Properties Of Nickel Oxide Films Research Articles

Influence of oxygen flux on properties of nickel oxide films prepared by magnetron sputtering for alternative hole-transporting layer in inverted perovskite solar cells

Influence of oxygen flux on properties of nickel oxide films prepared by magnetron sputtering for alternative hole-transporting layer in inverted perovskite solar cells

Effects of Sputtering Pressure on Electrochromic Properties of NiO films Prepared by DC Magnetron Sputtering

In this paper, nickel oxide films were deposited on ITO-coated glass substrates by DC magnetron sputtering at different pressures(1.2 Pa ∼ 3.0 Pa). The effects of sputtering pressure on microstructure and electrochromic properties of nickel oxide films were investigated. The film thickness was measured by a surface profilometer. The crystal structure and surface morphology of the films were observed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochromic properties of the films were studied by combining UV-visible spectrophotometer with electrochemical workstation. The results showed that the nickel oxide film obtained the best surface morphology (uniform grain size and the fewer surface cracks) and outstanding electrochromic performances, including large transmittance modulation (ΔT = 57.19%), high coloration efficiency (CE = 33.59 cm2·C−1) and fast switching speed (tc = 4.63 s, tb = 4.87 s) at a wavelength of 550 nm when the sputtering pressure was 2.4 Pa. And after 500 electrochemical cycles, the transmittance modulation could continue to increase to 61.49% and the coloration efficiency can still be maintained at about 28.21 cm2·C−1, which showed excellent cycling durability.

Sputtering power effects on the electrochromic properties of NiO films

The effect of sputtering power (P=60 W–180 W) on the electrochromic properties of nickel oxide films deposited on ITO-coated glass substrates by the radio frequency magnetron sputtering technique was investigated. Crystalline structure and morphology were assessed by X-ray diffraction and scanning electron microscopy, respectively. The effect of sputtering power on electrochromism of the samples was evaluated with chronoamperometry, cyclic voltammetry, and electrochemical impedance spectroscopy. We used LiClO4 in a propylene carbonate solution for Li insertion/extraction. The chemical composition of the samples before and after Li intercalation was analyzed by X-ray photoelectron spectroscopy (XPS). We observed the cubic phase of NiO with sputtering power mainly affecting crystallinity and grain size. These in turn affect the electrochromic properties. Coloration efficiency reduces from 24.4 cm2/A⋅s to (15.4, 13.7, 16.1) cm2/A⋅s, and the reversibility from 40% to 30% as sputtering power increases from 60 W to 180 W. The impedance spectra indicates that ion diffusion is larger for the film grown at 60 W and then goes down for the films deposited at higher sputtering powers. XPS analysis reveals that higher values of P promote the formation of nickel hydroxides on the film surface. As a consequence of changes in crystallinity and morphology, the presence of nickel hydroxides increases showing that not only the electrochromic properties of the samples are affected by the sputtering power, but also their chemical composition.

Influence of Co concentration on properties of NiO film by sparking under uniform magnetic field

Nickel oxide (NiO) films cover numerous electronic applications, including transparent conducting oxides and hole transport layer, because of its high transparency and wide band gap. A sparking discharge is a new and unique method for the deposition of NiO films due to non-complex operation and non-requirement of a vacuum atmosphere. Unfortunately, NiO films by the sparking method display a porous surface with inferior crystallinity. By assisting a uniform magnetic field in the sparking method, the porous and the crystallinity of NiO are improved. However, electrical properties of the NiO films deposited by this strategy are poor. In order to improve the electrical properties of NiO, a substitutional of Ni ions by Co ions is considered. In this study, we report an influence of Co concentration on properties of NiO films by sparking under a uniform magnetic field. Our results indicate that an increase in Co concentration to 0.1 M improves the crystallinity and increases a carrier concentration of NiO, resulting in a reduction of the resistivity. This consequence is in agreement with the increase in a number of higher-valence Ni3+ because of the Co2+ substituted Ni2+. Based on our research, Co-NiO film is promising materials for a transparent conductor.

Investigation of the electrical and optical properties of nickel oxide films produced by RF magnetron sputtering method

Nickel oxide (NiO) thin films were deposited by an RF magnetron sputtering process in different atmospheres: one with a mixture of nitrogen and argon, and another with oxygen and argon. The structural, optical and electrical properties of NiO films were investigated using the spectroscopy, atomic-force microscopy and resistivity measurements. The dependencies of the film properties on atmosphere composition were studied. Optimization of the NiO thin film properties was carried out for further fabrication of effective hole transport layers for perovskite solar cells.

