Cobalt Oxide Films Research Articles

Synthesis and Characterization Studies of Pure and Co Doped ZnO Nano Thin Films

General Background: Thin-film technology is pivotal in advancing modern optoelectronic devices due to its ability to tailor material properties at the nanoscale. Specific Background: Zinc oxide (ZnO) and cobalt oxide (CoO) are prominent materials in this field, with doping techniques such as cobalt incorporation offering potential enhancements in film properties. Knowledge Gap: The impact of cobalt doping on the structural and optical properties of ZnO thin films remains inadequately explored, particularly concerning varying doping concentrations. Aims: Aims to elucidate the effects of cobalt doping on ZnO thin films' structural and optical characteristics, with concentrations of Zn0.6Co0.4O and Zn0.8Co0.2O compared to pure ZnO and CoO films. Results: Thin films were prepared via spin coating on glass substrates at 3000 rpm for 30 seconds. X-ray diffraction analysis revealed that pure ZnO films possess a hexagonal polycrystalline structure, whereas CoO films exhibit a cubic structure. Doping with cobalt resulted in a decrease in peak intensity at the (111) orientation and an increase in grain size. Optical measurements indicated enhanced transmittance and modified absorbance spectra with increased cobalt content, showing maximum absorbance at short wavelengths and diminished values in the visible region. Reflectivity increased with photon energy before decreasing at higher energies. Novelty: Cobalt doping significantly alters both structural and optical properties of ZnO films, with distinct changes in lattice constants, grain size, and optical behavior, suggesting a potential route for optimizing ZnO-based materials. Implications: Cobalt-doped ZnO films hold promise for improved performance in optoelectronic applications, such as solar cells and sensors, necessitating further research into diverse doping strategies to fully harness their technological potential. Highlights: Cobalt doping alters ZnO thin films' structural and optical properties. Spin coating method used at 3000 rpm for 30 seconds. Enhanced optical properties suitable for optoelectronic applications. Keywords: Thin films, Zinc oxide, Cobalt doping, Optical properties, X-ray diffraction

Preparation, Characterization, and Bioactivities of Cobalt, Strontium and Fluorine Co-Doped Oxide Films on Titanium Surface for Clinical Application

Titanium and titanium alloys are receiving widespread attention due to their excellent comprehensive mechanical properties, corrosion resistances, and biocompatibilities. However, titanium metal itself is biologically inert in physiological environments, and after implantation, it is surrounded by a layer of encapsulating fibrous membrane, making it difficult to form solid bonds with the tissue. Plasma electrolytic oxidation is a new technology used to prepare bioactive porous ceramic membranes on the surfaces of titanium and titanium alloys. It has application prospects for biomimetic surface modifications of titanium alloys. In this study, a cobalt, strontium and fluorine codoped oxide film (TAM-CSF) was prepared on a titanium surface via plasma electrolytic oxidation. The surface characteristics of the film were evaluated with field emission scanning electron microscopy, energy spectrum analyses, atomic force microscopy, profilometry and X-ray photoelectron spectroscopy. Additionally, the corrosion performance of the material was evaluated with an electrochemical workstation. The biocompatibility and bioactivity of the film were tested with in vitro cell experiments. The results showed that the TAM-CSF on the titanium surface had a porous morphology, and the CSF was uniformly doped on the film surface. TAM-CSF improved the surface roughness of the titanium. This film exhibited good biocompatibility and promoted the extension and proliferation of MC3T3-E1 cells. It was possible to prepare TAM-CSF on titanium surfaces via plasma electrolytic oxidation. The film exhibited a good morphology and good biological activity and has clinical application prospects.

Growth of ultrathin cobalt oxide films on Pd(100): Refined structural model

We present an atomistic-level study on the growth of cobalt oxide ultra-thin films prepared on Pd(100) substrate performed by a combination of scanning tunneling microscopy (STM) and Low Energy Electron Diffraction (LEED). In this contribution, we report a new surface structure c(12×2)-CoO(111), which co-exist with the previously reported extended c(4 × 2)-CoO(100) domains at low Co deposition coverages. We demonstrate that the lattice parameters derived for the newly observed hexagonal c(12×2)-CoO(111) phase fit the three- or sixfold lattice parameter of the c(4 × 2)-CoO(100) layer. The c(12×2)-CoO(111) layer was shown to grow directly on top of the c(4 × 2)-CoO(100) structure, offering a transition mechanism from rectangularly to hexagonally terminated CoO surface. At growing Co coverages, HEX-CoO(111) domains exhibiting a Moiré pattern followed by the formation of well-defined Co3O4(111) islands, were prepared and structurally characterized. Both latter phases have been previously reported in the literature. Finally, we provide a refined model for the epitaxial growth of cobalt oxide thin films on Pd(100), including the formation of new c(12×2)-CoO(111) phase.

