Mechanism of conductivity degradation of AZO thin film in high humidity ambient

Liu, Yen Shuo; Hsieh, Chih Yi; Wu, Yen‐Ju; Yu, Wei; Lee, Po Ming; Hsieh, Hsiu Ming; Liu, Cheng Yi

doi:10.1016/j.apsusc.2013.04.167

Cited by 24 publications

(16 citation statements)

References 14 publications

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“…In literature, the frequently observed semiconducting oxide conductivity has been often attributed to oxygen vacancies. It was reported that, one oxygen vacancy could bound two electrons as free carriers 36 37 and oxygen vacancies could introduce donor levels between the conduction and valence bands 24 38 , which would result in increased conductivity for semiconducting oxides. At low humidity, the electrons related to the ionization of donor centers (oxygen vacancies) of the present WO 3−x crystals are the effective charge carriers, thus enhancing the conductivity of WO 3−x crystals when the density of oxygen vacancies increases.…”

Section: Materials Composition and Structurementioning

confidence: 99%

Positive impedance humidity sensors via single-component materials

Qian

Peng

Shen

et al. 2016

Sci Rep

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Resistivity-type humidity sensors have been investigated with great interest due to the increasing demands in industry, agriculture and daily life. To date, most of the available humidity sensors have been fabricated based on negative humidity impedance, in which the electrical resistance decreases as the humidity increases, and only several carbon composites have been reported to present positive humidity impedance. However, here we fabricate positive impedance humidity sensors only via single-component WO3−x crystals. The resistance of WO3−x crystal sensors in response to relative humidity could be tuned from a negative to positive one by increasing the compositional x. And it was revealed that the positive humidity impedance was driven by the defects of oxygen vacancy. This result will extend the application field of humidity sensors, because the positive humidity impedance sensors would be more energy-efficient, easier to be miniaturized and electrically safer than their negative counterparts for their lower operation voltages. And we believe that constructing vacancies in semiconducting materials is a universal way to fabricate positive impedance humidity sensors.

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Section: Materials Composition and Structurementioning

confidence: 99%

Positive impedance humidity sensors via single-component materials

Qian

Peng

Shen

et al. 2016

Sci Rep

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“…As a result, the electrical conductivity would increase, because the waterrelated electrolytic conduction mainly functionalizes as a surface mechanism [23]. In literature, it was reported that, oxygen vacancies would bound electrons as free carriers [24,25], and thus they could introduce donor levels between the conduction and valence bands [10,26], which would Journal of Nanomaterials 7 11% Relative humidity 33% Relative humidity 54% Relative humidity 75% Relative humidity 85% Relative humidity 95% Relative humidity 11% Relative humidity 33% Relative humidity 54% Relative humidity 75% Relative humidity 85% Relative humidity 95% Relative humidity result in increased conductivity for semiconducting oxides. For the WO 2.90 and W 19 O 55 devices, the oxygen vacancies induced conduction mechanism would compete with the water-related surface mechanism, which might even become dominating in the transport process at low humidity.…”

Section: Electrical Propertiesmentioning

confidence: 99%

Role of Oxygen Vacancies in the Electrical Properties of WO_3−x Nano/Microrods with Identical Morphology

