Electrical Properties Of Thin Films Research Articles

Structural, optical, and electrical properties of e-beam deposited metamaterials of granular CdSe thin films on glass substrates with a thin buffer layer of HfO2 dielectric

Structural, optical, and electrical properties of granular thin films of CdSe deposited on HfO2 dielectric layer are reported. The thin films were deposited on fluorine-doped tin oxide (FTO) coated glass substrates by e-beam evaporation technique. Structural analysis revealed the amorphous nature of the HfO2, whereas wurtzite type hexagonal crystal structure was observed in the CdSe thin films. Microstructural analysis showed the granular nature of both the deposited layers. The optical and electrical properties of the thin films were studied in detail. The dielectric properties of the deposited layers were studied in correlation with their microstructure. The appearance of negative permittivity (NP) in the films indicates towards metamaterial type characteristics which has various potential applications viz. high permittivity capacitors, microwave filters, coil free resonators, and thin film transistors (TFTs).

Structural, Electrical and Optical Properties of Graphite Films are Drawn with Pencils of Different Hardness

The paper presents the results of studying the structural, optical and electrical properties of thin films of graphite depending on the hardness of the rods (2H, H, HB, B and 2B) obtained by the "Pencil-on-semiconductor" method. Such studies are of great importance for the further development of highly efficient devices based on heterojunctions for electronics and optoelectronics. Typical images of the surface formed by reflected electrons (BSE) were obtained using a scanning electron microscope and shown at three magnifications (100x, 500x and 1000x). Since the cores of the studied pencils consist of mixtures of clay and graphite, a more detailed analysis of the elements that make up the cores was conducted. EDS analysis showed that the main components of the studied rods are purified graphite powder, as well as O, Al and Si, which are part of kaolin whose formula is H4Al2Si2O9, or Al2O3 • 2SiO2 • 2H2O - the main component of ordinary clay. The elemental composition of the microvolume of the studied samples was also determined. Regardless of the error that occurs when determining the composition of C and O (~ 12%), it can be argued that there is still a regularity between the graphite content and the hardness of the pencil. That is, the higher the graphite content, the softer the rod. The thickness of the graphite films was measured using the MII-4 interferometer according to the standard method. The average thickness of all investigated films was ~ 150 nm since the thickness of the films obtained by this method is mainly determined by the roughness of the surface of the salt substrate. Drawn graphite films have a higher resistivity than bulk samples (pencil rods) from which they were made. The resistance of the films increases with an increase in the hardness of pencils, due to an increase in the number of clay impurities in graphite, which is a dielectric. It was found that an increase in stick hardness leads to an increase in transmission.

Structure Modification, Evolution, and Compositional Changes of Highly Conductive La:BaSnO3 Thin Films Annealed in Vacuum and Air Atmosphere.

Perovskite-type La:BaSnO3 (LBSO) has been drawing considerable attention due to its high electron mobility and optical transparency. Its thin film electrical properties, however, remain inferior to those of single crystals. This work investigates the thermal post-treatment process of films deposited using the metalorganic chemical vapor deposition method to improve the electrical properties of different stoichiometry films, and demonstrates the modification of thin film’s structural properties using short and excessive annealing durations in vacuum conditions. Using vacuum post-treatment, we demonstrate the improvement of electrical properties in Ba-rich, near-stoichiometric, and Sn-rich samples with a maximum electron mobility of 116 cm2V−1s−1 at r.t. However, the improvement of electrical properties causes surface morphology and internal structural changes, which depend on thin film composition. At temperatures of 900 °C–1400 °C the volatile nature of LBSO constituting elements is described, which reveals possible deterioration mechanisms of thin LBSO air. At higher than 1200 °C, LBSO film’s decomposition rate increases exponentially. Thin film structure evolution and previously unreported decomposition is demonstrated by Ba and La diffusion to the substrate, and by evaporation of SnO-SnOx species.

Effect of Annealing and Ion Beam Irradiation on AC Electrical Properties for Gold Sputtered PM-355

Deposition of different gold thickness on PM-355 cleaned by ethanol forming thin films using magnetron sputtering. Gold layer with thickness 300, 400, 500, 700, 1000, 1300, and 1500 nm were deposited to prepare Au / PM-355 thin films. Then, ac electrical properties response of thin films for a wide frequency range 20Hz - 5MHz were measured at roomtemperature. Meanwhile, the measurements of ac conductivity, dielectric constant, and dielectric loss factor were plotted at different frequencies to determine the optimum thickness. Hence, the comparison was done between optimum Au thickness thin films cleaned by two organic solvents and ethanol before annealing at different frequencies. Also, study the effect of annealing and ion beam that extracted radially from conical anode and disc cathode ion source on optimum Au thickness thin film electrical properties. It is found that the annealing increases both dielectric constant, dielectric loss, and ac conductivity of optimum Au thin film at different frequencies. Despite, the nitrogen ion beam effected on these thin films by decreasing the dielectric constant and ac conductivity for all thin films except the chloroform one. Finally, study the comparison between the annealing and followed by ion irradiation thin films. It is noticed the decrease in ac electrical conductivity and dielectric constant at different frequencies.

