Ni-doped Films Research Articles

Investigation of structural, morphological and optoelectronic properties of (Ni, Co)-doped and (Ni/Co) co-doped SnO2 (110) sprayed thin films

The manuscript details the application of spray pyrolysis for the deposition of an economically viable transparent conductive oxide film comprised of (Ni/Co) co-doped SnO2 on a glass substrate. The primary objective of this research was to systematically examine the impact of Ni/Co co-doping on diverse properties of the SnO2 thin film. These properties encompassed the film's structural composition, surface morphology, optical response, and electrical behaviors. A comparison was made with pure SnO2 film, as well as SnO2 films doped with 3 %Ni and 1 %Co. The results indicate that all the samples exhibited a tetragonal structureThe introduction of Co and Ni atoms had no impact on the favored alignment of the (110) plane or the crystal structure of the SnO2 film. The crystallite size of the pure SnO2 film, as well as the (Co, Ni)-doped and (Ni/Co) co-doped SnO2 films, varied within the range of 11 to 20 nm. Scanning electron microscopy (SEM) images were employed to assess how doping and co-doping influenced the surface characteristics of the films. The presence of pores and/or roughness on the surface resulted in a hydrophilic character and a decrease in the contact angle for the doped films (Ni, Co). However, the co-doped film exhibited a hydrophobic characteristic due to the surface enhancement provided by SnO2:3 %Ni:1 %Co. The research also focused on the optical characteristics of the films, showing a positive impact with the proper incorporation of Ni and Co atoms into the SnO2 lattice. It was notably observed that the addition of Ni and Co atoms improves the optical properties of the undoped transparent SnO2 film in the visible spectrum, with a high transmittance of 87 % achieved for the Ni-doped film. Furthermore, the hydrophobic nature achieved by adding a concentration of 3 %Ni to the SnO2:1 %Co film enhances its optical transmission in the range of 300 nm to 750 nm. The SnO2 film shows an improvement in the electrical resistivity upon doping and co-doping with low resistivity value of 2.22 × 10−2 Ω.cm for the film (3 %Ni/1 %Co)-SnO2. Drawing from these insightful results, the study proposes the potential utilization of (Ni/Co) co-doped SnO2 films as transparent electrodes in optoelectronic applications, especially in the manufacturing of thin film solar cells.

Structural and optoelectronic properties of nickel doped CdO thin films deposited by spray pyrolytic technique

In this work, Cadmium oxide (CdO) and Nickle (Ni) doped cadmium oxide (CdO: Ni) thin films have been fabricated onto glass substrate by spray pyrolysis technique. The undoped and Ni-doped CdO thin films have been deposited at 400 °C heated glass substrate. The films' structure, morphology and optical properties were investigated & analyzed as a function of Ni doping level. As confirmed by different characterization, the preparade films have polycrystalline with cubic structure. Based on the results, the pure CdO films showed sharper and more intense diffraction patterns than Ni-doping films. Compared to the pure CdO films, the average grain size of the doped films decreases with increasing of doping level. Furthermore, the optical properties of Ni-doped CdO thin films showed lower absorption coefficient than pure films. However, the higher transparency of Ni-doped CdO films in the visible region consider a good window for the most optoelectronic devices applications. The energy band gap was tuned via Ni doping impurities and it increases as doping level increases.

Ni-doped SnO2 thin films for NO2 gas sensing application

Tin (IV) oxide (SnO2) and Nickel doped tin oxide thin films (NSO) were deposited by spray pyrolysis technique from an aqueous solution for gas sensing application. X-Ray Diffraction (XRD) analysis confirmed the tetragonal structure of pure SnO2 and Ni-doped films. The lattice parameters calculated for (NSO) decreased with increasing the Ni ratio. The average crystallites sizes deduced from Scherrer formula are between 5 and 8 nm.The FE-SEM reveals that films surface is response relatively homogeneous with good coverage of the substrate surface without any cracks. Increasing the Ni content causes the appearance of cauliflower aggregation structures of around 100 nm diameter and be denser at a high percentage of Ni. The Raman spectroscopy indicates the formation of SnO2 nanostructures and increases defects and vaccines by increasing the Ni contents. The NO2 gas sensors based on the NSO nanostructure sensor performance were enhanced toward NO2 at 100 °C with the best Ni ratio of 20 mol % compared to other tested ratios from 0 to 15%. The proposed device based on the NSO thin films is a low-cost sensor with good specifications.

