scholarly journals Enhanced Ammonia Sensing By Cost-Effective ZnO Thin Films Through Yttrium Doping

2021 ◽  
Author(s):  
K. Ravichandran ◽  
A. Jansi Santhosam ◽  
M. Aldossary Omar ◽  
Mohd Ubaidhulla
Keyword(s):  
Thin Films ◽  
Active Sites ◽  
Oxygen Vacancies ◽  
Gas Sensing ◽  
Spray Pyrolysis Technique ◽  
Hexagonal Wurtzite Structure ◽  
Zno Thin Films ◽  
Composition Analysis ◽  
Response Recovery ◽  
Yttrium Doping

Abstract Yttrium (Y) doped (doping concentration - 0, 1, 3 and 5 wt%) ZnO thin films were deposited using spray pyrolysis technique. The structural, surface morphological, optical and compositional properties were analysed using X-Ray diffraction (XRD), Atomic Force Microscopy (AFM), UV-vis NIR spectrophotmetry (UV), photoluminescence study (PL) and elemental composition analysis. Ammonia vapour sensing properties such as response/recovery, stability and repeatability were studied at room temperature. XRD results confirmed that the prepared samples have hexagonal wurtzite structure. ZnO:Y thin film with 5 wt% yttrium doping exhibits excellent sensing response of 99, fast response/recovery times of 29 s/ 7 s which may be due to the existence of oxygen vacancies in the case of ZnO:Y (5 wt%) film sample confirmed by photoluminescence (PL) study. These oxygen vacancies attract more electrons and thus enhance the gas sensing. In addition, increase in the number of active sites caused by the substitution of Y3+(trivalent) ions into the Zn2+ (divalent) regular sites as confirmed by the observed M-B (Moss-Burstein) effect also causes an enhancement in the gas sensing. Surface roughness, another reason for the enhanced sensitivity, has been confirmed by AFM.

scholarly journals Influence of Annealing on Properties of Spray Deposited ZnO Thin Films

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Kalyani Nadarajah ◽  
Ching Yern Chee ◽  
Chou Yong Tan
Keyword(s):  
Thin Films ◽  
Electrical Resistivity ◽  
Spray Pyrolysis Technique ◽  
Hexagonal Wurtzite Structure ◽  
Ambient Air ◽  
Zno Thin Films ◽  
Visible Range ◽  
X Ray ◽  
Average Grain Size ◽  
Vis Spectroscopy

Zinc Oxide (ZnO) thin films were deposited on glass substrates via the spray pyrolysis technique. The films were subsequently annealed in ambient air from 300°C to 500°C. The morphology and structural properties of the thin films were studied by field emission scanning electron microscope (FESEM), atomic force microscopy (AFM), and X-ray diffractometry (XRD) techniques. Electrical resistivity of the thin films was measured using a data acquisition unit. The optical properties of the films were characterized by UV-vis spectroscopy and photoluminescence (PL) technique. X-ray diffraction data showed that the films were grown in the (002) direction with a hexagonal wurtzite structure. The average grain size ranged from 15 to 27 nm. Increasing annealing temperatures resulted in larger grain sizes and higher crystallinity, with the surface roughness of annealed films being more than twice if compared to unannealed film. The electrical resistivity of the films decreased with the increasing annealing temperature. The UV and visible band emissions were observed in the photoluminescence spectra, due to exciton and defect-related emissions, respectively. The transmission values of the films were as high as 90% within the visible range (400–700 nm).

