Effect of Cd dopant on structural, optical and CO2 gas sensing properties of ZnO thin film sensors fabricated by chemical bath deposition method

Altun, Büşra; Er, İrmak Karaduman; Çağırtekin, Ali Orkun; Ajjaq, Ahmad; Sarf, Fatma; Acar, Selim

doi:10.1007/s00339-021-04843-9

Cited by 25 publications

(10 citation statements)

References 67 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In addition, it has been observed that Ti doping also impacts the structural parameters of ZnO, mainly the average crystallite size ( D ), dislocation density (δ), lattice parameters ( a = b , c ), and value of strain (ε) summarized in Table . D and δ are calculated by the following equations where λ is the X-ray wavelength (1.5406 Å), θ is the diffraction angle, and β is the full width at half maximum (FWHM) of the most intense ZnO (002) peak. The interplanar distance “ d ” values of the films are determined by the ZnO wurtzite structure relation identified by where h , k , and l are the Miller indices of the appropriate diffraction plane.…”

Section: Resultsmentioning

confidence: 99%

Quick NO Gas Sensing by Ti-Doped Flower–Rod-like ZnO Structures Synthesized by the SILAR Method

Soltabayev

Yergaliuly

Ajjaq

et al. 2022

ACS Appl. Mater. Interfaces

Self Cite

View full text Add to dashboard Cite

In this study, Ti-doped ZnO films with flower−rod-like nanostructures were synthesized by the successive ionic layer adsorption and reaction (SILAR) method for enhanced NO gas-sensing applications. The stoichiometric ratio of Ti in the host ZnO lattice was confirmed by atomic absorption and energy-dispersive X-ray spectroscopies. All of the synthesized films exhibited a pure wurtzite hexagonal structure that seemed to deteriorate at high Ti doping contents as was manifested by the measured X-ray diffraction patterns. Scanning electron microscopy images of ZnO revealed the coexistence of porous flower-and rod-like structures, which became finer, denser, and more compact with Ti doping. By UV−vis measurements, the transmittance of the synthesized pure ZnO thin film in the visible region (∼75%) increased by about 10% with Ti doping, and the energy band gap seemed to decrease up to some limit of Ti content. Among the fabricated sensors (based on pure ZnO, 1% Ti-doped, 3% Ti-doped, and 5% Ti-doped ZnO films), the best sensing performance was observed for the 1% Ti-doped ZnO film. At first, this was associated with its high density of oxygen vacancies present on the surface of the film and ionized oxygen vacancies present in the ZnO lattice (confirmed, respectively, by X-ray photoelectron and photoluminescence spectroscopies). Nonetheless, this may also be due to its increased crystallinity (confirmed by X-ray diffraction and photoluminescence spectroscopy), high area-to-volume ratio (confirmed by scanning electron microscopy images), high specific surface area (confirmed by Brunauer−Emmett−Teller measurements) as well as high mobility and carrier concentration (confirmed by Hall measurements). The sensor was highly selective to NO gas and showed notable stability as well as very short response and recovery times, which makes it eligible for the early detection of any indoor or outdoor NO gas leakages.

show abstract

Section: Resultsmentioning

confidence: 99%

Quick NO Gas Sensing by Ti-Doped Flower–Rod-like ZnO Structures Synthesized by the SILAR Method

Soltabayev

Yergaliuly

Ajjaq

et al. 2022

ACS Appl. Mater. Interfaces

Self Cite

View full text Add to dashboard Cite

show abstract

“…However, the desired hydrothermal growth of ZnO structure over the SILAR-deposited CuO layer was not properly achieved at pH < 11.0 and pH > 11.2 and so only properly formed ZnO/CuO composite structures (at pH = 11.0 and pH = 11.2) were taken into consideration. The mean crystallite size (D) of the synthesized structures was estimated based on the detected diffraction peaks using Scherrer equation [27];…”

Section: Role Of Ph In the Chemical Synthesis Of Zno/cuo Heterostruct...mentioning

confidence: 99%

Critical effect of reaction pH on the microstructural, optical and electrical behavior of ZnO/CuO hetero-structured nanocomposite films

