor nano structures for a Deep Trench Dynamic Random Access Memory (DT-DRAM) (e.g. ultra shallow junctions USJ) was discussed. Hereby, the state of the art semiconductor technology on the advantages and disadvantages of the most recently used analytical techniques for characterization of nano electronic devices are mentioned. Various electrochemical methods, their measure relationship and correlations to physical quantities are explained. The most important issue of this paper is to prove the novel usefulness of the electrochemical micro cell in the semiconductor industry.

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Bulk Metal Oxides as a Model for the Electronic Properties of Passive Films

Cited by 65 publications

References 4 publications

Physicochemical Characterization of Passive Films and Corrosion Layers by Differential Admittance and Photocurrent Spectroscopy

Physicochemical Characterization of Passive Films and Corrosion Layers by Differential Admittance and Photocurrent Spectroscopy

Structural Analysis and Photocurrent Spectroscopy of CCCs on 99.99% Aluminum

Implementation of Electrochemical Methods for Metrology and Analysis of Nano Electronic Structures of Deep Trench DRAM

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