Chemical Composition Of Thin Films Research Articles

Effect of Chlorine Inclusion in Wide Band Gap FAPbBr3 Perovskites

AbstractWide bandgap perovskites have recently gained attention owing to their physical properties, versatility, and potential in various optoelectronic devices including LEDs, detectors, and building‐integrated photovoltaics (BIPV). However, BIPV materials must meet conflicting requirements, necessitating high performance, high transparency in the visible spectrum and color neutrality. This study investigates the controlled addition of chlorine in FAPb(Br1‐xClx)3 perovskites to achieve band gaps exceeding 2.4 eV. Increasing chlorine content from xCl = 0.00 to xCl = 0.25 widens the band gap from 2.37 to 2.52 eV, effectively improving the visible light transparency. Advanced characterization techniques including X‐ray diffraction, synchrotron radiation photoelectron spectroscopy, photoluminescence imaging, and fast transient absorption spectroscopy, complemented by density functional theory, reveal insights into absorption properties, electronic structure, and ultrafast recombination dynamics as a function of the thin film chemical composition. Furthermore, this study evaluates energetic disorder, carrier recombination rates, and non‐radiative losses for different compositions by extracting quantitative parameters such as Urbach energy and quasi‐Fermi level splitting, offering novel insights and guidelines for the design and optimization of emerging photovoltaic (PV) materials. Optimal PV performance metrics are achieved with a wide bandgap bromine perovskite containing 14% chlorine, striking a balance between morphology, transparency, and voltage losses.

Structural and thermal study of CuInSe2 films

Ternary copper indium Di-selenide (CISe) thin film has been deposited by spin-coating on non-conducting glass slide substrates and a solution prepared by the sol-gel process. At room temperature, correspondingly, CuCl2·2H2O, InCl3·3H2O, and H2SeO3 were employed as precursor source chemicals for Cu, In, and Se ions. The dark brown films adhered effectively to the glass substrates. Energy dispersive X-ray analysis is utilized to assess the thin film's chemical composition, which revealed that the film was close to the stoichiometric ratio and proved the proper elemental composition. The thin film's tetragonal unit cell structure was validated by XRD analysis, and all of the derived lattice parameters (a = 5.8512 A and c = 11.7268 A) are excellent consistent with the previous results. Scherrer's formula yields a crystallite size of 5.94 nm. SEM microtopography of the film surface revealed that the film is homogeneous on the substrate surface, and AFM revealed that the film has a spike-like morphology. UV–Vis spectroscopy was performed in the 300–1400 nm region. The obtained values of the absorption coefficient and band gap are 1.2eV. The thermal analysis is carried out by TGA.

Tailoring of Multisource Deposition Conditions towards Required Chemical Composition of Thin Films.

The model to tailor the required chemical composition of thin films fabricated via multisource deposition, exploiting basic physicochemical constants of source materials, is developed. The model is experimentally verified for the two-source depositions of chalcogenide thin films from Ga–Sb–Te system (tie-lines GaSb–GaTe and GaSb–Te). The thin films are deposited by radiofrequency magnetron sputtering using GaSb, GaTe, and Te targets. Prepared thin films are characterized by means of energy dispersive X-ray analysis coupled with a scanning electron microscope to determine the chemical composition and by variable angle spectroscopic ellipsometry to establish film thickness. Good agreement between results of calculations and experimentally determined compositions of the co-deposited thin films is achieved for both the above-mentioned tie-lines. Moreover, in spite of all the applied simplifications, the proposed model is robust to be generally used for studies where the influence of thin film composition on their properties is investigated.

