Amorphous Selenium and Nanostructures

Tanaka, Keiji

doi:10.1007/978-3-319-93728-1_19

Cited by 13 publications

(6 citation statements)

References 417 publications

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“…In this paper, we explore an amorphous selenium (aSe) based detector. Defined as a non-crystalline solid which lacks the long range periodicity in its atomic structure, amorphous selenium has the remarkable semiconductor property of high photoconductivity, can be deposited uniformly over a large areas and has charge transport which is non-dispersive over typical device drift times [33]. An abundance of research into aSe based direct conversion active matrix flat panel imagers (AMFPI) [34] and digital breast tomosynthesis [35] has taken place in the field of X-ray imaging.…”

Section: Introductionmentioning

confidence: 99%

Development of a novel, windowless, amorphous selenium based photodetector for use in liquid noble detectors

et al. 2023

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Detection of the vacuum ultraviolet (VUV) scintillation light produced by liquid noble elements is a central challenge in order to fully exploit the available timing, topological, and calorimetric information in detectors leveraging these media. In this paper, we characterize a novel, windowless amorphous selenium based photodetector with direct sensitivity to VUV light. We present here the manufacturing and experimental setup used to operate this detector at low transport electric fields (2.7–5.2 V/μm) and across a wide range of temperatures (77 K–290 K). This work shows that the first proof-of-principle windowless amorphous selenium device is robust under cryogenic conditions, responsive to VUV light at cryogenic temperatures, and preserves argon purity. These findings motivate a continued exploration of amorphous selenium devices for simultaneous detection of scintillation light and ionization charge in noble element detectors.

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Section: Introductionmentioning

confidence: 99%

Development of a novel, windowless, amorphous selenium based photodetector for use in liquid noble detectors

et al. 2023

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“…Current interest lies not only in the use of a-Se but also in polycrystalline Se both for existing technologies and for novel devices which may underpin next generation systems [13][14][15][16][17][18][19]. The properties of a-Se have been widely reviewed in the literature and most recently by Tanaka [20]. Extending the functionality of these materials will depend heavily on how such material properties can be controlled in device structures.…”

Section: Introductionmentioning

confidence: 99%

Frequency- and time-resolved photocurrents in vacuum-deposited stabilised a-Se films: the role of valence alternation defects

Jacobs

Belev

Brookfield

et al. 2020

J Mater Sci: Mater Electron

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Stabilised amorphous selenium (a-Se) is currently used in the majority of direct conversion mammographic X-ray imaging detectors due to its X-ray photoconductivity and its ability to be uniformly deposited over large area TFT substrates by conventional vacuum deposition. We report experimental results on photocurrent spectroscopy (frequency-resolved spectroscopy (FRS) and single-time transients), on vacuum-deposited a-Se films. We show that all measured photocurrents depend critically on the relative time spent by the material in the light and in the dark. We identify that the observed pronounced variation in optical response depends on the density of trapped (optically injected) charge within 200 nm of the surface and show that it is the ratio of dark and light exposure time that controls the density of such charge. Our data confirm that the localised charge radically influences the photocurrent transient shape due to the effective screening of the applied field within 200 nm of the surface. The field modification occurs over the optical extinction depth and changes both the photogeneration process and the drift of carriers. Many aspects of our data carry the signature of known properties of valence alternation pair (VAP) defects, which control many properties of a-Se. Modelling in the time domain shows that light generation of VAPs followed by optically triggered VAP defect conversion can lead to near-surface charge imbalance, demonstrating that VAP defects can account for the unusual optical response. The stabilised a-Se films were deposited above the glass transition temperature of the alloy with composition a-Se:0.3% As doped with ppm Cl. Electron paramagnetic resonance measurements at temperatures down to 5 K did not detect any spin active defects, even under photoexcitation above band gap.

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“…unique atomic configurations and relevant properties [1,2], as well as the wide technological applications in diverse industrial fields, including xerography, photovoltaics, and xray detectors [3]. As one of the most thoroughly studied chalcogens in the amorphous state, a-Se stands as a typical example of a monoatomic polymeric material [4,5].…”

Section: Introductionmentioning

confidence: 99%

Early crystallization of amorphous selenium under high pressure studied by synchrotron XRD method

Yuan

Wang

Liu

et al. 2023

J. Phys.: Condens. Matter

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The amorphous selenium (a-Se) was studied via X-ray diffraction (XRD) under pressures ranging from ambient pressure up to 30 GPa at room temperature to study its high-pressure behavior. Two compressional experiments on a-Se samples, with and without heat treatment, respectively, were conducted. Contrary to the previous reports that a-Se crystallized abruptly at around 12 GPa, in this work we report an early partially crystallized state at 4.9 GPa before completing the crystallization at around 9.5 GPabased on in-situ high pressure XRD measurements on the a-Se with 70 ℃ heat treatment. In comparison, crystallization pressure on another a-Se sample without thermal treatment history was observed to be 12.7 GPa, consistent with the previously reported crystallization pressure. Thus, it is proposed in this work that prior heat treatment of a-Se can result in an earlier crystallization under high pressure, which helps to understand the possible mechanism caused by the previous controversial reports on pressure induced crystallization behavior in a-Se.

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Amorphous Selenium and Nanostructures

Cited by 13 publications

References 417 publications

Development of a novel, windowless, amorphous selenium based photodetector for use in liquid noble detectors

Development of a novel, windowless, amorphous selenium based photodetector for use in liquid noble detectors

Frequency- and time-resolved photocurrents in vacuum-deposited stabilised a-Se films: the role of valence alternation defects

Early crystallization of amorphous selenium under high pressure studied by synchrotron XRD method

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