Nickel doping induced amorphization of brookite TiO2: Photoluminescence enhancement

In this work, we have elaborated nickel doped TiO2 thin films by low temperature spray pyrolysis technique from ethanol based precursor. For the sample free of nickel, The FTIR spectrum reveals a large amount of organic species bonded to TiO2, resulting in a carbon-doped brookite. Ni doping causes extinction of the organic related peak that fade away for highly (> 10 %) Ni doped films. XRD spectra reveal the presence of brookite phase for low Ni amounts. While increasing Ni rate, the crystalline phase undergoes a transition to amorphous state and brookite XRD peaks vanishes. Optical and electronic (SEM) micrographs show a smooth surface with small brookite nanoparticles, for low Ni rate. Increasing Ni rate results in a fractured morphology composed of micrometric smooth ships. Optical absorption obtained by transmittance-reflectance spectra is enhanced in the transparency region of TiO2, by Ni doping due to the increase of defect density and the brookite to amorphous phase transformation. Visible and UV emission spectra are obtained from PL measurements at room temperature. A spectacular PL magnification is obtained for high Ni doping levels due to increase of oxygen vacancies in the amorphous film. However, thermal annealing at 500 °C causes recrystallization to anatase phase, leading to a dramatic PL quenching.

Hydrophilic nickel doped porous SnO2 thin films prepared by spray pyrolysis

This work deals with the preparation and characterization of pure and Nickel-doped porous Tin oxide (SnO2) thin films, using Spray pyrolysis technique for an eventual application in optoelectronics. The structural, morphological, optical, and electrical properties of these prepared samples were investigated using various techniques. X-ray diffraction analysis confirmed the tetragonal structure of pure SnO2 and Ni-doped films. The preferred orientation of the crystallites changed from (110) to (200) with the film doped at 15.3 at.% Ni, with crystallite size of about 10 and 18 nm for 15.3 at.% Ni-doped and 5.6 at.% Ni-doped SnO2, respectively. Scanning Electron Microscopy shows that the 15.3 at.% Ni-doped SnO2 film surface is relatively homogeneous, while the 5.6 at.% Ni-doped film is highly porous. The measured contact angles are less than 90° for all the prepared samples confirming the hydrophilic character of all the films. Transmittance as high as 85% in the visible region was observed for 5.6 at.% Ni-doped films, while lower transmittance is observed for 15.3 at.% Ni-doped films. A decrease of the optical band gap and the resistivity with increasing Ni dopant concentration were also observed.

Atom doping in α-Fe2O3 thin films to prevent hydrogen permeation

Prevention of hydrogen (H) penetration into passive films and steels plays a vital role in lowering hydrogen damage. This work reports effects of atom (Al, Cr, or Ni) doping on hydrogen adsorption on the α-Fe2O3 (001) thin films and permeation into the films based on density functional theory. We found that the H2 molecule prefers to dissociate on the surface of pure α-Fe2O3 thin film with adsorption energy of −1.18 eV. Doping Al or Cr atoms in the subsurface of α-Fe2O3 (001) films can reduce the adsorption energy by 0.03 eV (Al) or 0.09 eV (Cr) for H surface adsorption. In contrast, Ni doping substantially enhances the H adsorption energy by 1.08 eV. As H permeates into the subsurface of the film, H occupies the octahedral interstitial site and forms chemical bond with an O atom. Comparing with H subsurface absorption in the pure film, the absorption energy decreases by 0.01–0.22 eV for the Al- and Cr-doped films, whereas increases by 0.82–0.96 eV for the Ni-doped film. These results suggest that doping Al or Cr prevents H adsorption on the surface or permeation into the passive film, which effectively reduces the possibility of hydrogen embrittlement of the underlying steel.