Laser ablation of Ga‐Sb‐Te thin films monitored with quadrupole ion trap time‐of‐flight mass spectrometry

AbstractLaser ablation of Ga‐Sb‐Te chalcogenide thin films prepared by radiofrequency magnetron co‐sputtering was monitored with quadrupole ion trap time‐of‐flight mass spectrometry (QIT‐TOF‐MS). The mass spectra of 11 thin films of various compositions (Ga: 0–53.1, Sb: 0–52.0, and Te: 0–100.0 at. %) were recorded. Several series of unary (Gax, Sby, and Tez) binary (GaxSby, GaxTez, and SbyTez), and ternary GaxSbyTez clusters were identified in both positive and negative ion modes. Stoichiometry of observed clusters was determined. Up to 18 binary clusters (positively and negatively charged) were detected for thin film with low Sb content of 6.5 at. %. The highest number (4) of ternary clusters was observed for thin film with high Te content of 66.7 at. %. The number of generated clusters and their peaks intensity varied according to the chemical composition of thin films. Altogether, 41 clusters were detected. The laser ablation monitoring shows laser‐induced fragmentation of thin film structure. The relation of clusters stoichiometries to the chemical composition of thin films is discussed. The fragmentation can be diminished by covering a surface of thin films with paraffin's, glycerol, or trehalose sugar thin layers. The stoichiometry of generated clusters shows partial structural characterization of thin films.

Laser Induced Method to Produce Curcuminoid-Silanol Thin Films for Transdermal Patches Using Irradiation of Turmeric Target

A new possible method to produce a transdermal patch is proposed in this paper. The study refers to the pulsed laser deposition method (PLD) applied on turmeric target in order to obtain thin layers. Under high power laser irradiation of 532 nm wavelength, thin films containing curcuminoids were obtained on different substrates such as glass and quartz (laboratory investigation) and hemp fabric (practical application). Compared FTIR, SEM-EDS and LIF analyses proved that the obtained thin film chemical composition is mainly demethoxycurcumin and bisdemethoxycurcumin which is evidence that most of the curcumin from turmeric has been demethixylated during laser ablation. Silanol groups with known role into dermal reconstruction are evidenced in both turmeric target and curcuminoid thin films. UV–VIS reflection spectra show the same characteristics for all the curcuminoid thin films, indicating that the method is reproducible. The method proves to be successful for producing a composite material, namely curcuminoid transdermal patch with silanol groups, using directly turmeric as target in the thin film deposited by pulsed laser technique. Double layered patch curcuminoid—silver was produced under this study, proving compatibility between the two deposited layers. The silver layer added on curcuminoid-silanol layer aimed to increase antiseptic properties to the transdermal patch.

ZrCuAg Thin-Film Metallic Glasses: Toward Biostatic Durable Advanced Surfaces.

A combinatorial approach has served as a high-throughput strategy to identify compositional windows with optimized desired properties. Here, ZrCuAg thin-film metallic glasses were deposited by DC magnetron sputtering. For the purpose of using these coatings as biomedical surfaces, their durability in terms of mechanical and physicochemical properties as well as antibacterial properties were characterized. The effect of the chemical composition of thin films was studied. In particular, two key parameters were highlighted: the atomic ratio of Zr/Cu (with three values of 65/35, 50/50, and 35/65) and the silver content (from 1 to 16 at. %). All thin films are XRD amorphous and exhibit a typical veinlike pattern, which is characteristic of metallic glasses. They also show a dense and smooth surface and a hydrophobic behavior. Mechanical properties are found to be deeply influenced by the Zr/Cu ratio and the atomic structure. Although a low Zr/Cu ratio and/or a high silver content is detrimental to corrosion behavior, it favors the bactericidal effect of thin films. For all Zr/Cu ratios, ZrCuAg thin-film metallic glasses with silver contents higher than 12 at % are fully bactericidal. For lower silver contents, the bactericidal effect progressively decreases, which paves the way for a biostatic behavior of these surfaces.

