Investigations on the Photoprotection Ability of TiO2 Coated on Copper

A TiO2 coating when directly applied on copper plate showed an instantaneous ptype behavior, i.e. ennoblement of electrode potential on ultraviolet (UV) illumination though a copper plate when galvanically coupled to an ITO glass coated with TiO2 showed immediate lowering of electrode potential (‘n’-type effect) on illumination under deaerated conditions. The instantaneous p-type effect in the former case was attributed to the presence of a copper oxide layer present between the copper plate and the TiO2 coating. However, a prolonged exposure of the TiO2 coated copper plate showed an n-type effect under illumination after nearly 24 h, following which the electrode potential appeared stable and highly negative. This observation indicated that the photogenerated electrons in TiO2 are capable of reducing the copper oxide layer to ultimately realize the n-type effect of TiO2. The n-type effect could not be observed in aerated electrolyte solutions. The effect of different conditions in the ambience on the photoeffect of copper coated TiO2 will be discussed.

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Chromatic Change in Copper Oxide Layers Irradiated with Low Energy Ions

10.20944/preprints202102.0113.v1 ◽

2021 ◽

Author(s):

Takuya Kobayashi ◽

Fumitaka Nishiyama ◽

Katsumi Takahiro

Keyword(s):

Copper Oxide ◽

Oxide Layer ◽

Significant Loss ◽

Copper Plate ◽

Low Energy ◽

Nuclear Reaction Analysis ◽

Photoemission Spectrum ◽

Satellite Line ◽

Copper Valence ◽

Low Energy Ions

The color of a thin copper oxide layer formed on a copper plate was transformed from reddish-brown into blue-purple by irradiation with 5 keV Ar+ ions to a fluence as low as 1 1015 Ar+ cm–2. In the unirradiated copper oxide layer, the copper valence state of Cu2+ as well as Cu+ and/or Cu0 was included as indicated by the presence of a shake-up satellite line in a photoemission spectrum. While for the irradiated one, the satellite line decreased in intensity, indicating that irradiation resulted in the reduction from Cu2+ to Cu+ and/or Cu0. Furthermore, nuclear reaction analysis using a 16O(d, p)17O reaction with 0.85 MeV deuterons revealed a significant loss of oxygen (51015 O atoms cm–2) in the irradiated layer. Thus, the chromatic change observed in the present work originated in the irradiation-induced reduction of a copper oxide.

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The theory of crystal rectifiers

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1939.0051 ◽

1939 ◽

Vol 171 (944) ◽

pp. 27-38 ◽

Cited By ~ 321

Keyword(s):

Copper Oxide ◽

Oxide Layer ◽

Cuprous Oxide ◽

Copper Plate ◽

Significant Part ◽

Lead Plate

It has long been known that the contact between a metal and a semiconductor has a resistance which varies, in many cases considerably, with the direction of the current. A well-known example is the copper-cuprous oxide rectifier, which consists of a copper plate on which a layer of cuprous oxide has been formed, the oxide being in contact with a lead plate. It is the purpose of this paper to criticize existing theories of this effect and to suggest a new one. In any crystal rectifier we have two contacts to consider; for instance, in the copper-oxide rectifier there is the contact between the copper and the oxide, and that between the oxide and the lead. We may say at once that a condition for rectification is that at least one of these contacts shall have a resistance which is not small compared with the resistance of the oxide layer; for any theory will give, in the limit of small voltages across the contact, equal resistances in both directions; it is necessary that a significant part of the fall in potential in the rectifier should occur at the contact.

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Chromatic Change in Copper Oxide Layers Irradiated with Low Energy Ions

Quantum Beam Science ◽

10.3390/qubs5010007 ◽

2021 ◽

Vol 5 (1) ◽

pp. 7

Author(s):

Takuya Kobayashi ◽

Fumitaka Nishiyama ◽

Katsumi Takahiro

Keyword(s):

Copper Oxide ◽

Oxide Layer ◽

Significant Loss ◽

Copper Plate ◽

Nuclear Reaction Analysis ◽

Photoemission Spectrum ◽

Satellite Line ◽

Copper Valence ◽

Low Energy Ions ◽

Dark Blue

The color of a thin copper oxide layer formed on a copper plate was transformed from reddish-brown into dark blue-purple by irradiation with 5 keV Ar+ ions to a fluence as low as 1 × 1015 Ar+ cm−2. In the unirradiated copper oxide layer, the copper valence state of Cu2+ and Cu+ and/or Cu0 was included as indicated by the presence of a shake-up satellite line in a photoemission spectrum. While for the irradiated one, the satellite line decreased in intensity, indicating that irradiation resulted in the reduction from Cu2+ to Cu+ and/or Cu0. Furthermore, nuclear reaction analysis using a 16O(d, p)17O reaction with 0.85 MeV deuterons revealed a significant loss of oxygen (5 × 1015 O atoms cm−2) in the irradiated layer. Thus, the chromatic change observed in the present work originated in the irradiation-induced reduction of a copper oxide.

