Room temperature fabrication and post-annealing treatment of amorphous Ga2O3 photodetectors for deep-ultraviolet light detection

Tungsten trioxide (WO3) is well-known as one of the most promising chromogenic compounds. It has a drastic change of coloration induced from different external stimuli and so its applications are developed as gas sensors, electrochromic panels or photochromic sensors. This paper focuses on the photochromic properties of nanoWO3, with tunable composition (with tunable oxygen sub-stoichiometry). Three reference samples with yellow, blue and black colors were prepared from polyol synthesis followed by post annealing under air, none post-annealing treatment, or a post-annealing under argon atmosphere. These three samples differ in terms of crystallographic structure (cubic system versus monoclinic system), oxygen vacancy concentration, electronic band diagram with occurrence of free or trapped electrons and their photochromic behavior. Constituting one main finding, it is shown that the photochromic behavior is highly dependent on the compound’s composition/color. Rapid and important change of coloration under UV (ultraviolet) irradiation was evidenced especially on the blue compound, i.e., the photochromic coloring efficiency of this compound in terms of contrast between bleached and colored phase, as the kinetic aspect is high. The photochromism is reversible in a few hours. This hence opens a new window for the use of tungsten oxide as smart photochromic compounds.

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Photoluminescence of Zinc Oxide Nanowires: The Effect of Surface Band Bending

ISRN Condensed Matter Physics ◽

10.5402/2012/950354 ◽

2012 ◽

Vol 2012 ◽

pp. 1-6 ◽

Cited By ~ 23

Author(s):

Dake Wang ◽

Nicholas Reynolds

Keyword(s):

Zinc Oxide ◽

Vacancy Concentration ◽

Annealing Treatment ◽

Oxygen Vacancy Concentration ◽

Zinc Oxide Nanowires ◽

Surface Band ◽

Band Bending ◽

Oxide Nanowires ◽

Visible Luminescence ◽

Thermal Annealing Treatment

The photoluminescence of zinc oxide nanowires was investigated via the thermal annealing treatment in oxygen-rich and oxygen-poor conditions. Dramatic changes in the relative intensity of the ultraviolet and the green visible luminescence were observed following different annealing treatments. The changes in photoluminescence bear little correlation to the changes in the oxygen-to-zinc ratios that were revealed using Raman scattering and other characterization techniques. The chemisorption of oxygen and the subsequent surface band bending, instead of the oxygen vacancy concentration, are shown to be the mechanism that determines the observed changes in photoluminescence.

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Facile and cost-effective synthesis of CNT@MCo2O4 (M = Ni, Mn, Cu, Zn) core–shell hybrid nanostructures for organic dye removal

RSC Advances ◽

10.1039/c5ra14748d ◽

2015 ◽

Vol 5 (97) ◽

pp. 79765-79773 ◽

Cited By ~ 15

Author(s):

Haizhen Li ◽

Zebin Sun ◽

Yaxi Tian ◽

Guijia Cui ◽

Shiqiang Yan

Keyword(s):

Room Temperature ◽

Dye Removal ◽

Annealing Treatment ◽

Cost Effective ◽

Organic Dye ◽

Hybrid Nanostructures ◽

Deposition Method ◽

Post Annealing ◽

Simple Chemical ◽

Effective Synthesis

This study presents four hybrid materials of CNT@MCo2O4 (M = Ni, Mn, Cu, Zn) which were prepared via a simple chemical bath deposition method at room temperature followed by a post-annealing treatment.

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High performances room temperature NO2 gas sensor based on ZnO nanoparticles with oxygen vacancies prepared by auto combustion method

10.21203/rs.3.rs-286205/v1 ◽

2021 ◽

Author(s):

Majdi Benamara ◽

Hassen Dahman ◽

Jalel Massoudi ◽

Essebti Dhahri ◽

Lassaad El Mir ◽

...

Keyword(s):

Room Temperature ◽

Oxygen Vacancies ◽

Optical Measurement ◽

Vacancy Concentration ◽

Combustion Method ◽

Visible Range ◽

Light Illumination ◽

Oxygen Vacancy Concentration ◽

Pure Zinc ◽

Auto Combustion

Abstract Pure zinc oxide was prepared by an auto-combustion method and oxygen vacancies were created by means of a thermally activated process as it is based on a vacuum treatment. XRD, XPS and SEM characterizations were used to determine the structure and morphology of pure and treated ZnO1 − X with x equal to 0, 0.05 and 0.10. Optical measurement was investigated in the UV-Visible range and indicated that oxygen vacancies enhance absorption in the visible range. Gas sensors were prepared by spraying the solution of ZnO1 − X nanoparticles on alumina substrates with pre-deposited gold interdigitated electrodes. The fabricated sensors exhibited exceptional sensing responses to 0.5 ppm of NO2 at room temperature and under white light illumination. The sensing tests outline an enhancement in sensors performances due to the presence of oxygen vacancies. The best response was 76, with 1.5 min and 2.7 min as response and recovery times respectively, obtained with sensor based on ZnO0.90 nanoparticles having the higher oxygen vacancy concentration, confirmed by XPS measurements and the lowest grain size and higher absorption in the visible range.

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Detection of a high photoresponse at zero bias from a highly conducting ZnO:Ga based UV photodetector

RSC Advances ◽

10.1039/c5ra13921j ◽

2015 ◽

Vol 5 (104) ◽

pp. 85523-85529 ◽

Cited By ~ 17

Author(s):

Pankaj Sharma ◽

Rohit Singh ◽

Vishnu Awasthi ◽

Sushil K. Pandey ◽

Vivek Garg ◽

...