Creation of ultrathin niobium nitride films at temperatures less than 100 °C

Thin NbN films were synthesized by a method of magnetron sputtering of solid Nb targets by nitrogen ions at temperatures less than 100 °C on substrates of the sapphire. The dependences of electrical resistance of films on the temperature in range 4.2 K – 300 K were measured. Volt-ampere characteristics and critical current density vs film thickness of films were made at a temperature of 4.2 K. The microstructure and film-depth chemical composition of thin films were investigated by analytical methods of the transmission electronic microscopy (HRTEM, EELS) on a cross-section samples made by the FIB technique. HRTEM and EELS study showed the Nb0.84N phase and poly-crystal structure of niobium nitride films. It was found that the critical current density falls down by an order of magnitude when the film thickness was less than 4 nanometers.

The tuning of electrical performance of Au/(CuO:La)/n-Si photodiode with La doping

In this study, CuO thin films are grown by spin coating method as a function of La doping on n-Si substrates. The morphological properties of thin films have been analyzed by AFM images, and it has been observed that the roughness of thin films have been decreased with increasing La dopant concentration. The surface topography and chemical composition of thin films have been studied by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), respectively. Then, the electrical characteristics of the fabricated heterostructures have been measured and analyzed under dark and illumination condition. All diodes show rectification behavior and sensitivity to light. It has been observed that the series resistance and ideality factor values, which are among the basic parameters of the diodes, have been improved by La content. Detailed examination of the photoelectrical properties of photodetectors has revealed that the photoresponsivity and detectivity of Au/(CuO:La)/n-Si have been significantly enhanced compared to the photodetector without La doped CuO. Results indicated that all structural and electrical parameters strongly depended on lanthanum concentration.

Unfolding the Influence of Metal Doping on Properties of CsPbI3 Perovskite

AbstractLow‐temperature α‐phase stabilization using HI or zwitterions in cesium lead iodide (CsPbI3) endures the metastable phase properties but is thermally unstable. Doping with a small amount of heterovalent metals (i.e., Bi3+, Sb3+) in CsPbI3 has been assumed to stabilize the α‐phase, while here this assumption is challenged. It is demonstrated that heterovalent metal ion doping stabilizes β‐CsPbI3 at low temperatures without replacing the Pb2+ cations, while divalent cations (i.e., Ba2+, Sr2+, and Sn2+) doping stabilizes the α‐CsPbI3 by replacing the Pb2+ cations. This finding is demonstrated by both theoretical and experimental results. It is also found that the divalent cations stabilize α‐CsPbI3 films, making thermally stable at high temperatures, whereas heterovalent metal‐doping stabilizes β‐CsPbI3 films, making metastable. The doping influence on crystal grains and the chemical composition of thin films is discussed. In particular, the charge dissociation kinetics for the Sr doped thin film are much enhanced than α‐CsPbI3 and Ba doped thin films, also the initial results of the fabricated perovskite red‐light‐emmiting diode suggests that the Sr‐doped thin films would be more suitable for the device fabrication. These findings will guide a way for further development in thermally and air‐stable optoelectronic devices.

Electrodeposition of Iridium-Nickel Thin Films on Copper Foam: Effects of Loading and Solution Temperature on Hydrogen Evolution Reaction Performance of Electrocatalyst in Alkaline Water

Developing novel hydrogen evolution reaction (HER) catalysts with high activity, high stability and low cost is of great importance for the applications of hydrogen energy. In this work, iridium-nickel thin films were electrodeposited on a copper foam as electrocatalyst for HER, and electrodeposition mechanism of iridium-nickel film was studied. The morphology and chemical composition of thin films were determined by scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS), respectively. The electrocatalytic performances of the films were estimated by linear sweep voltammograms (LSV), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The results show that iridium-nickel thin films were attached to the substrate of porous structure and hollow topography. The deposition of nickel was preferable in the electrolyte without the addition of additives, and the iridium-nickel thin film was alloyed, resulting in a high deposition rate for Ir42Ni58 thin film, and subsequently an increase of iridium content in the thin films of Ir80Ni20 and Ir88Ni12. Iridium-nickel thin films with Tafel slopes of 40–49 mV dec–1 exhibited highly efficient electrocatalytic activity for HER. The electrocatalytic activity of iridium-nickel thin films showed a loading dependence. As the solution temperature increased from 20°C to 60°C, the hydrogen evolution performance of iridium-nickel thin films improved. The apparent activation energy value of Ir88Ni12 film was 7.1 kJ mol–1. Long-term hydrogen evolution tests exhibited excellent electrocatalytic stability in alkaline solution.