Study and Investigation of the Effects of the OTA Technique on the Physical Properties of the ZnO Thin Films Prepared by PLD

The polycrystalline thin films were deposited on glass substrate at room temperature by pulsed laser deposition PLD technique. The effects of annealing treatment by used the Oil Thermal Annealing (OTA) process on the structural, optical and electrical properties of ZnO thin film films were investigated. The film structure was investigated by X-ray diffraction to indicate that the heat treatment after the OTA process gives the optimized condition of crystalline. The transmission spectrum of the film was measured by UV-V is spectrophotometer, and the Urbach energy and forbidden band width were calculated. The surface topography of the film was observed by scanning electron microscopy (SEM) image of the ZnO thin film at the OTA process shows the changes in the shape and size of the grains. The atomic force microscopy (AFM) effect of heat treatment was demonstrated by the change in the surface roughness of the ZnO thin film. The electrical properties of thin film were optioned by Hall Effect technique. That these improvements in the ZnO thin film physical properties were annealing temperatures by OTA at 150 °C, 200 °C, 250 °C and 300 °C.

Effect of complexing agent and deposition time on structural, morphological, optical and electrical properties of cuprous oxide thin films prepared by chemical bath deposition

Cuprous oxide (Cu2O) thin films were synthesized on corning glass substrates by chemical bath deposition. The influence of complexing agent and deposition time was investigated on the structural, morphological, optical and electrical properties of the thin films. It was found that the complexing agent triethanolamine (TEA) plays a key role not only promoting the adherence and crystallinity of Cu2O, but also controlling the thickness by regulating the release of Cu+ ions. The increase of complexing agent and long deposition times produce thicker films. It was found that thickness has a strong relation with preferential orientation. Thinner films (50–100 nm) present orientation along the (111) plane, which changes to the (200) plane as the thickness increases. Electrical conductivity decreases as the film becomes thicker, registering values of 101 (ohm*cm)−1 and 10−4 (ohm*cm)−1 for 50 and 920 nm respectively. The structural defects, mainly Cu vacancies, are responsible for the variations in electrical properties and can be related to the Urbach energy (EU) disorder. It was observed a decrease in EU when preferential orientation changes from (111) plane to (200) plane, which means less disorder and consequently less defects, which enhances the resistivity.

Rapid Degradation of the Electrical Properties of 2D MoS2 Thin Films under Long-Term Ambient Exposure.

The MoS2 thin film has attracted a lot of attention due to its potential applications in flexible electronics, sensors, catalysis, and heterostructures. Understanding the effect of long-term ambient exposure on the electrical properties of the thin film is important for achieving many overreaching goals of this material. Here, we report for the first time a systematic study of electrical property variation and stability of MoS2 thin films under ambient exposure of up to a year. The MoS2 thin films were grown via the sulfurization of 6 nm thick molybdenum films. We found that the resistance of the samples increases by 114% just in 4 weeks and 430% in 4 months and they become fully insulated in a year of ambient exposure. The dual-sweep current–voltage (I–V) characteristic shows hysteretic behavior for a 4-month-old sample which further exhibits pronounced nonlinear I–V curves and hysteretic behavior after 8 months. The X-ray photoelectron spectroscopy measurements show that the MoS2 thin film gradually oxidizes and 13.1% of MoO3 and 11.8% oxide of sulfur were formed in 4 months, which further increased to 23.1 and 12.7% in a year, respectively. The oxide of the sulfur peak was not reported in any previous stability studies of exfoliated and chemical vapor deposition-grown MoS2, suggesting that the origin of this peak is related to the distinct crystallinity of the MoS2 thin film due to its smaller grain sizes, abundant grain boundaries, and exposed edges. Raman studies show the broadening of E2g1 and A1g peaks with increasing exposure time, suggesting an increase in the disorder in MoS2. It is also found that coating the MoS2 thin film with polymethylmethacrylate can effectively prevent the electrical property degradation, showing only a 6% increase in resistance in 4 months and 40% over a year of ambient exposure.