Keyword(s):

Quantum Efficiency ◽

External Quantum Efficiency ◽

Room Temperature ◽

Metal Structure ◽

Zero Bias ◽

Uv Photodetector ◽

Metal Semiconductor Metal ◽

Doped Zno ◽

Ultraviolet Photodetectors

Ga-doped ZnO based ultraviolet photodetectors (PDs) were fabricated with a metal–semiconductor–metal structure. The room-temperature operable PDs had 58 mA W−1 responsivity at zero bias with internal and external quantum efficiency values of ∼22.5 and 37.4%.

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Intrinsic doping limit and defect-assisted luminescence in Cs4PbBr6

10.26434/chemrxiv.7629467.v3 ◽

2019 ◽

Author(s):

Young-Kwang Jung ◽

Joaquin Calbo ◽

Ji-Sang Park ◽

Lucy D. Wahlley ◽

Sunghyun Kim ◽

...

Keyword(s):

First Principles ◽

Room Temperature ◽

Stokes Shift ◽

Green Luminescence ◽

Counter Ions ◽

Self Consistent ◽

Deep Ultraviolet ◽

Halide Perovskite ◽

Related Compounds ◽

Level Analysis

Cs4PbBr6 is a member of the halide perovskite family that is built from isolated (zero-dimensional) PbBr64- octahedra with Cs+ counter ions. The material exhibits anomalous optoelectronic properties: optical absorption and weak emission in the deep ultraviolet (310 - 375 nm) with efficient luminescence in the green region (~ 540 nm). Several hypotheses have been proposed to explain the giant Stokes shift including: (i) phase impurities; (ii) self-trapped exciton; (iii) defect emission. We explore, using first-principles theory and self-consistent Fermi level analysis, the unusual defect chemistry and physics of Cs4PbBr6. We find a heavily compensated system where the room-temperature carrier concentrations (< 109 cm-3) are more than one million times lower than the defect concentrations. We show that the low-energy Br-on-Cs antisite results in the formation of a polybromide (Br3) species that can exist in a range of charge states. We further demonstrate from excited-state calculations that tribromide moieties are photoresponsive and can contribute to the observed green luminescence. Photoactivity of polyhalide molecules is expected to be present in other halide perovskite-related compounds where they can influence light absorption and emission.

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Intrinsic doping limit and defect-assisted luminescence in Cs4PbBr6

10.26434/chemrxiv.7629467 ◽

2019 ◽

Cited By ~ 1

Author(s):

Young-Kwang Jung ◽

Joaquin Calbo ◽

Ji-Sang Park ◽

Lucy D. Wahlley ◽

Sunghyun Kim ◽

...

Keyword(s):

First Principles ◽

Room Temperature ◽

Stokes Shift ◽

Green Luminescence ◽

Counter Ions ◽

Self Consistent ◽

Deep Ultraviolet ◽

Halide Perovskite ◽

Related Compounds ◽

Level Analysis

Cs4PbBr6 is a member of the halide perovskite family that is built from isolated (zero-dimensional) PbBr64- octahedra with Cs+ counter ions. The material exhibits anomalous optoelectronic properties: optical absorption and weak emission in the deep ultraviolet (310 - 375 nm) with efficient luminescence in the green region (~ 540 nm). Several hypotheses have been proposed to explain the giant Stokes shift including: (i) phase impurities; (ii) self-trapped exciton; (iii) defect emission. We explore, using first-principles theory and self-consistent Fermi level analysis, the unusual defect chemistry and physics of Cs4PbBr6. We find a heavily compensated system where the room-temperature carrier concentrations (< 109 cm-3) are more than one million times lower than the defect concentrations. We show that the low-energy Br-on-Cs antisite results in the formation of a polybromide (Br3) species that can exist in a range of charge states. We further demonstrate from excited-state calculations that tribromide moieties are photoresponsive and can contribute to the observed green luminescence. Photoactivity of polyhalide molecules is expected to be present in other halide perovskite-related compounds where they can influence light absorption and emission.

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Facile Green, Room-Temperature Synthesis of Gold Nanoparticles Using Combretum erythrophyllum Leaf Extract: Antibacterial and Cell Viability Studies against Normal and Cancerous Cells

Antibiotics ◽

10.3390/antibiotics10080893 ◽

2021 ◽

Vol 10 (8) ◽

pp. 893

Author(s):

Olufunto T. Fanoro ◽

Sundararajan Parani ◽

Rodney Maluleke ◽

Thabang C. Lebepe ◽

Jose R. Varghese ◽

...

Keyword(s):

Gold Nanoparticles ◽

Cell Viability ◽

Leaf Extract ◽

Room Temperature ◽

Klebsiella Oxytoca ◽

Cost Effective ◽

Average Diameter ◽

Antibacterial Activities ◽

Inhibition Concentration ◽

First Time

We herein report a facile, green, cost-effective, plant-mediated synthesis of gold nanoparticles (AuNPs) for the first time using Combretum erythrophyllum (CE) plant leaves. The synthesis was conducted at room temperature using CE leaf extract serving as a reducing and capping agent. The as-synthesized AuNPs were found to be crystalline, well dispersed, and spherical in shape with an average diameter of 13.20 nm and an excellent stability of over 60 days. The AuNPs showed broad-spectrum antibacterial activities against both pathogenic Gram-positive (Staphylococcus epidermidis (ATCC14990), Staphylococcus aureus (ATCC 25923), Mycobacterium smegmatis (MC 215)) and Gram-negative bacteria (Proteus mirabilis (ATCC 7002), Escherichia coli (ATCC 25922), Klebsiella pneumoniae (ATCC 13822), Klebsiella oxytoca (ATCC 8724)), with a minimum inhibition concentration of 62.5 µg/mL. In addition, the as-synthesized AuNPs were highly stable with exceptional cell viability towards normal cells (BHK- 21) and cancerous cancer cell lines (cervical and lung cancer).

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