Selective detection of ammonia using spray pyrolysis deposited pure and nickel doped ZnO thin films

Abstract This research paper reports the deposition of nanostructured pure and Ni-doped ZnO thin films deposited at the substrate temperature of 523 K using simple and economical spray pyrolysis technique and subsequently post annealed at 673 K in air atmosphere for 3 h. Ni-doping greatly affected the crystallographic orientation, surface morphology, roughness and room temperature sensing response. Noticeable change in the crystallite size, transmittance and electrical properties was observed. The room temperature sensing characteristics like selectivity, response recovery studies, range of detection, stability and reproducibility of the undoped and Ni-doped ZnO thin films were investigated. Especially, the sensing elements exhibited an excellent selectivity towards ammonia. A lower detection limit of 5 and 25 ppm was observed for undoped and Ni-doped ZnO thin films respectively. The upper detection range was widened to 1000 ppm for the Ni-doped film.

RETRACTED: Photocurrent enhancement by Ni2+ and Zn2+ ion doped in SnO2 nanoparticles in highly porous dye-sensitized solar cells

Searching on alternative photoanode materials for dye-sensitized solar cells (DSSCs) evidenced that rare works have been reported on studying Ni2+ and Zn2+ doped SnO2 nanoparticles. Mostly efficient DSSCs with perfect long-term stability were fabricated based on tin (IV) oxide (SnO2) nanocrystals doped with different metals ions. The co-precipitation technique was applied to prepare M-doped SnO2 nanoparticles. Moreover, the obtained powders were investigated using XRD, HRTEM, BET specific surface area (SBET) and UV–vis spectroscopy. In addition, an economic way to prepare semiconducting pastes for photoanodes was devised. The photovoltaic performance of dye-sensitized solar cells based on undoped and Ni2+ and Zn2+ doped SnO2 photoanodes was investigated. Zn and Ni doped SnO2, respectively, have a high power conversion efficiency of up to 4.2% and 3.6%, higher than that of undoped SnO2 which is 3.2% and the reason for this difference is that the Zn and Ni-doped films exhibit an elevated electron Fermi level, which may enhance band bending to lower the density of empty trap states. On account of these doping metals, the consequent DSSCs can alleviate the decay of light to electric energy conversion efficiency due to light intensity reduction. The enhanced transport of photogenerated electrons as a result of the trap density minimization is responsible for the high photovoltaic performance.

Low Electrical Resistivity of Ni-Doped La-Cobaltite Thin Films Using a Novel Chemical Solution Route for Thermoelectric Applications

5 mol % Ni substituted La-cobaltite thin films were successfully prepared by using metal salt precursors-based chemical solution route for thermoelectric applications. We systematically investigated the optimized process conditions for the low-cost effective thermoelectric thin film preparation. The La(Co0.95Ni0.05)O3 thin film showed a fully crystalline perovskite structure after 650 °C annealing process without any second phase. The film showed relatively dense and uniform microstructure with very fine and homogeneous grains. For the oxide-based thermoelectric applications, one of the important key parameters is to reduce the electrical resistivity of the films. It was clarified that Ni substitution played a great role for reducing the electrical resistivity of the films. The average resistivity value of the Ni-doped films was around 0.18 Ω cm at room temperature, which was approximately over two times lower value than that of the undoped La-cobaltite thin films.

Effect of nickel doping on the photocatalytic activity of ZnO thin films under UV and visible light

Nanostructured ZnO thin films with different concentrations of Ni2+ doping (0, 1, 5, 10 and 15wt.%) are prepared by the sol–gel method for the first time. The thin films are prepared from zinc acetate, 2-methoxyethanol and monoethanolamine on glass substrates by using dip coating method. The films comprise of ZnO nanocrystallites with hexagonal crystal structure, as revealed by X-ray diffraction. The film surface is with characteristic ganglia-like structure as observed by Scanning Electron Microscopy. Furthermore, the Ni-doped films are tested with respect to the photocatalysis in aqueous solutions of malachite green upon UV-light illumination, visible light and in darkness. The initial concentration of malachite green and the amount of catalyst are varied during the experiments. It is found that increasing of the amount of Ni2+ ions with respect to ZnO generally lowers the photocatalytic activity in comparison with the pure ZnO films. Nevertheless, all films exhibit a substantial activity under both, UV and visible light and in darkness as well, which is promising for the development of new ZnO photocatalysts by the sol–gel method.