Influence of growth temperature on structure, optical and electrical properties of nickel oxide films by magnetron sputtering

Influence of growth temperature on structure, optical and electrical properties of nickel oxide films by magnetron sputtering

Microstructures and optoelectronic properties of nickel oxide films deposited by reactive magnetron sputtering at various working pressures of pure oxygen environment

Abstract Thanks to the intrinsic p-type conductivity, NiO films show great potential for applications in various domains. In this work, NiO x films were deposited in three dimensional physical vapor deposition (3D-PVD) system from metallic nickel target in pure oxygen conditions. Optical emission spectroscopy (OES) was employed to analyze the plasma state during the deposition. The variation of the film's structural and optoelectronic properties as a function of the oxygen pressure was investigated. It is found that the oxygen content in NiO x films is more evident for the films deposited with lower oxygen pressure. More Ni 3+ ions and interstitial oxygen associated with more Ni 2+ vacancies and holes are believed to exist in these films. Therefore, their conductivity is higher than the films deposited at higher oxygen pressure. Additionally, with an increase of oxygen pressure, the film's crystallinity is enhanced, and the film's transmittance as well as the film's band gap improves.

Influence of nitrogen doping on properties of NiO films

Undoped and nitrogen (N) doped nickel oxide (NiO) thin films were deposited onto glass substrates using a simplified spray pyrolysis technique with two different doping levels of N (10 and 20 at-%). The effects of N doping level on the structural, electrical and optical properties were studied and reported. From the structural studies, it is found that the preferential orientation changed from (111) to (200) for higher concentrations. The optical studies revealed that the average optical transmittance and optical band gap decreased (from 3·5 to 3·4 eV) due to N doping. The electrical resistivity decreased by one order (from 3·84E+03 Ωcm to 5·38E+02 Ωcm) in the case of higher doping of N. The defects generated by N doping were analysed using the photoluminescence studies. The size of the grains decreased due to N doping as seen from SEM studies.

Effect of UV Laser Irradiation on the properties of NiO films and ZnO/NiO Heterostructures

ABSTRACTThe present work accentuates the effect of UV laser irradiation on the conductivity of nickel oxide (NiO) thin films, deposited at various temperatures by radio-frequency reactive sputtering of Ni in oxygen containing atmosphere. The effect of UV irradiation on zinc oxide – nickel oxide heterostructures, obtained by sputtering, was examined as well. It was found that the resistivity of NiO changes from 12 Ω-cm to 0.62 Ω-cm, and the majority carrier concentration from 3.95x1017 holes/cm3 to 4.22x1020 electrons/cm3. The current-voltage (I-V) characteristics of the ZnO/NiO heterostructure shows an improved p-n diode behavior with the forward bias current increasing for the laser-irradiated ZnO/NiO compared to the as-deposited stack. The observed improvement in diode-like behavior suggests that laser irradiation can be an important technique to controllably change the structural, electrical and optical properties of metal oxide thin films.

Structures, electrical and optical properties of nickel oxide films by radio frequency magnetron sputtering

The NiO films were sputtered by radio frequency (rf) magnetron sputtering at different oxygen partial pressures. The structures, electrical and optical properties of the NiO films were investigated. The resulting films were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and ultraviolet–visible spectrophotometer (UV). The electrical properties were measured by Hall system. The results show that the NiO films deposited at room temperature with the ratio of oxygen partial pressures varying from 0 to 80% develop only (200) preferred orientation and very high optical transmittances. The lowest resistivity of 2.368 Ω cm and highest carrier density of 2.235 × 1019 cm−3 could be obtained. Comparatively, the controllable electrical properties of the films can be achieved by the variation of crystal quality arises from the oxygen partial pressures.

