Thin-film semiconductor sensors for hyperthermal oxygen atoms

Osborne, J. J.; Roberts, G.T.; Chambers, A.R.; Gabriel, S.B.

doi:10.1016/s0925-4005(00)00298-7

Cited by 13 publications

(13 citation statements)

References 20 publications

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“…This suggests that the AO adsorbs onto the ZnO, depleting the charge carriers near the surface. This type of response to AO was also noted by Osborne [9]- [11] for the thin ZnO films from which his sensors were fabricated, except that the response rapidly became non-linear and the resistance (or, rather, conductance in his case) reached an asymptotic value as the sensors became saturated with AO. In the present experiments there was no indication of sensor saturation.…”

Section: DC Resistance Experimentssupporting

confidence: 72%

“…Osborne [9]- [11], following a theoretical treatment originally proposed by Langmuir [26] and later by Haberreker et al [27], developed a model for AO adsorption and its effect on the conductance (inverse resistance) of a semi-conductor film. Some of the results from that model will be quoted here, but the reader is referred to [9] for details of the derivation.…”

Section: Discussionmentioning

confidence: 99%

“…The latter observation is somewhat surprising, since zinc oxide is normally considered to be UV photoconductive [20]; in similar control experiments Osborne [9], [11] demonstrated that his thin-film ZnO sensors, protected from AO by a thin film of silica, decreased in resistance when exposed to the ATOX-induced UV radiation. The apparent lack of UV-response noted in the present thick film sensors is attributed to the fact that the UV can penetrate only just beneath the surface of the thick film (e.g.…”

Section: DC Resistance Experimentsmentioning

confidence: 99%

“…Past experience at the University of Southampton [9]- [11] with sensors fabricated using thin (~ 1μm), sputtered films of zinc oxide has shown that atomic oxygen adsorbs to the surface of zinc oxide, an n-type semi-conductor material, with negligible diffusion into the bulk, removing some of the electronic density available for conduction and thereby increasing the resistance of the sensor; this change in resistance can be used to estimate atomic oxygen flux. The sensors were observed to saturate rather quickly, i.e.…”

Section: Introductionmentioning

confidence: 99%

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Development of a Reusable Atomic Oxygen Sensor Using Zinc Oxide Thick Films

et al. 2013

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1 The paper describes the fabrication and testing of thick film zinc oxide sensors that could be used to monitor the atomic oxygen fluence experienced by spacecraft in low Earth orbit, or that produced in ground-based atomic oxygen sources. Impedance spectroscopy measurements were carried out on the sensors to determine the conduction mechanisms within the thick films when exposed to atomic oxygen. The results indicate that the sensors' total resistance increases linearly with time when they are exposed to a constant flux of atomic oxygen, and that the sensors can be regenerated by heating.Index Terms-Atomic Oxygen, Space Environment, Thick film sensors, Zinc Oxide. I. INTRODUCTIONAtomic oxygen (AO) is the main atmospheric constituent in Low Earth Orbit (LEO) at altitudes between 200-1000 km. Atomic oxygen is formed by the photo-dissociation of molecular oxygen by solar ultra-violet (UV) radiation [1]; at these altitudes the probability of recombination is low due to the low atmospheric density and hence the AO is a stable species. Despite its low density it is well known [2] that AO causes high levels of damage over time to many spacecraft materials, particularly those located on forward-facing (ram direction) surfaces. For example, silver electrical contacts are readily oxidised and become non-conducting whilst polymer thermal protection blankets may be eroded, causing their optical properties (emissivity and absorptivity) to change and thus affecting their performance. In both cases the damage processes are enhanced by the high collision energy (approx. 5 eV) of the AO. The AO flux (usually expressed as atoms cm -2 s -1 ) is highly variable, depending primarily on altitude and level of solar activity [1].As an example, for the International Space Station (ISS), residing in a roughly 330 km circular orbit, a typical AO flux J.C. Valer was a doctoral student at the University of Southampton. His contact details are:1 Rowleys Mill,

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Section: DC Resistance Experimentssupporting

confidence: 72%

Section: Discussionmentioning

confidence: 99%

Section: DC Resistance Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Development of a Reusable Atomic Oxygen Sensor Using Zinc Oxide Thick Films

et al. 2013

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“…2) For the category, oxide semiconductors such as ZnO, 3),4) TiO2, 5) V2O5-TiO2, 6) WO3, 7) Gd2O3, 8)-10) and SrTiO3 11),12) have been used. The merit of these semiconductor-type oxygen sensors is a wide-range operation temperature from room temperature to around 1000°C.…”

Section: Introductionmentioning

confidence: 99%

Doping effect of Dy on leakage current and oxygen sensing property of SrTiO3 thin film prepared by PLD

Wakiya

Kimura

Sakamoto

et al. 2009

J. Ceram. Soc. Japan

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Polycrystalline Dy-doped SrTiO3 thin films deposited by pulsed laser deposition (PLD) on CeO2-buffered yttria-stabilized zirconia (YSZ) single crystal substrates showed oxygen sensing characteristics at room temperature. The oxygen gas sensing characteristics depended on the amount of Dy-doping, and 1.5 mol% Dy-doping was most effective. The oxygen gas sensing characteristics were closely related to leakage current characteristics of Dy-doped SrTiO3 thin film deposited on ZnIn2O4/YSZ/ Si(001) substrates. The suppression of leakage current by Dy-doping suggests that Ti 4+ is substituted by Dy 3+ , and the Dy 3+ acts as an acceptor. Further doping of Dy 3+ brought about the increase of the leakage current, and it lowered the oxygen gas sensitivity.

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