In-situ hydrothermal synthesis of a novel morphology daisy shape nickel cobalt oxide films for high performance supercapattery

NiCo2O4 is widely used in traditional battery and supercapattery due to its extremely high capacitance value. Herein, the in-situ hydrothermal method has been optimized in order to utilize its own charge storage capacity. NiCo2O4 nanosheet thin films with four different morphologies (wrap, neuron, daisy, and tablet shape) are synthesized on Ni foam surface without mechanical stress damage. In the absence of interference from conductive agents and binders, these NiCo2O4 nanosheet thin films with different morphologies provide various conducive channels for charge transfer and more sites for redox reactions achieve better energy storage properties. Particularly, the daisy shape NiCo2O4 nanosheets have the highest capacity (C g−1) of 972.5 (2 M KOH) at 1 A g−1 comparing to others. Furthermore, after subjecting it to 1800 cycles of cyclic stability testing at 40 A g−1, its capacity (C g−1) remarkably increased to 1433.5. In addition, using the daisy shape NiCo2O4 nanosheets thin film and activated carbon, a supercapattery is assembled. The results exhibit that it has an impressive performance of 39.8 W h kg−1 at 750 W kg−1 comparing to other works, which demonstrates that our in-situ hydrothermal synthesized daisy shape NiCo2O4 nanosheet has significant potential in the field of energy storage.

Epitaxial Growth of Cobalt Oxide Thin Films on Sapphire Substrates Using Atmospheric Pressure Mist Chemical Vapor Deposition

This study demonstrated the epitaxial growth of single-phase (111) CoO and (111) Co3O4 thin films on a-plane sapphire substrates using an atmospheric pressure mist chemical vapor deposition (mist-CVD) process. The phase structure of the grown cobalt oxide films was manipulated by controlling the growth temperature and process ambient, confirmed through X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy. Furthermore, the electrical properties of Co3O4 films were significantly improved after thermal annealing in oxygen ambient, exhibiting a stable p-type conductivity with an electrical resistivity of 8.35 Ohm cm and a carrier concentration of 4.19 × 1016 cm−3. While annealing CoO in oxygen atmosphere, the Co3O4 films were found to be most readily formed on the CoO surface due to the oxidation reaction. The orientation of the atomic arrangement of formed Co3O4 was epitaxially constrained by the underlying CoO epitaxial layer. The oxidation of CoO to Co3O4 was largely driven by outward diffusion of cobalt cations, resulting in the formation of pores in the interior of formed Co3O4 films.

Effect of Ni substitution on the antiferromagnetic domains of cobalt oxide

We present a spatially resolved X-ray magnetic linear dichroism study of high quality micron-sized mixed nickel-cobalt oxide (NCO) crystals. NixCo1−xO was prepared in-situ by high-temperature oxygen-assisted molecular beam epitaxy on a Ru(0001) single crystal substrate. To check the effect of incorporating Ni into the cobalt oxide films, three different compositions were prepared. The element-specific XMLD measurements reveal strong antiferromagnetic contrast at room temperature and magnetic domains up to one micron in size, reflecting the high structural quality of the NCO islands. By means of vectorial magnetometry, the antiferromagnetic spin axis orientation of the domains was determined with nanometer spatial resolution, and found to depend on the stoichiometry of the prepared crystals.