Shen

Zhao

Wen

et al. 2018

Journal of Nanomaterials

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Tungsten oxide (WO 3−x ) crystalline nano/microrods with identical morphology but different contents of oxygen vacancies were prepared by thermally evaporating fixed amount of WO 3 powder in reductive atmosphere from different amounts of S power at 1150 ∘ C in a vacuum tube furnace, in which both sources were loaded in separate ceramic boat. With increasing amount of S powder, a series of tungsten oxides, WO 3 , WO 2.90 , W 19 O 55 (WO 2.89 ), and W 18 O 49 (WO 2.72 ), could be obtained. And devices were fabricated by screen-printing the obtained WO 3−x crystals on ceramic substrates with Ag-Pd interdigital electrodes. With increasing content of oxygen vacancies, the devices fabricated with WO 3−x crystals present a negative to positive resistance response to relative humidity. Under dry atmosphere, for the devices with increasing , the strong response to light changed from short to long wavelength; under light irradiation, the conducting ability of the devices was enhanced, due to the more efficient separation and transportation of the photogenerated carriers; and under simulated solar irradiation, the photocurrent intensity of the W 18 O 49 device was roughly 8 times, about 500 times, and even 1000 times larger than that of the W 19 O 55 , WO 2.90 , and WO 3 one, respectively. With the versatile optoelectrochemical properties, the obtained WO 3−x crystals have the great potential to prepare various humidity sensors and optoelectrical devices.

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“…In recent years, a development of nanomaterial-based semiconductor caused dynamic progress in fabrication of more advanced electronic systems [ 1 , 2 , 3 ]. Indium-tin oxide (ITO), a heavily doped and highly degenerated n-type semiconductor with high carrier concentration (~10 21 cm −3 ) [ 4 , 5 , 6 ], is one of the most widely used transparent conductive oxides (TCO) due to unique combination of excellent electrical conductivity, optical transparency and good mechanical properties and relatively good chemical stability [ 7 , 8 , 9 ]. Although various new materials, such as tin dioxide (SnO 2 ) [ 10 ], zinc oxide (ZnO) [ 11 , 12 ], indium zinc oxide (IZO) [ 13 ], conductive nano-silver wire [ 14 ], have been applied in industry, ITO is still the main choice for conductive optical [ 15 ].…”

Section: Introductionmentioning

confidence: 99%

High Power Impulse Magnetron Sputtering of In2O3/Sn Cold Sprayed Composite Target

2021

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High Power Impulse Magnetron Sputtering (HiPIMS) was used for deposition of indium tin oxide (ITO) transparent thin films at low substrate temperature. A hybrid-type composite target was self-prepared by low-pressure cold spraying process. Prior to spraying In2O3 and oxidized Sn powders were mixed in a volume ratio of 3:1. Composite In2O3/Sn coating had a mean thickness of 900 µm. HiPIMS process was performed in various mixtures of Ar:O2: (i) 100:0 vol.%, (ii) 90:10 vol.%, (iii) 75:25 vol.%, (iv) 50:50 vol.%, and (v) 0:100 vol.%. Oxygen rich atmosphere was necessary to oxidize tin atoms. Self-design, simple high voltage power switch capable of charging the 20 µF capacitor bank from external high voltage power supply worked as a power supply for an unbalanced magnetron source. ITO thin films with thickness in the range of 30–40 nm were obtained after 300 deposition pulses of 900 V and deposition time of 900 s. The highest transmission of 88% at λ = 550 nm provided 0:100 vol. % Ar:O2 mixture, together with the lowest resistivity of 0.03 Ω·cm.

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Mechanism of conductivity degradation of AZO thin film in high humidity ambient

Cited by 24 publications

References 14 publications

Positive impedance humidity sensors via single-component materials

Positive impedance humidity sensors via single-component materials

Role of Oxygen Vacancies in the Electrical Properties of WO_3−x Nano/Microrods with Identical Morphology

High Power Impulse Magnetron Sputtering of In2O3/Sn Cold Sprayed Composite Target

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Mechanism of conductivity degradation of AZO thin film in high humidity ambient

Cited by 24 publications

References 14 publications

Positive impedance humidity sensors via single-component materials

Positive impedance humidity sensors via single-component materials

Role of Oxygen Vacancies in the Electrical Properties of WO3−x Nano/Microrods with Identical Morphology

High Power Impulse Magnetron Sputtering of In2O3/Sn Cold Sprayed Composite Target

Contact Info

Product

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Role of Oxygen Vacancies in the Electrical Properties of WO_3−x Nano/Microrods with Identical Morphology