Core and valence band photoelectron spectroscopic studies of nickel oxidation in an anaerobic liquid cell

Liang, Yuanling; Paul, Dilip K.; Xie, Yaoming; Sherwood, Peter M. A.

doi:10.1021/ac00065a018

Cited by 29 publications

(20 citation statements)

References 31 publications

(4 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To do this, XPS measurements have also been performed on the Ni-covered samples with F treatment and 400 o C annealing. The direct determination of VBM-E F of Ni/AlGaN is difficult as the VB spectra of Ni metal dominate the high kinetic energy region of the spectrum [17], as shown in Fig. 4.…”

Section: Modification Of the Intrinsic Sbh φβ By Cf 4 Plasma Treatmentmentioning

confidence: 99%

Surface properties of Al_xGa_1‐xN/GaN heterostructures treated by fluorine plasma: an XPS study

Huang

Chen

2011

Phys. Status Solidi C

View full text Add to dashboard Cite

The variations in surface potential and the Schottky barrier height ΦB in fluorine‐plasma‐treated AlxGa1‐xN/GaN heterotructures are systematically studied by x‐ray photoelectron spectroscopy (XPS), giving insights into the mechanisms underlying the strong threshold voltage shift in AlxGa1‐xN/GaN HEMTs by the F plasma treatment technology. It is found that the treatment resulted in a fluorinated surface containing masses of AlF3, with the surface potential of Al0.25Ga0.75N/GaN heterostructure increased by ∼0.38 eV during the first 60 seconds of the treatment. Annealing at 400 °C in N2 ambient for 10 minutes does not affect the surface potential, but results in quick reduction of AlF3, consistent with the relative poor thermal stability of AlF3 reported in literature. ΦB between Ni and F‐plasma‐treated Al0.25Ga0.75N surface was extrapolated from the shift in Ga 2p3/2 core‐level and exhibits a small increase of 0.20 eV. The enhanced ΦB is much smaller than the positive shift in Vth observed from HEMTs fabricated with the same treatment conditions, suggesting that the primary factor responsible for the conversion from depletion‐mode to enhancement‐mode AlxGa1‐xN/GaN by F plasma treatment is not the surface modifications, but rather the negative fixed charges carried by F ions in AlxGa1‐xN/GaN heterostructures. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

show abstract

Section: Modification Of the Intrinsic Sbh φβ By Cf 4 Plasma Treatmentmentioning

confidence: 99%

Surface properties of Al_xGa_1‐xN/GaN heterostructures treated by fluorine plasma: an XPS study

Huang

Chen

2011

Phys. Status Solidi C

View full text Add to dashboard Cite

show abstract

“…This ''anaerobic cell'' is specially designed to allow study of the solid-liquid interface by liquid exposure or electrochemical treatment under inert atmosphere. 3 The base pressure of the system is better than 10 Ϫ9 Torr.…”

Section: Methodsmentioning

confidence: 99%

“…3 We have found that a number of metals ͑aluminum, 1 iron, 1 and copper 2 ͒ when exposed to deoxygenated orthophosphoric acid at negative potentials ͑versus saturated calomel electrode͒, or in appropriate cases to the same acid at the rest potential, form a surface that is covered with a thin ͑less than 50 Å͒ layer of phosphate. When first exposed the phosphate is in the form of a condensed phosphate, which we believe to be in the form of metaphosphate (P 4 O 12 4Ϫ ).…”

Section: Introductionmentioning

confidence: 99%

Formation of potentially protective oxide-free phosphate films on titanium characterized by valence band x-ray photoelectron spectroscopy