Sol–gel synthesis of nickel oxide thin films and their characterization

Sol–gel method has been employed for the synthesis of nanocrystalline nickel oxide (NiO). The NiO powders were sintered at 400–700°C for 1h in an air. Thin films of sintered powders were prepared on glass substrate using spin coating technique and changes in the structural, morphological, electrical and optical properties were studied. The structural and microstructural properties of nickel oxide films were studied by means of X-ray diffraction and field emission scanning electron microscopy. Structural analysis shows that all the films are crystallized in the cubic phase and present a random orientation. Surface morphology of the nickel oxide film consists of nanocrystalline grains with uniform coverage of the substrate surface with randomly oriented morphology. The electrical conductivity showed the semiconducting nature with room temperature electrical conductivity increased from 10−4 to 10−2 (Ω cm) −1 after sintering. The electron carrier concentration (n) and mobility (μ) of NiO films annealed at 400–700°C were estimated to be of the order of 1.30 to 3.75×1019cm−3 and 1.98 to 4.20×10−5cm2V−1s−1.The decrease in the band gap energy from 3.86 to 3.47eV was observed for NiO sintered between 400 and 700°C. These mean that the optical quality of NiO films is improved by sintering.

Electrochromic properties of Ni(1−x)O and composite Ni(1−x)O-polyaniline thin films prepared by the peroxo soft chemistry route

Electrochromic nickel oxide (Ni(1−x)O) thin films and composite nickel oxide–polyaniline (Ni(1−x)O–PANI) thin films were prepared by a new peroxo soft chemistry route based on a nickel acetate ionic solution precursor. The ionic solution was synthesized from nickel acetate, urea and hydrogen peroxide. The deep green colloidal solution for the preparation of nickel oxide films was prepared by digestion of ionic solution with ethanol. The polyaniline, PANI, was in-situ polymerized from aniline molecular precursor in the second step and then added to the colloidal nickel oxide sol to obtain a deep green–brown colloidal solution appropriate for deposition of composite Ni(1−x)O–PANI films. Thin xerogel films were deposited by a dip-coating technique on FTO glass substrates and heat treated at 300°C. Nano-crystalline non-stoichiometric Ni(1−x)O and composite Ni(1−x)O–PANI films were formed. The as-deposited Ni(1−x)O films exhibited a gray–black color, whereas the composite Ni(1−x)O–PANI films were almost transparent. The electrical, optical and electrochromic properties of all films were examined. The results showed that composite Ni(1−x)O–PANI films exhibit superior properties over plain Ni(1−x)O films. This confirmed the role of PANI, which was selected to improve the electrical and optical properties of nickel oxide films. The electrochromic properties of gray–black Ni(1−x)O and almost transparent composite Ni(1−x)O–PANI films were tested in a 1M LiClO4/propylene carbonate electrolyte. Spectroelectrochemical measurements showed charge capacities above 15mC/cm2 and coloring/bleaching changes from gray–black to transparent of more than 70%. Such changes are sufficient to enable the preparation of efficient electrochromic cells consisting of an anodic nickel oxide based counter electrode and cathodic WO3 electrochromic layer.

New process for synthesis of nickel oxide thin films and their characterization

Sol–gel spin coating method has been successfully employed for the deposition of nanocrystalline nickel oxide (NiO) thin films. The films were annealed at 400–700 °C for 1 h in an air and changes in the structural, morphological, electrical and optical properties were studied. The structural properties of nickel oxide films were studied by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD analysis shows that all the films are crystallized in the cubic phase and present a random orientation. Surface morphology of the nickel oxide film consists of nanocrystalline grains with uniform coverage of the substrate surface with randomly oriented morphology. The electrical conductivity showed the semiconducting nature with room temperature electrical conductivity increased from 10 −4 to 10 −2 (Ω cm) −1 after annealing. The decrease in the band gap energy from 3.86 to 3.47 eV was observed after annealing NiO films from 400 to 700 °C. These mean that the optical quality of NiO films is improved by annealing.

Optical, structural and electrochromic properties of nickel oxide films produced by sol–gel technique

Nickel oxide films have been deposited from nickel acetate precursor using a sol–gel dip coating method, onto glass and conducting fluorine doped tin oxide (FTO) glass substrate. The direct energy gap ( E gd) values for the 2–10 layered films are in the range of 3.62 eV–3.72 eV. X-ray diffraction (XRD) analysis reveals that films consisting of 2–6 layers are amorphous, while films consisting of 8–10 layers are poly-crystalline with cubic grains of around 12 nm–20 nm and preferential growth along the (1 1 1) and (2 0 0) planes. Fourier Transform Infrared (FTIR) spectrum confirms the formation of Ni–O. Electrochromic properties of the nickel oxide coatings were studied using cyclic voltammetric (CV) technique. The 8 layered NiO films exhibit the anodic/cathodic diffusion coefficient of 16.7/5.73 × 10 −13 cm 2/s and the change in optical transmission is Δ T 630nm = 53% with a photopic contrast ratio of 2.87.

