Significance of Fatigue in Lead Oxide Vidicon Target

Bigelow, J.E.; Haq, K. E.

doi:10.1063/1.1728546

Cited by 9 publications

(12 citation statements)

References 2 publications

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“…With that assumption we obtained ∆ f H 0 (PbO)=-2.92 eV per Pb-O pair which is in appropriate agreement with the experimental value of ∆ f H 0 (crystal α-PbO)=-2.29 eV [24]. It is known that regardless the deposition techniques used, the PbO layers are not stoichiometric and has deficit of oxygen [8][9][10]. Hence, we consider the Pbrich/O-poor conditions for which the O-poor limit has been assigned to µ * (O) = ∆ f H 0 (PbO) [23] (µ * (O) =-2.92 eV), while Pb-rich limit has been found from relation…”

Section: B the Formation Energy Of The Vacanciessupporting

confidence: 74%

“…As it was mentioned above, in practice thermally grown polycrystalline α-PbO contains large amount of the O vacancies [8][9][10]. Therefore, in this work we consider the formation of the native point defects (i.e.…”

Section: Resultsmentioning

confidence: 99%

“…Thermally deposited PbO has an oxygen deficiency [8][9][10]. Although the effect of the O vacancies on transport in PbO is not clearly understood, it was found that thermal annealing in pure oxygen increases the electrical conductivity that can be attributed to the reduction of the oxygen vacancy concentration [8].…”

Section: Introductionmentioning

confidence: 99%

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Lead monoxide α-PbO: electronic properties and point defect formation

Berashevich

Semeniuk

Rubel

et al. 2013

J. Phys.: Condens. Matter

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The electronic properties of polycrystalline lead oxide consisting of a network of single-crystalline α-PbO platelets and the formation of the native point defects in α-PbO crystal lattice are studied using first principles calculations. The α-PbO lattice consists of coupled layers interaction between which is too low to produce high efficiency interlayer charge transfer. In practice, the polycrystalline nature of α-PbO causes the formation of lattice defects in such a high concentration that defectrelated conductivity becomes the dominant factor in the interlayer charge transition. We found that the formation energy for the O vacancies is low, such vacancies are occupied by two electrons in the zero charge state and tend to initiate the ionization interactions with the Pb vacancies. The vacancies introduce localized states in the band gap which can affect charge transport. The O vacancy forms a defect state at 1.03 eV above the valence band which can act as a deep trap for electrons, while the Pb vacancy forms a shallow trap for holes located just 0.1 eV above the valence band. Charge de-trapping from O vacancies can be accounted for the experimentally found dark current decay in ITO/PbO/Au structures.

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Section: B the Formation Energy Of The Vacanciessupporting

confidence: 74%

Section: Resultsmentioning

confidence: 99%

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Lead monoxide α-PbO: electronic properties and point defect formation

Berashevich

Semeniuk

Rubel

et al. 2013

J. Phys.: Condens. Matter

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“…The grown PbO films are known to consist of two different crystallographic phases of PbO: the seeding layer, several microns thick, is formed by the yellow orthorhombic -PbO, while the bulk of the layer grows predominately as a red tetragonal lead oxide (-PbO), however, -PbO is also present in the bulk [7]. In addition, the grown layers are substoichiometric with a deficit of oxygen [8][9][10]. The latter is due to the low formation energy of oxygen vacancies [10,11] which can act as charge trapping centers -a highly undesirable feature for any detector material.…”

Section: Introductionmentioning

confidence: 99%

Ion-assisted deposition of amorphous PbO layers

et al. 2017

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Lead oxide (PbO) is one of the most promising materials for application in direct conversion medical imaging X-ray detectors. Despite its high potential, conventional polycrystalline PbO layers deposited with the basic thermal evaporation method are not yet mature for practical use in x-ray imaging; indeed, they are highly porous, unstable at ambient conditions, and sub-stoichiometric. In order to combat the above issues with PbO, we advance the basic evaporation process with simultaneous energetic ion bombardment of the growing film. We show that tuning the ion-assisted thermal deposition not only solves the structural problems of poly-PbO, but also enables the growth of a new non-crystalline polymorphic form of the material-amorphous PbO (a-PbO). In contrast to poly-PbO, novel a-PbO layers grown by ion-assisted thermal deposition are stable at ambient conditions. Structural and morphological analysis confirms that a-PbO is stoichiometric and free of detectable voids, which suggests higher bulk X-ray stopping power than porous poly-PbO.

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“…[3][4][5] Since that time, tremendous improvements have been made in the field of x-ray photoconductors, most notably with the photoconductor amorphous selenium ͑a-Se͒. 6 By incorporating these improved x-ray photoconductors into a large area vidicon, it should be possible to produce a device suitable for medical fluoroscopy.…”

Section: Introductionmentioning

confidence: 99%

Feasibility of a large area x‐ray sensitive vidicon for medical fluoroscopy: Signal and noise factors

Luhta

Rowlands

1997

Medical Physics

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A large area x-ray sensitive vidicon is being investigated as an alternative to the x-ray image intensifier and television camera combination for medical fluoroscopy. Signal generation in an x-ray vidicon involves an x-ray photoconductive layer whose surface is scanned by an electron beam. The single x-ray to electron conversion stage of the x-ray vidicon offers a greatly improved modulation transfer function (MTF) over the x-ray image intensifier. This superior MTF allows signal and x-ray quantum noise at high spatial frequencies to be passed to the preamplifier with less attenuation. In cardiac cine applications this would allow quantum noise limited operation at higher spatial frequencies than is possible with the x-ray image intensifier system.

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Significance of Fatigue in Lead Oxide Vidicon Target

Cited by 9 publications

References 2 publications

Lead monoxide α-PbO: electronic properties and point defect formation

Lead monoxide α-PbO: electronic properties and point defect formation

Ion-assisted deposition of amorphous PbO layers

Feasibility of a large area x‐ray sensitive vidicon for medical fluoroscopy: Signal and noise factors

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