Properties of Barium Cerate-Zirconate Thin Films

In this work, we review several experimental results showing the electrical properties of barium cerate-zirconate thin films and discuss them in view of the possible influence of various factors on their properties. Most of the presented Ba(Ce, Zr, Y)O3 thin films were formed by the pulsed laser deposition (PLD) technique, however thin films prepared using other methods, like RF magnetron sputtering, electron-beam deposition, powder aerosol deposition (PAD), atomic layer deposition (ALD) and spray deposition are also reported. The electrical properties of the thin films strongly depend on the film microstructure. The influence of the interface layers, space-charge layers, and strain-modified layers on the total conductivity is also essential but in many cases is weaker.

Theoretical investigation of diffusion and electrical properties of yttria-stabilized zirconia thin film

The diffusion and electrical properties of yttria-stabilized zirconia (YSZ) thin film with fluorite structure are theoretically investigated using the statistical moment method. Our results show the lattice expansion with the thickness reduction and the diffusion coefficient and ionic conductivity of YSZ thin film with thickness ranging from 10 nm to 20 nm are more than one to two orders of magnitude enhancement in comparison with those of bulk YSZ. The thickness dependence of the lattice constant, diffusion coefficient, and ionic conductivity is attributed to the interaction potential and anharmonicity lattice vibrations occurred at the external layers. The influence of the external layers on the diffusion and electrical properties of thin film decreases with the increasing thickness and this influence is negligible with the thickness exceeding 1000 nm. The roles of substrate and grain boundary are ignored in the present study. Our study contributes to the experiments related to the effect of the external layers on the diffusion and electrical properties of YSZ thin film.

Bandgap tuning of optical and electrical properties of zinc selenide

Zinc Selenide (ZnSe) as an important II-VI semiconductor and one of the first semiconductors discovered with a band gap of around 2.7 eV at 25 °C. ZnSe thin films have been deposited by e-beam evaporation method with different thicknesses from 50 nm to 150 nm and effects of annealing temperature on optical and electrical properties of thin films have been investigated at room temperature (RT), 1000C and 2000C. It has been found that the energy bandgap of semiconductor thin films tend to decrease as the temperature increases. Optical properties of the synthesized films were investigated by UV-VIS spectrometer in the wavelength range of 400-1000 nm. Energy band gap of films were calculated and variation due to variation in the thickness were observed. The least band gap value was found to be 1.92 eV for 150 nm thin at 2000C.The band gap results show the semiconducting nature of films grown. XRD technique was used to study the structural properties and the Hall measurement and I-V characteristics were used to study the electrical properties of the thin films. Hall characteristic of the ZnSe thin films for 150 nm at room temperature show that the material has p-type semiconducting nature which remains same if annealed to 2000C.

Pulsed laser modification of layered B-C and mixed BCx films on sapphire substrate

The effect of pulsed laser annealing (PLA, i.e., action of nanosecond laser pulses in air atmosphere) on surface morphology, structure, chemical state, and electrical properties of thin films consisting of boron and carbon atoms was studied. The nanolayered В/С and mixed ВСx~3 thin film precursors (with a thickness ~110–140 nm) were created on sapphire substrates by using the pulsed laser deposition. Scanning electron microscopy and Raman scattering measurements indicate that the process of stratification of the multilayer B/C films dominated during PLA of the films. The outer layers were removed, and closer to the substrate, the B and C layers were preserved, and they were not mixed. For the mixed ВСх films deposited at elevated temperatures, the PLA treatment enhances ordering of initially amorphous film structure. At the stage of melting of these films, oxygen (from surrounded air) penetrated inside the top layer of the film leading to the formation of a multiphase structure from g-BCx and B-doped GO/rGO after solidification. Studies of the chemical state of elements in the irradiated film have shown that О atoms, which penetrated the under-surface layers of the film, facilitated the formation of new chemical bonds in the B–C–O system. The concentration of O atoms in the depth of the film could reach 8%. The preferential oxidation of boron in a homogeneous mixture of B–C–O atoms indicated that intercalation of carbon matrix could be due to the incorporation of not only O atoms, but also B–O molecules. The laser irradiated ВСх films have a relatively low resistivity (~1.6 mΩ·cm) and semi-metallic dependence on temperature in the range 4.2–300 К. The spatial distribution of conductivity zones after PLA has an irregular structure, and its pattern looks like sand dunes, indicating that the PLA treatment leads to mixing zones of high with those of lower conductivity. The contact-tip resistivity inside the areas of high conductivity of the ВСx/Al2O3 samples may be significantly lower than that of pure graphite.