Effect of Annealing on Structural, Morphological, Electrical and Optical Studies of Nickel Oxide Thin Films

Sol gel spin coating method has been successfully employed for the deposition of nanocrystalline nickel oxide (NiO) thin films. The films were annealed at 400°C - 700°C for 1 h in an air and changes in the structural, morphological, electrical and optical properties were studied. The structural properties of nickel oxide films were studied by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD analysis shows that all the films are crystallized in the cubic phase and present a random orientation. Surface morphology of the nickel oxide film consists of nanocrystalline grains with uniform coverage of the substrate surface with randomly oriented morphology. The electrical conductivity showed the semiconducting nature with room temperature electrical conductivity increased from 10-4 to 10-2(Ωcm)-1 after annealing. The decrease in the band gap energy from 3.86 to 3.47 eV was observed after annealing NiO films from 400oC - 700oC. These mean that the optical quality of NiO films is improved by annealing.

Structural, optoelectronic and electrochemical properties of nickel oxide films

Thin nickel oxide (NiO) films were deposited by the electron beam evaporation technique. The films were post annealed in air at 450–500 °C for 5 h and the effect of annealing on the structural, microstructural, electrical and optical properties were studied. X-ray diffraction studies indicated the polycrystalline nature of the films. The microstructural parameters were evaluated. The band gap of the films was found to be about 3.60 eV. Electrical resistivity of the films was 4.5 × 10−4 Ω cm. FTIR studies indicated a broad spectrum centered at 461.6 cm−1. Cyclic voltammetry studies in 1 M KOH solution revealed good electronic electrochromic behaviour.

Chemical deposition of nanocrystalline nickel oxide from urea containing bath and its use in liquefied petroleum gas sensor

Abstract Nanocrystalline nickel oxide (NiO) was deposited onto glass substrates using a chemical deposition method from a bath containing nickel (Ni 2+ ) ions and urea at 363 K. The deposition process was based on the reaction between Ni 2+ and hydroxide ions released from the protolysis of ammonia formed in the decomposition of urea heated at 363 K, which caused to form nickel hydroxide. The structural properties of nickel oxide films were studied by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD analyses showed that nanocrystalline nature remained after heating at 523 K for 2 h. Surface morphology of the nickel oxide film showed worm-like mesoporous structure with pore size in a nanometer range. The chemically deposited nickel oxide films were effectively used as a liquefied petroleum gas (LPG) sensor and the maximum response of 36.5% was recorded on exposure to 0.3 vol% of LPG at 698 K.

Electrochromic Properties of Nickel Oxide Film by Electroless

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Properties of Nickel Oxide Films by DC Reactive Sputtering

The electrical and micro-structural properties of polycrystalline nickel oxides grown by reactive direct current (DC) sputtering were investigated by current-voltage (I-V) measurements, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The oxygen content in the gas mixture was found to be an important parameter affecting the electrical properties of NiO films. At partial pressures above 10%, increasing the oxygen content during sputtering decreased the resistivity. The mechanism of electrical conductivity for the NiO films is discussed from the viewpoint of Nickel or Oxygen vacancies, which generate holes and electrons respectively, vacancy concentration was confirmed by Rutherford backscattering spectrometry (RBS).

Deposition and properties of nickel oxide films produced by DC reactive magnetron sputtering

Nickel oxide (NiO) thin films were prepared on Si substrates by DC reactive magnetron sputtering from a nickel metal target in Ar+O 2 with the relative O 2 content varied from 15 to 50%. The effects of the O 2 gas content on the deposition rate, structure, composition and electrical properties were investigated. NiO stoichiometric films were obtained with a polycrystalline structure and a specific resistivity of near 300 Ωcm at 25% O 2 content in the discharge gas. Film composition and structure, and this resistivity, were dependent on the discharge parameters. Thus the deposited films had amorphous and polycrystalline structures with Ni\\O ratio ranges between 0.71 and 1.02 as a function of the discharge O 2 content.