Effect of applied potential on the optical and electrical properties of Cu2CoO3

The effect of the applied potential on the crystallography, morphology, optical, and electrical properties of copper-cobalt oxide (Cu2CoO3) co-electrodeposited on ITO (Indium Tin Oxide) substrate has been studied. The electrochemical behavior of Cu2CoO3 using cyclic voltammetry showed that the co-electrodeposition of Cu2CoO3 occurred at a negative potential of - 0.70 V versus SCE, following a quasi-reversible reaction controlled by the diffusion process. Chronoamperometry (CA) revealed that the nucleation and growth mechanism of Cu2CoO3 follows the instantaneous three-dimensional process according to Scharifker and Hill model. X-ray diffraction (XRD) analysis indicated that the resulting layers at different applied potentials exhibited an orthorhombic structure with a preferred orientation of the crystallites (011) plan. The morphology of the surface changes with potential applied. Furthermore, the optical properties of the copper and cobalt oxide films were investigated using UV-visible spectroscopy; showing that the band gap energy for all the materials increases when the applied potential decreases. The Cu2CoO3 layers obtained are p-type semiconductors. The acceptor density (NA) increases with decreasing applied potential.

A combined spectroscopic investigation of cobalt oxide films prepared by DC reactive sputtering

The structure and vibrational characteristics of cobalt monoxide and tetraoxide films, prepared by direct-current DC reactive sputtering, were investigated by different characterization techniques. According to X-ray diffraction analyses, the development of the Co3O4 phase takes place under low discharge power and high substrate temperature (80 W-623 K) conditions, whereas the CoO phase predominates when adopting high discharge power and low substrate temperature (240 W-473 K). Results of infrared absorption and Raman scattering spectroscopies indicate the presence of Co3O4 in all films, that are compatible with the optical transmittance spectra in the UV-Vis-NIR range − showing electronic transitions due to Co2+/3+ cations (related to the Co3O4 spinel structure) in the films deposited at 80 W-623 K and, to a lesser extent, at 240 W-473 K conditions. The investigations include Raman scattering measurements in the 83–623 K range. The results evidence a mixture of phases in the 240 W-473 K film, whose main Raman scattering peaks evolve irreversibly towards Co3O4 upon increasing measurement temperatures. Altogether, the present report provides deeper information about the cobalt oxide phases that shall be useful to improve the control of properties and production of cobalt oxide films by DC reactive sputtering.

Physical properties of Ni: Co3O4 thin films and their electrochemical performance

In this research work, we have deposited cobalt oxide as pure and Ni-doped thin films using spray pyrolysis. The concentration of Ni has been changed from 0 to 6 wt% in all films while other deposition parameters are fixed. The characterization of deposited films has been c using X-ray diffraction (XRD), energy dispersive x-ray spectroscopy (EDX), x-ray photoelectron microscope (XPS), scanning electron microscope (SEM), and optical spectroscopy. The XRD results confirm the formation of Co3O4 as the low-temperature stable phase of cobalt oxide and the successful doping with nickel. The XRD also shows the preferred orientation of growth of film is along the (111) plane and the crystallite size was found to decrease with increasing Ni content. The SEM micrograph of the deposited film surfaces revealed that the samples are porous and in some parts of the sample, the particles are agglomerated due to doping. The Ni doping was confirmed by both EDX and XPS. The Ni concentration was found to increase according to dopant concentration. The XPS data of the 4 wt% film has been recorded which confirms the existence of Ni+2 in the deposited films. Both optical transmission and reflection spectra have been recorded using a spectrophotometer. The band gap values have been found to decrease upon Ni-doping. The electrochemical properties of the pure and nickel-doped cobalt oxide films were measured by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) in 0.3 M KOH electrolyte. The specific capacitance of 4 wt% Ni doped Co3o4 was found to be 804 Fg-1 at a 2 mVs−1 scan rate which is 90% higher than pure films. The important property of this material is that it shows excellent retention of 96% and remains almost constant for 10000 cycles. The impedance analysis reveals that 4 wt% Ni doped cobalt oxide film has the lowest RS value of 0.2 Ω cm−2 and lowest RCT value of 0.05 Ω cm−2 in comparison to other films which have excellent super-capacitive nature. These outstanding electrochemical properties of 4 wt % Ni-doped Co3O4 thin film have made it a potential candidate for anode material in supercapacitor devices.

Enhancing magneto-ionic effects in cobalt oxide films by electrolyte engineering.