Influence of light on electrophysical properties of thin films of mixed zinc and tin oxides

In this work, we studied structural and the electrical properties of thin films of mixed zinc and tin oxides obtained by low-temperature pyrolysis. XRD analysis shows that the obtained films contain phases of zinc oxide and tin dioxide and have nanocrystalline structure with crystallite size about 10-17 nm. A significant effect of daylight on the temperature dependences of the film resistance was established. The temperature dependences of the resistance of ZnO-SnO2 films, measured in the range from room temperature to 300 °C, show the difference between the heating and cooling curves, that can be explained by two competing processes - thermal activation mechanism of conductivity and adsorption-desorption of oxygen particles on the surface of the oxide film. Using the slope of the linear section on the plots, we calculated the activation energy of conductivity, which amount is 0.7 and 1.1 eV for the samples with the different Zn:Sn ratio.

Electrical and Structural properties of (ZnTiO3)/Epoxy System Nanocomposite Thin films

Spin coating technique using to prepare two layers of epoxy reinforced by weight (0Wt%,1Wt%,2Wt%,3Wt%,4Wt%) nano ZnTiO3additives uniform thin films with a fixed thickness of (0.7 ☐m) on glass floors at room temperature, dispersion and magnetic stirring techniques are used to prepare the nanocomposites thin films. The purpose of this study was to produce a new modified polymer (ZnTiO3/Epoxy) nanocomposite thin films then evaluate electrical and structural properties of these thin films. The electrical properties of thin films have a degree effect temperature on the resistance (R) of thin films within the range (303- 433) k or (30-160) C0. Electrical conductivity and activation energy of the thin film was calculated where the results indicate that there is a two activation energy and this means there is two mechanisms connection. It is also shown by measurements of the effect of the whole (ZnTiO3/Epoxy) nanocomposite thin films have a connection from the negative type (n-type). Stractural properties include XR-D and SEM. XRD, show crystal structure of zinc titanite (ZnTiO3) nano powder. Scanning electron microscopy SEM, show clearly analysis for different weight ratio affected thin films surfaces.

Growth and Characterization of Cu2MnSnS4 Thin Films Synthesized by Spray Pyrolysis under Air Atmosphere

The direct synthesis of chalcopyrite Cu2MnSnS4 (CMTS) thin films by a spray pyrolysis technique on glass substrates under oxidative conditions (ambient atmosphere and using compressed air as a carrier gas instead of nitrogen) was studied. The effect of the deposition temperature on the structural, chemical composition, and optical and electrical properties of thin films has been assessed. X-ray diffraction study reveals that the tetragonal stannite structure crystallizes with a [112] preferential orientation from 280 up to 360 °C, with its crystallinity correlated with the substrate temperature. However, in addition to its crystallization, traces of secondary phases are observed: a mixture of SnO and CuO at 360 °C prevails on the formation of CuS at 320 °C. Above 360 °C, the oxidant conditions combined with the loss in sulfur lead to the crystallization of only the tenorite CuO. The crystallization of sulfides by spray pyrolysis under air is possible only at relatively low deposition temperature for which the oxidation rate is inefficient compared to the sulfidation rate. Further optical studies of stannite films indicate a high absorption coefficient toward the visible range (>104 cm−1) and an optical band gap of about 1.64–1.85 eV, also depending on the substrate temperature. The CMTS thin films deposited below 360 °C exhibit a moderate electrical resistivity of about Ω·cm at room temperature. The properties of the stannite films synthesized using a spray pyrolysis technique in ambient air are comparable to those of films obtained by spray pyrolysis with nitrogen carrier gas despite the presence of oxides traces, an increase in the deposition temperature improving the microstructure, and its related optical and electrical properties.

Nanostructure morphology influences in electrical properties of titanium dioxide thin films

Abstract

Nanoscale mobility mapping in semiconducting polymer films

Local electrical properties of thin films of the polymer PTB7 are studied by conductive atomic force microscopy (C-AFM). Non-uniform nanoscale current distribution in the neat PTB7 film is revealed and connected with the existence of ordered PTB7 crystallites. The shape of local I-V curves is explained by the presence of space charge limited current. We modify an existing semi-empirical model for estimation of the nanoscale hole mobility from our experimental C-AFM measurements. The procedure of nanoscale charge mobility estimation was described and applied to the PTB7 films. The calculated average C-AFM hole mobility is in good agreement with macroscopic values reported for this material. Mapping of nanoscale hole mobility was achieved using the described procedure. Local mobility values, influenced by nanoscale structure, vary more than two times in value and have a root-mean-square value 0.22 × 10−8 m2/(Vs), which is almost 20% from average hole mobility.