Copper Sulfate Pentahydrate Target Behavior During Pulsed Laser Deposition to Produce Dichroic Coatings for Beam Splitters

Copper sulfate pentahydrate (CuSO4·5H2O) used as target in the pulsed laser deposition (PLD) process led to producing thin films with dichroic properties. The coatings were applied on glass slab and hemp fabrics. Investigation of CuSO4·5H2O transformation during ablation and deposition based on FTIR analysis showed that the thin film chemical composition is a mixture of different products resulted from CuSO4·5H2O dehydration and decomposition, followed by melting and vaporization of the CuO and recombination of the different species in the plasma of ablation. Simulation in COMSOL of the CuSO4·5H2O laser heating anticipates the processes and phenomena to be expected during PLD. Optical properties of the thin films are investigated in UV-Vis as reflecting properties and by laser induced fluorescence (LIF). Applications are considered for dichroic plate beamsplitters, as well as others. Dichroic beamsplitters have a large range of applications among which they are useful for combining / splitting laser beams of different color. When the chemical composition provides also electrical conductivity specific properties, the coating may bring more value to the new device or material. In order to ascertain whether a dichroic system can be produced one way or the other achieving at the same time specific characteristics, it is important to understand the physico – chemical processes behind that. With this study, we determine the method to produce dichroic coatings on glass and on hemp fabric, looking at the same time into the mechanism that leads to the result.

Influence of the magnetic field on bandgap and chemical composition of zinc thin films prepared by sparking discharge process

We examine the influence of the magnetic field on the chemical reaction of nitrogen and carbon dioxide in sparking electric discharge of zinc wires. Samples are prepared on Indium Tin Oxide (ITO) and quartz substrates in the form of thin films at 0 T, 0.2 T and 0.4 T. Different chemical composition of thin-films prepared by sparking discharge was obtained and verified by XPS, Raman and Cyclic voltammetry. Carbon dioxide conversion to carbonates was observed for zinc sparked in CO2 and nitrogen affecting crystallization of thin films was confirmed by XRD. Synthesis route for thin-film preparation used in this study is electric sparking discharge, convenient for fast ionization of metal and gasses. Band gap energy of thin films prepared by this method was starting from 2.81 eV and 4.24 eV, with the lowest band gaps prepared on ITO in 0.4 T. Differential Mobility Analysis (DMA) indicates smaller particles are fabricated by discharging zinc wires in a higher magnetic field. Nitridification of zinc nanoparticles occurred on 0.2 Tesla magnetic field strength and it was detectable even after XPS ion gun etching. Carbonation and nitridification of zinc thin films by sparking wires inside the magnetic field to observe the effect of the magnetic field on bandgap and chemical composition are confirmed by XPS.

Quantifying the Composition of Methylammonium Lead Iodide Perovskite Thin Films with Infrared Spectroscopy

Lead halide perovskites are generally formed from a reaction of the lead halide salt with the halide salt of the A cation. The effects of varying film compositions as result of nonstoichiometric precursor ratios on electronic properties of halide perovskites are currently under debate. It is imperative, but experimentally challenging, to determine the chemical composition of thin films as a function of precursor ratio for a full understanding of the effect. Herein we report a precise quantification of the methylammonium (MA) content in differently fabricated films of MAPbI3 via infrared spectroscopy. We compare the thin film data to the first high-quality dielectric function obtained from single crystals with IR ellipsometry. For spin-coated samples, we find that the MAI/PbI2 ratio in solution has an effect on the MA content in the resulting thin films, which is in the range of 77–106% compared to single crystals. For coevaporated samples, we show that a very similar range of MA content variation is accessible. Interestingly, coevaporated films prepared like those for high-efficiency solar cells have a significantly lower MA content than that of single crystals.