Electric-field-driven ion motion to tailor magnetic properties of materials (magneto-ionics) offers much promise in the pursuit of voltage-controlled magnetism for highly energy-efficient spintronic devices. Electrolyte gating is a relevant means to create intense electric fields at the interface between magneto-ionic materials and electrolytes through the so-called electric double layer (EDL). Here, improved magneto-ionic performance is achieved in electrolyte-gated cobalt oxide thin films with the addition of inorganic salts (potassium iodide, potassium chloride, and calcium tetrafluoroborate) to anhydrous propylene carbonate (PC) electrolyte. Ab initio molecular dynamics simulations of the EDL structure show that K+ is preferentially located on the cobalt oxide surface and KI (when compared to KCl) favors the accumulation of positive charge close to the surface. It is demonstrated that room temperature magneto-ionics in cobalt oxide thin films is dramatically enhanced in KI-containing PC electrolyte at an optimum concentration, leading to 11-fold increase of generated magnetization and 35-fold increase of magneto-ionic rate compared to bare PC.

Strong spin-lattice entanglement in cobaltites

Strongly correlated electronic system contains strong coupling among multi-order parameters and is easy to efficiently tune by external field. Cobaltite (LaCoO<sub>3</sub>) is a typical multiferroic (ferroelastic and ferromagnetic) material, which has been extensively investigated over decades. Conventional research on cobaltites has focused on the ferroelastic phase transition and structure modulation under stress. Recently, researchers have discovered that cobaltite thin films undergo a paramagnetic-to-ferromagnetic phase transition under tensile strain, however, its origin has been controversial over decades. Some experimental evidence shows that stress leads the valence state of cobalt ions to decrease, and thus producing spin state transition. Other researchers believe that the stress-induced nano-domain structure will present a long-range ordered arrangement of high spin states, which is the main reason for producing the ferromagnetism of cobalt oxide films. In this paper, we review a series of recent researches of the strong correlation between spin and lattice degrees of freedom in cobalt oxide thin films and heterojunctions. The reversible spin state transition in cobalt oxide film is induced by structural factors such as thin-film thickness, lattice mismatch stress, crystal symmetry, surface morphology, interfacial oxygen ion coordination, and oxygen octahedral tilting while the valence state of cobalt ions is kept unchanged, and thus forming highly adjustable macroscopic magnetism. Furthermore, the atomic-level precision controllable film growth technology is utilized to construct single cell layer cobaltite superlattices, thereby achieving ultra-thin two-dimensional magnetic oxide materials through efficient structure regulation. These advances not only clarified the strong coupling between lattice and spin order parameters in the strongly correlated electronic system, but also provided excellent candidate for the realization of ultra-thin room temperature ferromagnets that are required by oxide spintronic devices.

Oriented growth of stacking α-cobalt hydroxide salt continuous films and their topotactic-like transformation to oriented mesoporous films of Co3O4 and CoO.

Mesoporous metal oxide films composed of nanocrystal assemblies with an aligned crystallographic orientation are key nanostructures for efficient interfacial reactions; however, the development of a simple and versatile method for their formation on substrates still constitutes a challenge. Here we report the template-free centimetre-scale formation of novel cobalt oxide films of Co3O4 and CoO with a [111]-oriented mesoporous structure starting from stacking cobalt hydroxide continuous films. The cobalt hydroxide precursor is formed electrochemically on conductive substrates from a Co(NO3)2 aqueous solution at room temperature. A thorough characterization by means of scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis-NIR spectroscopy, IR spectroscopy and Raman spectroscopy analyses reveals that the precursor film is an α-type layered cobalt hydroxide salt (α-Co-LHS) containing interlayer nitrate and hydrated water, i.e., α-Co(OH) x (NO3) y ·nH2O, with a [001]-oriented stacking film structure. Heat treatment of the [001]-α-Co-LHS films using different conditions, i.e., under air at 550 °C or under vacuum at 500 °C, results in the selective formation of Co3O4 or CoO mesoporous films, respectively. A plausible explanation for the observed centimetre-scale topotactic-like transformation from α-Co-LHS[001] to Co3O4[111] or CoO[111] is given according to the atomic framework similarity between the hydroxide precursor and the final oxides.