Influence of Ni-dopant on structural and optical properties of Ba0.6Sr0.4TiO3 thin film by sol-gel technique

The pure and Ni-doped Ba0.6Sr0.4TiO3 thin films were prepared on Si and LaNiO3/Si substrates via sol-gel technique, respectively. The microstructure and surface morphology of the films were characterized using x-ray diffraction and atomic force microscope. The films on LaNiO3/Si substrate were well-crystallized of the perovskite structure, and the diffraction peaks corresponded to BST standard pattern quite well. The Raman spectra showed the Ni dopant could improve the crystal quality of the BST films on Si substrate. The optical properties of the pure and Ni-doped films were studied by spectroscopic ellipsometry at room temperature.

Pulsed laser deposition and thermal characterization of Ni-doped La5Ca9Cu24O41 thin films

Highly b-axis oriented polycrystalline Ni-doped La 5Ca 9Cu 24O 41 thin films have been grown on (0 0 1) SrTiO 3 substrates using the pulsed laser deposition technique. EDX measurements have revealed nearly stoichiometric target-to-film transfer of Ni concentration up to 6.6 at.%. The 3ω method has been employed to carry out thermal conductivity measurements in the range 90–300 K. The results indicate that the out-of-plane thermal conductivity ( κ b ) decreases with increasing Ni doping level. The temperature dependence of κ b observed in pristine and Ni-doped films is similar to that observed in polycrystalline pellets indicating that the grain boundaries play a significant role in the heat transport.

Electrical and Mechanical Characteristics of Co-Doped and Ni-Doped Carbon Thin Films

To create conductive and wear-durable carbon thin films using metal doping, we deposited Co-doped and Ni-doped carbon thin films onto silicon substrates by RF sputtering. Then we evaluated the dopant concentrations, resistivity, scratch hardness, carbon sp2 and sp3 bonding fractions, and the microscopic structure of the films. The resistivity of the Co-doped film remarkably decreased compared to that of non-doped carbon film when the dopant concentration was 1 at.% and it slightly decreased when the dopant concentration increased. The Ni-doped film resistivity decreased when the dopant concentration increased. The scratch hardness of the Co-doped and Ni-doped films was approximately equal to that of the non-doped film when the metal concentrations of the films were less than 6 and 5 at.%, respectively. The scratch hardness of the Co-doped film was degraded slightly as the dopant concentration became greater than 7 at.%. However, the scratch hardness of the Ni-doped film was significantly degraded when the dopant concentration was greater than 7 at.%. The Co-doped film with dopant concentration less than 12 at.% was most suitable from a practical perspective because of its low resistivity and high scratch hardness.

Synthesis and characterization of Ni-doped ZnO: A transparent magnetic semiconductor

We report synthesis of a transparent magnetic semiconductor by incorporating Ni in zinc oxide (ZnO) matrix. ZnO and nickel-doped zinc oxide (ZnO:Ni) thin films (∼60 nm) are prepared by fast atom beam (FAB) sputtering. Both undoped and doped films show the presence of ZnO phase only. The Ni concentration (in at%) as determined by energy dispersive X-ray (EDX) technique is ∼12±2%. Magnetisation measurement using a SQUID magnetometer shows that the Ni-doped films are ferromagnetic, having coercivity ( H c) values 192, 310 and 100 Oe and saturation magnetization ( M s) values of 6.22, 5.32 and 4.73 emu/g at 5, 15 and 300 K, respectively. The Ni-doped film is transparent (>80%) across visible wavelength range. Resistivity of the ZnO:Ni film is ∼2.5×10 −3 Ω cm, which is almost two orders of magnitude lower than the resistivity (∼4.5×10 −1 Ω cm) of its undoped counterpart. Impurity d-band splitting is considered to be the cause of increase in conductivity. Interaction between free charges generated by doping and localized d spins of Ni is discussed as the reason for ferromagnetism in the ZnO:Ni film.