Technological Methods of Forming Thin Semiconductor Layers. Part 1

The review and analysis of the basic technological methods of formation of thin layers of semiconductor materials is presented. The timeframe for the occurrence of thin film technologies and the main centers of their localization are specified. It is shown that nowadays structure, properties and basic methods of obtaining thin films sufficiently well studied for not only simple but also complex, multi-component inorganic semiconductor materials, new areas of application and increase of requirements to the operational characteristics of devices on their basis require improvement of existing technologies and development of new methods for their synthesis, which involves a detailed analysis of the known, and the search for new, progressive methods of preparation. Due to the fact that the main methods for obtaining thin films of inorganic semiconductor materials are vacuum condensation and chemical precipitation, the first part of the review describes the methods of their vacuum application, in particular, thermal spraying in an open vacuum. It is shown that the most common way of obtaining thin films is the thermal spraying under resistive heating of the evaporator with the source material.We analyze the special structural and technological changes and improvement of traditional methods and systems of thermal spraying, which allow to equalize the ratio of the chemical composition of thin films and the source material, improve the stoichiometry of condensates, and ensure their homogeneity.The designs of thermal evaporators with resistive heating of crucibles in an open vacuum with sublimation or evaporation of one and two substances are presented. It is shown how these types of evaporators exclude the transfer of solid particles into evaporating or sublimation into the vapor phase and eliminate direct vapor deposition on the condensation surface, which more or less protects against heterogeneous condensate inclusions.It is shown that the methods analyzed or their modifications are nowadays the necessary means for the creation of thin-film semiconductor structures with predetermined properties, while vacuum deposition, in particular, traditional and modified thermal spraying in a vacuum due to its simplicity(but at the same time its ability to effectively control a large the number of technological factors and create the necessary conditions for the growth of condensates) remains one of the most common ways of obtaining thin films, including inorganic semiconductors.

Correlative Experimental and Theoretical Investigation of the Angle-Resolved Composition Evolution of Thin Films Sputtered from a Compound Mo2BC Target

The angle-resolved composition evolution of Mo-B-C thin films deposited from a Mo2BC compound target was investigated experimentally and theoretically. Depositions were carried out by direct current magnetron sputtering (DCMS) in a pressure range from 0.09 to 0.98 Pa in Ar and Kr. The substrates were placed at specific angles α with respect to the target normal from 0 to ±67.5°. A model based on TRIDYN and SIMTRA was used to calculate the influence of the sputtering gas on the angular distribution function of the sputtered species at the target, their transport through the gas phase, and film composition. Experimental pressure- and sputtering gas-dependent thin film chemical composition data are in good agreement with simulated angle-resolved film composition data. In Ar, the pressure-induced film composition variations at a particular α are within the error of the EDX measurements. On the contrary, an order of magnitude increase in Kr pressure results in an increase of the Mo concentration measured at α = 0° from 36 at.% to 43 at.%. It is shown that the mass ratio between sputtering gas and sputtered species defines the scattering angle within the collision cascades in the target, as well as for the collisions in the gas phase, which in turn defines the angle- and pressure-dependent film compositions.

Investigation of work function and chemical composition of thin films of borides and nitrides

Thin films of various borides, nitrides, and barium fluorides were tentatively deposited by pulsed laser deposition and by magnetron sputtering in order to develop the components of thermionic‐photovoltaic devices for the high‐temperature thermal to electrical conversion by solid state. To improve the device performance, the materials characterized by a low work function were selected. In the present work, the chemical composition and work function of obtained films were investigated by X‐ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy techniques. The values of work function were determined from the cut‐off in the He I valence band spectra. Different films were compared and estimated on the basis of X‐ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy results.