Ajjaq²,

Ateş³

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

CuO nanocomposite films and ZnO/CuO nano-heterostructures were synthesized by a series of chemical reactions at different pH values based on the hydrothermal and SILAR (successive ionic layer adsorption and reaction) methods. The ultimate purpose of this work is to explore the impacts of solution pH value and ZnO-based heterostructure on the structural, optical and electrical features of CuO films using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), transmittance spectrum, current-voltage (I-V) measurements and capacitance-conductance (C-G) measurements in 300–600 K temperature range and 20 Hz–1.5 MHz frequency range. XRD analysis revealed that the crystallite size and strain lattice parameters decrease with the increase in pH value without affecting the crystalline structure of the synthesized films. SEM images revealed the regular growth of ZnO structure without any deterioration in the CuO substrate layer where an increase in the thickness of the formed rods was observed with the increase in reaction pH value. Transmittance dropped greatly with the formation of heterojunction from about 40% (for CuO) to about 1% (for ZnO/CuO) in the visible range followed by a crystallite size-induced change in bandgap from 2.29 eV to 2.32 eV (for CuO) and from 2.03 eV to 2.11 eV (for ZnO/CuO). The increase in pH from 11.0 to 11.2 increased the room-temperature resistance of ZnO/CuO composites from 377 MΩ to 474 MΩ, the ideality factor from 4.41 to 4.68 and the barrier height from 0.74 eV to 0.83 eV. It can be deduced that reaction pH value is an important synthesis parameter that can tune the structural, morphological, optical and electrical properties of ZnO/CuO nanocomposite films for advanced industrial or technological implementations by controlling the nucleation and crystal growth rates during chemical synthesis processes.

show abstract

“…The gas sensing mechanism can occur as two main reactions on the MOS sensor surface. In the first reaction, oxygen molecules in the air are chemically adsorbed on the sensor surface and the oxygen molecules transfer electrons in the conduction band towards it [70]. As a result of this transfer, oxygen molecules easily attach to the sensor surface and form an electron consumption region on the surface [70].…”

Section: H 2 Gas Sensing Propertiesmentioning

confidence: 99%

“…In the first reaction, oxygen molecules in the air are chemically adsorbed on the sensor surface and the oxygen molecules transfer electrons in the conduction band towards it [70]. As a result of this transfer, oxygen molecules easily attach to the sensor surface and form an electron consumption region on the surface [70]. The second reaction takes place between the target gas and the oxygen molecules chemically adsorbed to the surface.…”

Section: H 2 Gas Sensing Propertiesmentioning

confidence: 99%

Substrate critical effect on the structural and H₂Gas sensing characteristics of solution-processed Zn_0.075Cu_0.025O films

Özütok

Yakar

et al. 2021

Mater. Res. Express

Self Cite

View full text Add to dashboard Cite

In this study, we report the synthesis of Zn0.075Cu0.025O films by chemical bath deposition to determine the effect of substrate (glass slide or ZnO seed layer) on the structural and H2 gas sensing properties of the produced films. The crystal phase, structural topography, surface morphology and functional groups of the as-synthesized films as well as H2 gas sensing properties were investigated. Although both films have a hexagonal wurtzite structure, ZnO seed layer-based Zn0.075Cu0.025O film is more crystalline than glass slide-based Zn0.075Cu0.025O films. ZnO seed layer-based Zn0.075Cu0.025O films exhibited much more nanorod and less nanosphere forms compared to glass slide-based Zn0.075Cu0.025O films. EDX analysis and Raman spectra of both samples confirmed the presence of defects in Cu:ZnO samples. ZnO seed layer-based sensors showed higher response (140%) and lower operating temperature (80°C) compared to glass slide-based sensors (87% response and 140°C operating temperature). The most important thing to note here is that the fabricated sensors exhibited high response at room temperature. The responses at room temperature was found as 46% and 23% for the ZnO seed layer-based and glass slide-based sensors, respectively. Sensors operating at room temperature are especially important for commercial applications.

show abstract

Effect of Cd dopant on structural, optical and CO2 gas sensing properties of ZnO thin film sensors fabricated by chemical bath deposition method

Cited by 25 publications

References 67 publications

Quick NO Gas Sensing by Ti-Doped Flower–Rod-like ZnO Structures Synthesized by the SILAR Method

Quick NO Gas Sensing by Ti-Doped Flower–Rod-like ZnO Structures Synthesized by the SILAR Method

Critical effect of reaction pH on the microstructural, optical and electrical behavior of ZnO/CuO hetero-structured nanocomposite films

Substrate critical effect on the structural and H₂Gas sensing characteristics of solution-processed Zn_0.075Cu_0.025O films

Contact Info

Product

Resources

About

Effect of Cd dopant on structural, optical and CO2 gas sensing properties of ZnO thin film sensors fabricated by chemical bath deposition method

Cited by 25 publications

References 67 publications

Quick NO Gas Sensing by Ti-Doped Flower–Rod-like ZnO Structures Synthesized by the SILAR Method

Quick NO Gas Sensing by Ti-Doped Flower–Rod-like ZnO Structures Synthesized by the SILAR Method

Critical effect of reaction pH on the microstructural, optical and electrical behavior of ZnO/CuO hetero-structured nanocomposite films

Substrate critical effect on the structural and H2Gas sensing characteristics of solution-processed Zn0.075Cu0.025O films

Contact Info

Product

Resources

About

Substrate critical effect on the structural and H₂Gas sensing characteristics of solution-processed Zn_0.075Cu_0.025O films