Reactive sputtered ZnO thin films: Influence of the O2/Ar flow ratio on the oxygen vacancies and paramagnetic active sites

2019 ◽  
Vol 692 ◽  
pp. 137641 ◽  
Author(s):  
Adrián A. Camacho-Berríos ◽  
Víctor M. Pantojas ◽  
Wilfredo Otaño
Keyword(s):  
Thin Films ◽  
Active Sites ◽  
Oxygen Vacancies ◽  
Zno Thin Films ◽  
Flow Ratio

scholarly journals Evaluation of spray pyrolysed In:ZnO nanostructures for CO gas sensing at low concentration

2021 ◽  
Author(s):  
Aninamol Ani ◽  
P. Poornesh ◽  
K. K. Nagaraja ◽  
Gopalkrishna Hegde ◽  
E. Kolesnikov ◽  
...  
Keyword(s):  
Thin Films ◽  
Carbon Monoxide ◽  
Gas Sensing ◽  
Spray Pyrolysis Technique ◽  
High Surface ◽  
High Response ◽  
Zno Thin Films ◽  
Low Concentration ◽  
Xrd Studies ◽  
Co Gas

AbstractHerein, we report the role of indium (In) on the carbon monoxide sensing of ZnO thin films using a low-cost spray pyrolysis technique. The decrease in crystalline size was observed from XRD studies and hexagonal wurtzite structure was confirmed. Photoluminescence and XPS studies proved the presence of various defects in the films. The gas-sensing properties of films toward carbon monoxide (CO) gas indicate that 15 wt% of In in ZnO thin films (IZO) exhibit high response (1.84) to a low concentration of the gas (1 ppm) at 300 °C compared to undoped ZnO (0.53). The observed high response of 15 wt% IZO can be mainly endorsed to the oxygen vacancy defects as observed from the photoluminescence and XPS analysis. Further, the high response is complemented by high surface area and smaller grain size (~ 13.1 nm) with well-defined grain boundaries as evident from SEM analysis as well as XRD studies.

scholarly journals The study of transparent conducting gallium doped ZnO thin films in order to use in solar cells

2018 ◽  
Vol 6 (2) ◽  
pp. 56
Author(s):  
Mojtaba Mahmoudzadeh Pirvahshi
Keyword(s):  
Thin Films ◽  
Spray Pyrolysis Technique ◽  
Hexagonal Wurtzite Structure ◽  
Growth Direction ◽  
Zno Thin Films ◽  
Visible Range ◽  
Chemical Spray Pyrolysis ◽  
Range Data ◽  
Transparent Conducting ◽  
Doped Zno

In this study, transparent conducting Ga-doped ZnO thin films were deposited on glass substrate using chemical spray pyrolysis technique. The effect of Ga-doping concentration (0, 1, 2 and 3 at.%) on microstructural, optical and electrical characteristics of layers have been investigated. The studies of X-ray diffraction and optical transmission spectra show these films have a hexagonal wurtzite structure with (002) preferred growth direction, also a high transmission of 85-95% in visible range. Data analysis show that the band gap energies in these films are varying in the range of 3.27-3.33 eV, consistent with the Burstein-Moss shift effect, with Urbach tail widths between 114-160 meV. The 2 wt% Ga sample showed the maximum figure of merit (3×10-2Ω-1), with an electron concentration and sheet resistance of ~1.42×1019 cm-3 and 13 kΩ/square, respectively.  

Effect of La Doping on ZnO Thin Films by Spray Pyrolysis

2019 ◽  
Vol 397 ◽  
pp. 206-212 ◽  
Author(s):  
Allag Nassiba ◽  
Ben Haoua Boubaker ◽  
Saied Chahnez ◽  
Barani Djamel ◽  
Segueni Leila ◽  
...  
Keyword(s):  
Thin Films ◽  
Spray Pyrolysis ◽  
Spray Pyrolysis Technique ◽  
Visible Region ◽  
Hexagonal Wurtzite Structure ◽  
Optical Transmittance ◽  
Zno Thin Films ◽  
Uv Detectors ◽  
Light Emitting ◽  
Doped Zno