Thin insulating film deposition on copper by atmospheric‐pressure plasmas

Long‐time partial discharge (PD) is regarded as one of the main reasons for the insulation failure of high‐voltage cables. In this work, we report on the application of atmospheric pressure plasma to deposit siloxane film on copper to avoid PDs. The dielectric barrier discharge (DBD) plasma is driven by AC power supply, with tetraethoxysilane (TEOS), argon, and oxygen mixture as the source gas. The effect of oxygen gas flow rate on the thin film surface morphology, chemical composition, and electrical properties is studied systematically. Our results show that the stability of the plasma deteriorated, when the oxygen flow rate exceeded 10 sccm. The addition of oxygen in the source gas induced a high oxidation level of deposited thin film. The chemical composition of thin film was in the form of SiOx (x = 1.9) with 10 sccm oxygen compared to SiOx (x = 1.2), when deposited in the absence of oxygen. Additionally, the optimal thin film with good stability was obtained with the surface resistivity 1.1 × 1011 Ω, when deposited in the absence of oxygen. The corresponding relative permittivity of the deposited thin film is 2.9. The simulation results demonstrated that the electric field distortion was weaken after the film deposition, which reduced the probability of PD to occur.

PEALD grown high-k ZrO2 thin films on SiC group IV compound semiconductor

The study of ZrO2 thin films on SiC group IV compound semiconductor has been studied as a high mobility substrates. The ZrO2 thin films were deposited using the Plasma Enhanced Atomic Layer Deposition System. The thickness of the thin films were measured using ellipsometer and found to be 5.47 nm. The deposited ZrO2 thin films were post deposition annealed in rapid thermal annealing chamber at temperature of 400°С. The atomic force microscopy and X-гау photoelectron spectroscopy has been carried out to study the surface topography, roughness and chemical composition of thin film, respectively.

PEALD grown high-k ZrO-=SUB=-2-=/SUB=- thin films on SiC group IV compound semiconductor

The study of ZrO2 thin films on SiC group IV compound semiconductor has been studied as a high mobility substrates. The ZrO2 thin films were deposited using the Plasma Enhanced Atomic Layer Deposition System. The thickness of the thin films were measured using ellipsometer and found to be 5.47 nm. The deposited ZrO2 thin films were post deposited annealed in rapid thermal annealing chamber at temperature of 400oC. The atomic force microscopy and x-ray photoelectron spectroscopy has been carried out to study the surface topography and roughness and chemical composition of thin film respectively. DOI: 10.21883/FTP.2017.01.8125

Preparation and surface characterization of nanodisk/nanoflower-structured gallium-doped zinc oxide as a catalyst for sensor applications

Nanostructured gallium-doped zinc oxide (GZO) thin films were fabricated on piezoelectric substrates. The GZO thin films with nanodisk/nanoflower morphologies were prepared by a simple spin-coating process followed by one-step hydrothermal treatment. Addition of polymer during hydrothermal treatment resulted in nanodisk and nanoflower morphologies. The morphology, microstructure and chemical composition of thin films prepared under different conditions were examined by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and Raman spectroscopy. The XRD and FE-SEM investigations confirmed that the GZO nanodisks, nanorods and nanoflowers formed on the AlN/Si substrates were all wurtzite phase. Green fluorescent protein (GFP) was immobilized on the as-synthesized GZO nanostructured materials by a dipping process. Atomic force microscopy (AFM) and fluorescence spectroscopy measurements were conducted to confirm the surface binding nature of GFP on the GZO nanostructures to determine their suitability for use in sensor applications and bioimaging techniques. Trace-level addition of GFP to the GZO nanostructures resulted in a fluorescence response, revealing good activity for ultraviolet light sensor applications.