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Fabrication and Characterization of Heterojunction Based on a Copper Oxide Layer

10.1109/khpiweek53812.2021.9569979 ◽

2021 ◽

Author(s):

Oleksii Diachenko ◽

Anatoliy Opanasyuk ◽

Tetiana Protasova ◽

Patrik Novak ◽

Jaroslav Kovac

Keyword(s):

Copper Oxide ◽

Oxide Layer ◽

Fabrication And Characterization

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Optimizing copper oxide layer on zinc oxide via two-step electrodeposition for better photocatalytic performance in photoelectrochemical cells

Applied Surface Science ◽

10.1016/j.apsusc.2019.02.187 ◽

2019 ◽

Vol 479 ◽

pp. 1110-1117 ◽

Cited By ~ 8

Author(s):

Fatih Tezcan ◽

Asad Mahmood ◽

Gulfeza Kardaş

Keyword(s):

Zinc Oxide ◽

Copper Oxide ◽

Oxide Layer ◽

Photocatalytic Performance ◽

Photoelectrochemical Cells

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Copper Doped ZnO Thin Film for Ultraviolet Photodetector with Enhanced Photosensitivity

MRS Proceedings ◽

10.1557/opl.2012.1742 ◽

2013 ◽

Vol 1494 ◽

pp. 43-49 ◽

Cited By ~ 1

Author(s):

Akshta Rajan ◽

Kashima Arora ◽

Harish Kumar Yadav ◽

Vinay Gupta ◽

Monika Tomar

Keyword(s):

Thin Film ◽

Sol Gel ◽

High Porosity ◽

Zno Thin Film ◽

X Ray Diffraction ◽

Uv Photodetector ◽

Response Characteristics ◽

Uv Illumination ◽

Photogenerated Electrons ◽

Doped Zno

ABSTRACTUltraviolet photoconductivity in Copper doped ZnO (Cu:ZnO) thin films synthesized by sol-gel technique is investigated. Response characteristics of Pure ZnO thin film and Cu:ZnO thin film UV photodetector with 1.3 at. wt % Cu doping biased at 5 V for UV radiation of λ = 365 nm and intensity = 24 µwatt/cm2 has been studied. Cu:ZnO UV photodetector is found to exhibit a high photocoductive gain (K = 1.5×104) with fast recovery (T90% = 23s) in comparison to pure ZnO thin film based photodetector (K = 4.9×101 and T90% = 41s). Cu2+ ions have been substituted in ZnO lattice which has been confirmed by X-ray diffraction (XRD) and Raman spectroscopy leading to lowering of dark current (Ioff ∼ 1.44 nA). Upon UV illumination, more electron hole pairs are generated in the photodetector due to the high porosity and roughness of the surface of the film which favours adsorption of more oxygen on the surface of the photodetector. The photogenerated holes recombined with the trapped electrons, increasing the concentration of photogenerated electrons in the conduction band enhancing the photocurrent (Ion ∼ 0.02 mA) of the Cu:ZnO photodetector.

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β-Ketoiminato-based copper(ii) complexes as CVD precursors for copper and copper oxide layer formation

Dalton Transactions ◽

10.1039/c8dt01647j ◽

2018 ◽

Vol 47 (30) ◽

pp. 10002-10016 ◽

Cited By ~ 2

Author(s):

Elaheh Pousaneh ◽

Marcus Korb ◽

Volodymyr Dzhagan ◽

Marcus Weber ◽

Julian Noll ◽

...

Keyword(s):

Copper Oxide ◽

Oxide Layer ◽

Layer Formation

A series of mono- and dinuclear Cu(ii)-β-ketoiminato complexes as CVD precursors are discussed.

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Recombination at surface states in GaN

MRS Proceedings ◽

10.1557/proc-680-e5.4 ◽

2001 ◽

Vol 680 ◽

Cited By ~ 3

Author(s):

M. A. Reshchikov ◽

P. Visconti ◽

K. M. Jones ◽

H. Morkoç ◽

C. W. Litton ◽

...

Keyword(s):

Surface States ◽

Depletion Region ◽

Nonradiative Recombination ◽

Etch Pits ◽

Blue Band ◽

Near Surface ◽

Force Microscopy ◽

Uv Illumination ◽

Photogenerated Electrons ◽

Subsequent Exposure

ABSTRACTWe have studied radiative and nonradiative recombination at surface states in GaN, including as-grown samples and those treated with acids or bases. The surface states manifested themselves in two ways: (i) a reversible increase of the photoluminescence (PL) intensity after ultraviolet (UV) illumination in vacuum and (ii) appearance of new PL bands after treatment with acid or base and subsequent exposure to air. It has been established that the GaN surface physi-sorbs species from air (presumably oxygen) which induce surface states acting as nonradiative recombination centers. It has been found that nonradiative recombination of photogenerated carriers via surface states comprises more than 70% of the recombination in some GaN samples. Another type of the surface state, which participates in radiative recombination, has been found in GaN samples with Ga polarity after brief etching of the surface with hot acid or base and subsequent exposure to air. In such samples, a broad PL band emerges in the blue region of the spectrum at low temperatures. The blue band has been attributed to transitions of photogenerated electrons from donors in the near-surface depletion region to the surface states introduced by the above-mentioned procedure. The changes in the GaN surface caused by etching were examined by atomic force microscopy. In some samples the blue band appeared even when no evidence of the layer etching was found except for quite shallow etch pits formed at dislocation sites. The emerging blue band can be related to the surface states formed on the a-planes of etch pits.

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