Quantitative Chemical Depth Profiles of Anodic Oxide on GaAs Obtained by X‐Ray Photoelectron Spectroscopy

Mizokawa, Yusuke; Iwasaki, Hiroshi; Nishitani, Ryusuke; Nakamura, Shōgo

doi:10.1149/1.2129281

Cited by 34 publications

(7 citation statements)

References 10 publications

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“…No literature for the binding energies of arsenic onto CuO could be found. However, several studies have reported the As3d peak of As(V) occurring in this range of binding energies such as; As(V) on synthetic birnessite located at a binding energy of 45.15 eV 35 , at a binding energy of 45.28 eV for arsenopyrite 36 , as well as As(V) peaks at binding energies of 45.7 through 45.9 eV reported by several other researchers 27 37 38 39 40 . For the As3d peak, As(III) binding energies can generally be located at approximately 1 eV lower than the binding energies of As(V) at a range of approximately 44.7 to 45.0 eV 12 41 .…”

Section: Resultsmentioning

confidence: 92%

Intrinsic properties of cupric oxide nanoparticles enable effective filtration of arsenic from water

McDonald¹,

Reynolds

Reddy

2015

Sci Rep

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The contamination of arsenic in human drinking water supplies is a serious global health concern. Despite multiple years of research, sustainable arsenic treatment technologies have yet to be developed. This study demonstrates the intrinsic abilities of cupric oxide nanoparticles (CuO-NP) towards arsenic adsorption and the development of a point-of-use filter for field application. X-ray diffraction and X-ray photoelectron spectroscopy experiments were used to examine adsorption, desorption, and readsorption of aqueous arsenite and arsenate by CuO-NP. Field experiments were conducted with a point-of-use filter, coupled with real-time arsenic monitoring, to remove arsenic from domestic groundwater samples. The CuO-NP were regenerated by desorbing arsenate via increasing pH above the zero point of charge. Results suggest an effective oxidation of arsenite to arsenate on the surface of CuO-NP. Naturally occurring arsenic was effectively removed by both as-prepared and regenerated CuO-NP in a field demonstration of the point-of-use filter. A sustainable arsenic mitigation model for contaminated water is proposed.

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Section: Resultsmentioning

confidence: 92%

Intrinsic properties of cupric oxide nanoparticles enable effective filtration of arsenic from water

McDonald¹,

Reynolds

Reddy

2015

Sci Rep

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“…Because of the small mass difference between Ga and As, bacl~cattering spectroscopy cannot be used to measure compositmn profiles. However the bulk stoichiometry, that is, the Ga plus As concentration relative to the oxygen atom concentration is easily measured from the backscattered yields using the relation (24) No (25) and also Ishii and Jeppson (26) who used an electrolyte similar to ours. The bulk Ga to As ratio in anodic oxides has been measured using Auger spectroscopy (4,6).…”

Section: Resultsmentioning

confidence: 99%

Cation and Anion Transport Numbers in Anodic GaAs Oxides

Fischer

Canaday

1983

J. Electrochem. Soc.

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An Xe TM marker atom layer of concentration 2 • 1015 cm -2 has been implanted into GaAs to a depth of 20 nm. The GaAs containing the Xe TM was anodized to various thicknesses, and Rutherford backscattering was used to measure the change in the Xe TM marker atom depth relative to the change in oxide thickness. These measurements are used to calculate the cation and anion transport numbers which are 0.18 and 0.82, respectively. A secondary result from backscattering measurements is the oxide bulk stoichiometry and oxide density. The results show a bulk oxide composition of (Ga + As): 0 = 2:3, and an oxide density of 4.64 g/cm 3.

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“…In contrast, investigations of film composition have revealed a less unified picture, with examples of relatively uniform films with atomic ratios of Ga to As > 1 [6,7], < 1 [8] and about unity [9], layered films [10] and interfacial enrichments [11][12][13]. The films are generally recognized to consist of Ga 2 O 3 and As 2 O 3 [14], although their precise distributions within the overall oxide are unclear and other species have been reported including As 2 O 5 [15,16]. Furthermore, it is reasonably well established that As 2 O 3 is readily lost from the outer 20 nm or so of the film thickness if films are rinsed in water [17].…”

Section: Introductionmentioning

confidence: 99%

A high-resolution, analytical study of the anodic film formed on GaAs in a tungstate electrolyte

Habazaki

Skeldon

Ghidaoui

et al. 1996

J. Phys. D: Appl. Phys.

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The anodic film formed in aqueous tungstate electrolyte at , to about 295 nm thickness, on -type GaAs at high faradaic efficiency, about 94%, has been examined by analytical transmission electron microscopy, using ultramicrotomed film sections, Rutherford backscattering spectroscopy, x-ray photoelectron spectroscopy, electron probe micro-analysis and scanning electron microscopy. The film is revealed to be amorphous and to comprise a uniform distribution of units of and across the main film thickness, with possible gallium enrichment in the outermost 10 nm or so of the film. Gallium and arsenic are incorporated into the anodic film at the alloy/film interface in the substrate proportions, without development of a layer enriched either in gallium or in arsenic just beneath the anodic film. The formation ratio for the film is about . The film, formed by migration both of cations and of anions across its thickness, is enriched in arsenic relative to the substrate composition, the level of enrichment suggesting that ions migrate outwards in the film about 2.4 times faster than do ions, based on a cation transport number of 0.2. The ions may be ejected, to the electrolyte, under the electric field, on reaching the film/electrolyte interface, with limited formation of an outer layer of essentially at the film/electrolyte interface, or form a layer of , up to about 10% of the total film thickness, which is thinned after anodizing by exposure to the electrolyte and the rinse water. Significantly, the outer layer of film material developed by the faster migrating ions prevents loss of ions from the film during film growth. However, during prolonged exposure to aqueous conditions in the absence of the field, the film becomes enriched in gallium species due to preferential dissolution of arsenic species. The high faradaic efficiency of film growth is a consequence of the presence of a tungsten-enriched layer, probably a gel composed of hydrated tungsten oxide, which develops at the film/electrolyte interface during film growth. No significant presence of tungsten species within the bulk of the anodic film is detected.

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Quantitative Chemical Depth Profiles of Anodic Oxide on GaAs Obtained by X‐Ray Photoelectron Spectroscopy

Cited by 34 publications

References 10 publications

Intrinsic properties of cupric oxide nanoparticles enable effective filtration of arsenic from water

Intrinsic properties of cupric oxide nanoparticles enable effective filtration of arsenic from water

Cation and Anion Transport Numbers in Anodic GaAs Oxides

A high-resolution, analytical study of the anodic film formed on GaAs in a tungstate electrolyte

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