Resistive switching behaviors of cobalt oxide films with structural change by post-thermal annealing

We have studied the resistive switching behaviors of cobalt oxide films with structural changes by a post-thermal annealing process. During post-annealing at temperatures of 500–700 °C for the CoOx films deposited by ultra-high-vacuum RF magnetron sputtering, two structural phases of CoO and Co3O4 were modulated by selection of ambient N2 or O2 gases. As a device application of these films, the resistive random-access memory (ReRAM) structures of p+-Si/CoOx/Ti/Au were fabricated with CoO or Co3O4 films by post-annealing at 700 °C under N2 and O2 atmosphere, respectively. The resistive switching characteristics of the CoO device appeared much better than that of the Co3O4 device, also showing good uniformity from a cumulative probability distribution, long non-volatile retention characteristics of 104 s, good endurance of ∼100 cycles, and an excellent current ratio of 104. These results demonstrate the method to provide stable and good resistive switching properties of sputtered CoO films using the phase selection during post-thermal annealing.

A study of the NF3 plasma etching reaction with cobalt oxide films grown on an inorganic compounds

In this study, an NF3 plasma etching reaction with a cobalt oxide (Co3O4) films grown on the surface of inorganic compounds using granite was investigated. Experimental results showed that the etching rate can be up to 1.604 μm/min at 380 °C under 150 W of RF power. EDS and XPS analysis showed that main reaction product is CoF2, which is generated by fluorination in NF3 plasma. The etching rate of cobalt oxide films grown on inorganic compounds in this study was affected by surface roughness and etch selectivity. This study demonstrates that the plasma surface decontamination can effectively and efficiently remove contaminated nuclides such as cobalt attached to aggregate in concrete generated when decommissioning of nuclear power plants.

Preparation of Spinel Form Co3O4 and CoO2 Thin Film at Low Temperature by Electrochemical Method as a Thin Film Oxide Layer

In this work, thin films of cobalt oxides (CoO2, Co3O4) were prepared using the electrochemical method on the pencil graphite and indium tin oxide surfaces. The substrate effect in the production of both oxides has been studied in detail. While Co3O4 accumulates on the pencil graphite’s surface, CoO2 formation was observed on the indium tin oxide. The characterization of the cobalt oxides was carried out using the X-ray diffraction, Atomic force microscope, and Scanning electron microscope. In this context, the cobalt oxide crystal structure in the range of (−1.0 V)–(+1.9 V) was synthesized on different substrates and at extremely low temperatures (20 °C to 25 °C), using the cyclic voltammetry method, which is a simple one-stage way. Calculated band gap value for ITO/CoO2 as 2.5 eV shows a potential use of this electrode in solar cell applications.

FORMATION AND ELECTROCHEMICAL PROPERTIES OF NICKEL AND COBALT TRANSITION METALS OXIDE FILMS

Films of cobalt oxide and nickel oxide on monocrystalline silicon substrates were obtained by electrochemical deposition from aqueous electrolyte solutions. Their structure and composition were studied by Raman microscopy and scanning electron microscopy. The results of the study by Raman spectroscopy showed that the obtained films are polycrystalline structures of cobalt (II, III) oxide and nickel (II) oxide, the crystalline perfection of which increases with an increase in the electrolyte temperature. It was found by scanning electron microscopy that nickel oxide films have a smoother surface, while cobalt oxide has a more developed structure consisting of lamellar crystals. The specific electrochemical capacity of cobalt oxide and nickel oxide films obtained under optimal conditions, measured by voltammetry, was 14.67 and 1634.08 F/g, respectively. The high specific electrochemical capacity of a nickel oxide film can be used to create efficient electrochemical devices and energy storage devices.

A comprehensive study on structure, opto-nonlinear and photoluminescence properties of Co3O4 nanostructured thin films: An effect of Gd doping concentrations

Cobalt oxide (Co3O4) thin films with 0, 1.0, 3.0 and 5.0 wt% Gd doping concentrations were fabricated on glass substrates by spray pyrolysis method. X-ray diffraction pattern (XRD) of as-deposited thin films confirm spinel structure growth oriented along (311) plane. Crystallite sizes of the grown films decreases with the increase in Gd doping concentrations and found in range of ∼17.7–7.2 nm. Raman investigation of films further approves spinel growth of cobalt oxide films. Surface morphology of pure and Gd: Co3O4 thin films were analyzed using field emission scanning electron microscopy (FESEM) with round shape particles at nanoscale. Chemical compositions, elements, and their stoichiometry were observed by energy dispersive spectra (EDX). Tauc's plots of films clearly shows two direct optical band gaps, (1) in the range of 1.49–1.52 eV and (2) in the range of 2.01 eV–2.58 eV respectively. A significant impact of Gd doping was observed on second optical band gaps, which increases with Gd contents. Room temperature (RT) dependent photoluminescence (PL) spectra of the deposited films showed that emission peaks at 363, and 753 nm under excitation wavelength of 240 and 500 nm respectively. The third order nonlinear optical susceptibility χ(3) and nonlinear refractive n(2) which were calculated and found in range 4.46 × 10−13- 2.25 × 10−10 esu and 1.01 × 10−10-2.39 × 10−9 esu., respectively.