Effects of nickel doping on structural and optical properties of spinel lithium manganate thin films

Spinel LiNi x Mn 2− x O 4 ( x ≤ 0.9 ) thin films were synthesized by a sol–gel method employing spin-coating. The Ni-doped films were found to maintain cubic structure at low x but to exhibit a phase transition to tetragonal structure for x ≥ 0.6 . Such cubic–tetragonal phase transition can be explained in terms of Ni 3+(d 7) ions with low-spin (t 2g 6,e g 1) configuration occupying the octahedral sites of the compound, thus being subject to the Jahn–Teller effect. By X-ray photoelectron spectroscopy both Ni 3+ and Ni 2+ ions were detected where Ni 2+ is more populated than Ni 3+. Optical properties of the LiNi x Mn 2− x O 4 films were investigated by spectroscopic ellipsometry in the visible–ultraviolet range. The measured dielectric function spectra mainly consist of broad absorption structures attributed to charge-transfer transitions, O 2−(2p)→Mn 4+(3d) for 1.9 (t 2g) and 2.8–3.0 eV (e g) structures and O 2−(2p)→Mn 3+(3d) for 2.3 (t 2g) and 3.4–3.6 eV (e g) structures. Also, sharp absorption structures were observed at about 1.6, 1.7, and 1.9 eV, interpreted as being due to d–d crystal-field transitions within the octahedral Mn 3+ ion. In terms of these transitions, the evolution of the optical absorption spectrum of LiMn 2O 4 by Ni doping could be explained and the related electronic structure parameters were obtained.

Surface segregation of transition metals in sol-gel silicafilms

Silica sol-gel films (SGFs) doped with various transition metalsderived by spin-coating on glass substrates and silicon wafers have beenstudied. Precursor solutions were prepared by mixing tetraethylorthosilicate,ethanol, water and nitrates of the transition metals (Cr, Mn, Fe, Co, Ni andCu) using HCl as a catalyst. Remarkable segregation of metals at the surfacewas observed for films doped with Cu and Co. For Mn- and Ni-doped films thiseffect was much less, and it vanished for the films doped with Cr or Fe. Theinfluence of boron and phosphorus upon the chemical state and the distributionof metal atoms was also analysed. The structure, optical properties andcomposition of the SGFs were studied and some pathways to control the dopantsegregation effect were realized.

Optical and microstructural properties of TiO 2(Ni 2+) thin films

Coloured TiO 2(Ni 2+) thin coatings doped with transitional metals (Ni) were deposited on different substrates (silicon wafers, glass, aluminum) by the sol-gel dip coating process. Complementary techniques (XPS, SE, TEM, XRD, Absorption Spectroscopy) were used to characterize the surface stoichiometry and optical properties, as well as the structure and texture of the thermally treated gels. The presence of fully oxidized film in the outer layers, crystallization in heat treatment to anatase and rutile, formation of porous and coloured films due to the influence of the dopant and the reaction with the substrate, as well as a decrease by three orders of magnitude of the resistivity of Ni-doped films, are reported.

Infrared reflectance of YBa 2(Cu 1−xNi x) 3O 7−δ films

In this paper, we report the infrared reflectance R( v,T) of a YBa 2Cu 3O 7−δ film in which 6% of the Cu atoms have been substituted by Ni. These spectra are taken with better resolution than in our earlier report of films with up to 4% Ni. The reflectance spectra for the 6% Ni-doped film are very similar to those fora 4% Ni-doped film, thus confirming our earlier conclusions about the very non-BCS gapless nature of the optical conductivity. The new spectra make evident a plateau at R = 96% for v < 150cm −1 and a sharp decrease in R for v > 150cm −1. These features imply an interesting non-Drude structure in the superconducting density of states in the infrared.