Processing and Study of Optical and Electrical Properties of (Mg, Al) Co-Doped ZnO Thin Films Prepared by RF Magnetron Sputtering for Photovoltaic Application.

In this study, high transparent thin films were prepared by radio frequency (RF) magnetron sputtering from a conventional solid state target based on ZnO:MgO:Al2O3 (10:2 wt %) material. The films were deposited on glass and silicon substrates at the different working pressures of 0.21, 0.61, 0.83 and 1 Pa, 300 °C and 250 W of power. X-ray diffraction patterns (XRD), atomic force microscopy (AFM), UV-vis absorption and Hall effect measurements were used to evaluate the structural, optical, morphological and electrical properties of thin films as a function of the working pressure. The optical properties of the films, such as the refractive index, the extinction coefficient and the band gap energy were systematically studied. The optical band gap of thin films was estimated from the calculated absorption coefficient. That parameter, ranged from 3.921 to 3.655 eV, was hardly influenced by the working pressure. On the other hand, the lowest resistivity of 8.8 × 10−2 Ω cm−1 was achieved by the sample deposited at the lowest working pressure of 0.21 Pa. This film exhibited the best optoelectronic properties. All these data revealed that the prepared thin layers would offer a good capability to be used in photovoltaic applications.

Electrical Properties of Thin In2O3/C Films

We have studied the structure and electrical properties of thin films based on the In2O3 semiconductor and carbon, grown by atomic layer deposition using ion-beam sputtering. The structure of the resultant materials, formed during layer-by-layer growth of island layers, is made up of nanocrystalline In2O3 granules distributed at random over amorphous carbon. The electrical transport properties of the In2O3/C thin films depend on their thickness. In the temperature range 80–300 K, the dominant electrical transport mechanism in the In2O3/C thin films of thickness h 70 nm undergo a change from conduction associated with strong carrier localization to that due to the presence of percolation clusters formed by In2O3 nanocrystals, which shows up as a linear temperature dependence of conductivity, with a negative temperature coefficient.

Optical and Electrical Properties of Graphite Thin Films Prepared by Different Methods

The paper reports on the structural, optical and electrical properties of graphite thin films prepared by two methods: the vacuum-free method "Pencil-on-semiconductor" and via the electron beam evaporation. Graphite thin films prepared by the non-vacuum method has annealed at a temperature of 920K.The transmission spectra of the investigated graphite films and the electrical properties of these thin films were measured at T = 300 K. The value of the height of barriers Eb at the grain boundaries and the temperature dependence of the electrical conductivity in the range ln(σ·T1/2) = f(103/T) were determined, It is established that the height of the barrier at the grain boundaries for the drawn graphite films is Eb = 0.03 eV, for annealed Eb = 0.01 eV and for the graphite films deposited by the electron beam evaporation Eb = 0.04 eV, ie for annealed film the barrier height is the smallest. It is shown that graphite films deposited by the electron beam evaporation reveals the highest transmittance (T550 ≈ 60%), and the transmission of drawn films is the lowest, annealing leads to its increase. The minimum values ​​of transmission at a wavelength λ = 250nm are due to the scattering of light at the defects that are formed at the grain boundaries. Annealed graphite films have been found to possess the best structural perfection because they have the lowest resistivity compared to non-annealed films and electron-beam films and have the lowest barrier height. Simultaneous increase of transmission in the whole spectral range, increase of specific electrical conductivity and decrease of potential barrier at grain boundaries of the annealed drawn graphite film clearly indicate ordering of drawn graphite flakes transferred onto anew substrate, which led to the reduction of light scattering and the improvement of charge transport due to the larger area of ​​overlap between graphite flakes.

The influence of diameter of multiwalled carbon nanotubes on mechanical, optical and electrical properties of Langmuir-Schaefer films.

In this paper results of a study of mechanical, optical and electrical properties of thin films made of multiwall carbon nanotubes (MWCNT) of various types were reported. The MWCNT films were obtained on quartz substrates using the Langmuir-Schaefer (LS) method. A gradual increase in transmittance was recorded with decreasing diameters of MWCNT used. Moreover, a blue shift of the π-plasmon band position was observed with increasing MWCNT diameter. In all tested films, anisotropy of electrical surface resistivity was revealed, which was more pronounced for MWCNT of low diameters, except for the MWCNT sample of the smallest diameters. Results of oscillatory barrier measurements of various MWCNT films at the air water interface were used to calculate the complex compression and shear moduli. It is worth emphasizing that the values of these moduli were obtained for the first time for carbon nanotubes films. Moreover, the obtained results allowed identification of the main factor blocking the alignment process, which turned out to be the shear loss tangent.