Rotole

Gaskell

Comte

et al. 2001

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

Self Cite

View full text Add to dashboard Cite

Articles you may be interested inThin oxide-free phosphate films of composition formed on the surface of vanadium metal and characterized by xray photoelectron spectroscopyValence band x-ray photoelectron spectroscopic investigation of surface cleanliness of aluminum metal and its alloys J.This paper reports the results of a continuing study focused on preparing novel surface chemistries on metal surfaces. In this paper we report how it is possible to prepare oxide-free titanium metal surfaces protected by a film consisting of phosphate. The surface is prepared by electrochemical treatment in an anaerobic cell which allows electrochemistry to be conducted on samples located in a vacuum system attached to an x-ray photoelectron spectrometer. When a clean metal surface is subjected to electrochemical treatment in aqueous orthophosphoric acid an oxide-free phosphate film can be formed on the metal which is stable on subsequent air exposure. Compositional variations were found with potential and other factors. Identical electrochemical treatment of as-received titanium metal yielded samples that had a surface consisting largely of oxide. The chemical composition of these surface films was studied by core level and valence band x-ray photoelectron spectroscopy. Valence band photoemission interpreted by band structure calculations was found to be especially effective in understanding subtle differences in surface chemistry, enabling the clear identification of phosphate ͑being able to distinguish between orthophosphate and metaphosphate films͒ and its distinction from surface oxide. Valance band spectra calculated from band structure calculations for TiO, Ti 2 O 3 , TiO 2 , TiC, TiPO 4 , and TiP 2 O 7 are reported.

show abstract

“…1,2 These films are interesting because they contain no oxide and are thin, generally thinner than 100 Å. 1,2 These films are interesting because they contain no oxide and are thin, generally thinner than 100 Å.…”

Section: Introductionmentioning

confidence: 99%

“…The focus of the experimental work will be the use of valence band photoemission, which we have already shown to be effective in distinguishing between phosphate and oxide, [1][2][3][4][5] and in the identification of subtle chemical differences. We report the results of two photon sources; x-ray light provides information at a greater depth than UV light allowing us to nondestructively ''profile'' through the interface region.…”

Section: Introductionmentioning

confidence: 99%

Interfacial interactions of polymer coatings with oxide-free phosphate films on metal surfaces

Wang

Sherwood

2003

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

Self Cite

View full text Add to dashboard Cite

Thin oxide-free phosphate films of composition formed on the surface of vanadium metal and characterized by xray photoelectron spectroscopy A method for producing thin oxide-free phosphate films using an easier process than those previously reported is described. The process is carried out under ambient conditions using aqueous phosphoric acid. The chemistry of the phosphated surface prepared by the process and the interaction of this surface with a thin film of polyvinyl alcohol ͑PVA͒ are examined with the purpose of evaluating the potential of this film to serve as an adhesion promoting layer. The surface chemical changes are monitored by core and valence band x-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy, with the resultant spectra compared to those from band structure calculations. Valance band photoemission interpreted by band structure calculations can be used to study the interfaces involved, and proves to be a very effective tool for conclusively identifying the surface species present. The process for forming oxide-free phosphate films forms the same surface chemistry as previously reported for other processes. PVA is found to strongly interact with the oxide-free phosphate film on aluminum metal illustrating the potential of such films as adhesion promoters.

show abstract

Core and valence band photoelectron spectroscopic studies of nickel oxidation in an anaerobic liquid cell

Cited by 29 publications

References 31 publications

Surface properties of Al_xGa_1‐xN/GaN heterostructures treated by fluorine plasma: an XPS study

Surface properties of Al_xGa_1‐xN/GaN heterostructures treated by fluorine plasma: an XPS study

Formation of potentially protective oxide-free phosphate films on titanium characterized by valence band x-ray photoelectron spectroscopy

Interfacial interactions of polymer coatings with oxide-free phosphate films on metal surfaces

Contact Info

Product

Resources

About

Core and valence band photoelectron spectroscopic studies of nickel oxidation in an anaerobic liquid cell

Cited by 29 publications

References 31 publications

Surface properties of AlxGa1‐xN/GaN heterostructures treated by fluorine plasma: an XPS study

Surface properties of AlxGa1‐xN/GaN heterostructures treated by fluorine plasma: an XPS study

Formation of potentially protective oxide-free phosphate films on titanium characterized by valence band x-ray photoelectron spectroscopy

Interfacial interactions of polymer coatings with oxide-free phosphate films on metal surfaces

Contact Info

Product

Resources

About

Surface properties of Al_xGa_1‐xN/GaN heterostructures treated by fluorine plasma: an XPS study

Surface properties of Al_xGa_1‐xN/GaN heterostructures treated by fluorine plasma: an XPS study