In this study, Zinc oxide (ZnO) undoped and Lanthanum doped (ZnO: La) thin films were deposited on 400°C heated glass using spray pyrolysis technique with moving nozzle. The components (Zn (CH3COO)2, 2H2O) and (LaCl3, 7H2O) were used as sources to produce ZnO thin film and doped Lanthanum, respectively. Effects of dopant on the optical and structural properties of undoped and 0, 2 and 4 wt. % Lanthanum doped ZnO thin films were studied. Optical transmittance spectra of the films showed high transparency of about 98% in visible region. The optical gap for ZnO and 0, 2 and 4 wt. % La doped ZnO thin films were found to be in 3.25-3.28 [eV] range. The X-ray diffraction showed that the thin films have hexagonal wurtzite structure with a strong (002) as preferred orientation, whereas the crystalline size was ranged in 15.89-33.45 nm. The ZnO thin films are promising to be used a light emitting diodes, gas sensor and UV detectors applications.

Melioration of Optical and Electrical Performance of Ga-N Codoped ZnO Thin Films

2018 ◽  
Vol 73 (6) ◽  
pp. 547-553 ◽  
Author(s):  
Nripasree Narayanan ◽  
N. K. Deepak
Keyword(s):  
Thin Films ◽  
Energy Gap ◽  
Spray Pyrolysis Technique ◽  
Hole Concentration ◽  
Optical Transmittance ◽  
Electrical Performance ◽  
Zno Thin Films ◽  
Composition Analysis ◽  
Optical Energy Gap ◽  
X Ray

AbstractTransparent and conducting p-type zinc oxide (ZnO) thin films doped with gallium (Ga) and nitrogen (N) simultaneously were deposited on glass substrates by spray pyrolysis technique. Phase composition analysis by X-ray diffraction confirmed the polycrystallinity of the films with pure ZnO phase. Energy dispersive X-ray analysis showed excellent incorporation of N in the ZnO matrix by means of codoping. The optical transmittance of N monodoped film was poor but got improved with Ga-N codoping and also resulted in the enhancement of optical energy gap. Hole concentration increased with codoping and consequently, lower resistivity and high stability were obtained.

Polyaniline/SnO2 Nanocomposite Sensor for NO2 Gas Sensing at Low Operating Temperature

2015 ◽  
Vol 14 (04) ◽  
pp. 1550011 ◽  
Author(s):  
A. Sharma ◽  
M. Tomar ◽  
V. Gupta ◽  
A. Badola ◽  
N. Goswami
Keyword(s):  
Thin Films ◽  
Gas Sensing ◽  
High Sensitivity ◽  
Morphological Properties ◽  
X Ray Diffraction ◽  
Chemical Route ◽  
Sensing Properties ◽  
Response Recovery ◽  
Transmission Electron ◽  
Gas Sensing Properties

In this paper gas sensing properties of 0.5–3% polyaniline (PAni) doped SnO 2 thin films sensors prepared by chemical route have been studied towards the trace level detection of NO 2 gas. The structural, optical and surface morphological properties of the PAni doped SnO 2 thin films were investigated by performing X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Raman spectroscopy measurements. A good correlation has been identified between the microstructural and gas sensing properties of these prepared sensors. Out of these films, 1% PAni doped SnO 2 sensor showed high sensitivity towards NO 2 gas along with a sensitivity of 3.01 × 102 at 40°C for 10 ppm of gas. On exposure to NO 2 gas, resistance of all sensors increased to a large extent, even greater than three orders of magnitude. These changes in resistance upon removal of NO 2 gas are found to be reversible in nature and the prepared composite film sensors showed good sensitivity with relatively faster response/recovery speeds.

A comparative study on the NO2 gas sensing properties of ZnO thin films, nanowires and nanorods

2011 ◽  
Vol 520 (3) ◽  
pp. 932-938 ◽  
Author(s):  
S. Öztürk ◽  
N. Kılınç ◽  
N. Taşaltin ◽  
Z.Z. Öztürk
Keyword(s):  
Thin Films ◽  
Comparative Study ◽  
Gas Sensing ◽  
Zno Thin Films ◽  
Sensing Properties ◽  
Gas Sensing Properties
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