Dynamic electric-field-induced magnetic effects in cobalt oxide thin films: towards magneto-ionic synapses

Voltage control of magnetism via electric-field-driven ion migration (magneto-ionics) has generated intense interest due to its potential to greatly reduce heat dissipation in a wide range of information technology devices, such as magnetic memories, spintronic systems or artificial neural networks. Among other effects, oxygen ion migration in transition-metal-oxide thin films can lead to the generation or full suppression of controlled amounts of ferromagnetism ('ON-OFF' magnetic transitions) in a non-volatile and fully reversible manner. However, oxygen magneto-ionic rates at room temperature are generally considered too slow for industrial applications. Here, we demonstrate that sub-second ON-OFF transitions in electrolyte-gated paramagnetic cobalt oxide films can be achieved by drastically reducing the film thickness from >200 nm down to 5 nm. Remarkably, cumulative magneto-ionic effects can be generated by applying voltage pulses at frequencies as high as 100 Hz. Neuromorphic-like dynamic effects occur at these frequencies, including potentiation (cumulative magnetization increase), depression (i.e., partial recovery of magnetization with time), threshold activation, and spike time-dependent magnetic plasticity (learning and forgetting capabilities), mimicking many of the biological synapse functions. The systems under investigation show features that could be useful for the design of artificial neural networks whose magnetic properties would be governed with voltage.

Electrical and optical properties of cobalt oxide thin films, prepared by ion-beam sputtering

Optical and electrical properties of cobalt oxide thin films obtained by ion-beam sputtering in argon atmosphere and argon with the addition of oxygen (PAr=1.1·10-5 Torr) has been investigated in the work. Optical properties investigations showed that, for films of cobalt oxide obtained in argon atmosphere, the optical band gap is independent of the film thickness and is 3.24 eV, which is in the range of given in the literature for the CoO phase values. For cobalt oxide films obtained in mixed atmosphere of argon with the addition of oxygen, two direct optical transitions with energies of 1.45 and 2.1 eV were detected. The presence of two direct allowed optical transitions is associated with the variable valence of cobalt in the Co3O4 compound and the presence of two valence states Co2+ and Co3+. The dependences of specific electrical conductivity of the synthesized films on the magnitude of the electric field were studied. It was found that for all investigated samples, the electrical conductivity does not depend on the electric field strength up to the value of E=106 V/m. The nonlinearity of the dependence of specific electrical conductivity of the synthesized films on electric field strength at E>106 V/m is discussed in terms of the hopping conductivity model and the trap ionization model described by the Poole?Frenkel effect. Keywords: oxide semiconductors, optical absorption coefficient, electrical conductivity, strong electric fields.

Электрические и оптические свойства тонких пленок оксида кобальта, полученных методом ионно-лучевого распыления

Optical and electrical properties of cobalt oxide thin films obtained by ion-beam sputtering in argon atmosphere and argon with the addition of oxygen (PAr = 1.1∙10-5 Torr) has been investigated in the work. Optical properties investigations showed that, for films of cobalt oxide obtained in argon atmosphere, the optical band gap is independent of the film thickness and is 3.24 eV, which is in the range of given in the literature for the CoO phase values. For cobalt oxide films obtained in mixed atmosphere of argon with the addition of oxygen, two direct optical transitions with energies of 1.45 and 2.1 eV were detected. The presence of two direct allowed optical transitions is associated with the variable valence of cobalt in the Co3O4 compound and the presence of two valence states Co2+ and Co3+. The dependences of specific electrical conductivity of the synthesized films on the magnitude of the electric field were studied. It was found that for all investigated samples, the electrical conductivity does not depend on the electric field strength up to the value of E = 106 V/m. The nonlinearity of the dependence of specific electrical conductivity of the synthesized films on electric field strength at E > 106 V/m is discussed in terms of the hopping conductivity model and the trap ionization model described by the Poole–Frenkel effect.