Structural Properties Of Films Research Articles

Pea protein-p-coumaric acid conjugate-based antioxidant film: The relationship between protein structure and film properties after covalent bonding

In this study, pea protein isolates (PPI) have been used to make conjugates by covalent binding with p-coumaric acid (p-CA), and the effect of conjugation on PPI structural characteristics and the structural, optical, mechanical, and physicochemical properties of conjugate-based films were investigated. The conjugation with p-CA unfolds the tertiary structure of PPI and significantly reduces the surface charge. A tendency of aggregation with increasing p-CA addition was proposed. The conjugate-based films show stronger tensile strength (TS) and better water barrier properties than PPI-based films. However, no significant improvement of the elongation at break (EAB) and thermal stability was found for conjugate-based films. FTIR spectroscopic and zeta-potential analyses indicated that such improved film properties could be attributed to the enhancement of hydrogen bonds and weakening of electrostatic repulsion between conjugate-conjugate. Additionally, the conjugates impart the antioxidant activity to the films as confirmed by DPPH scavenging capacity. This study demonstrates the potential of using pea protein-phenolic acid conjugate to make PPI-based films with improved mechanical properties, water barrier properties, and antioxidant activity.

Ni-modified BaTiO3 film prepared by sol-gel with high energy storage performance

The development of lead-free dielectric capacitors with high recoverable energy storage density and high energy storage efficiency is important for improving the overall performance of electronic and power systems. BaTiO3 (BTO) is one of the most common ferroelectric materials and has attracted much attention for energy storage applications in the past decades due to its excellent dielectric and ferroelectric properties. However, high remnant polarization and low electrical breakdown strength of BTO limit its development in energy storage applications. Many efforts (e.g., elements doping, interface/heterostructure, etc.) have been made to improve the energy storage density of BTO thin films. In this paper, Ba1-xNixTiO3 thin films (x = 0, 0.02, 0.04, 0.06, 0.08; abbreviated as BNxT) were synthesized via sol-gel and spin-coated method. The effect of Ni doping on the structural, dielectric, ferroelectric and energy storage properties of BTO thin films has been studied. The results confirmed that with the increase of Ni doping, a second phase arises and the dielectric constant decreases. While appropriate Ni doping led to the improvement of the breakdown strength, further increase of Ni deteriorated the energy storage because of the high oxygen vacancy. Finally, optimized energy storage performance was obtained for BN0.04T thin film: dielectric constant of 401, dielectric loss of 0.002, recoverable energy density of 20.2 J/cm3 and energy storage efficiency of 83.6% at 965 kV/cm. Meanwhile, the remnant and maximum polarization of the films were 0.06 μC/cm2 and 50 μC/cm2, respectively. BN0.04T thin film has an excellent application prospect and is expected to appear as a component in the future composite energy storage film system.

Optimizing the optoelectronic properties of broadband FeS2/Si photodetectors via deposition temperature tuning in chemical bath deposition.

This study investigates the fabrication and characterization of n-FeS2/p-Si heterojunction photodetectors using chemical bath deposition (CBD) at deposition temperatures ranging from 50 °C to 80 °C. The impact of temperature on the structural, morphological, and optical properties of FeS2 thin films was evaluated. X-ray diffraction (XRD) revealed polycrystalline cubic FeS2 with improved crystallinity as the deposition temperature increased. The optical energy gaps of the films ranged from 2.41 eV to 1.6 eV, decreasing with higher temperatures. Scanning electron microscopy (FE-SEM) showed that grain size increased from 30 nm to 180 nm as the temperature rose. Hall effect measurements confirmed the n-type conductivity of the film, with mobility decreasing from 5 to 3.17 cm2 V-1 s-1 at higher temperatures. The heterojunctions exhibited rectifying behavior, with the best ideality factor of 1.7 observed at 60 °C. The photodetector fabricated at 60 °C showed superior performance, with a responsivity of 0.37 A W-1 at 520 nm and 0.7 A W-1 at 770 nm, an external quantum efficiency of 52%, and a detectivity of 8 × 1011 Jones at 520 nm, making it the optimal configuration for efficient broadband photodetection.

Transmission electron microscopic study on rutile-type GeO2 film on TiO2 (001) substrate

Rutile-type GeO2 (r-GeO2) with an ultrawide bandgap of ∼4.7 eV has emerged as a promising material for next-generation power-electronic and optoelectronic devices. We performed transmission electron microscopy (TEM) observation to analyze the structural properties of r-GeO2 film on r-TiO2 (001) substrate at an atomic level. The r-GeO2 film exhibits a threading dislocation density of 3.6 × 109 cm−2 and there exist edge-, screw-, and mixed-type dislocations in the film as demonstrated by two-beam TEM. The edge-type dislocations have Burgers vectors of [100] and/or [110]. The bandgap of the r-GeO2 film is 4.74 ± 0.01 eV as determined by electron energy loss spectroscopy.

Impact of Cr doping on Hall resistivity and magnetic anisotropy in SrRuO3 thin films.

Hall effects, including anomalous and topological types, in correlated ferromagnetic oxides provide an intriguing framework to investigate emergent phenomena arising from the interaction between spin-orbit coupling and magnetic fields. SrRuO3 is a widely studied itinerant ferromagnetic system with intriguing electronic and magnetic characteristics. The electronic transport of SrRuO3 is highly susceptible to the defects (O/Ru vacancy, chemical doping, ion implantation), and interfacial strain. In this regard, we investigate the impact of Cr doping on the magnetic anisotropy and the Hall effect in SrRuO3 thin films. The work encompasses a comprehensive analysis of the structural, spectroscopic, magnetic, and magnetotransport properties of Cr-doped SrRuO3 films grown on SrTiO3(001) substrates. Cross-sectional transmission electron microscopy reveals a sharp and coherent interface between the layers. Notably, perpendicular magnetic anisotropy is preserved in doped films with thicknesses up to 113 nm. The resistivity exhibits a T^2 dependence below the Curie temperature, reflecting the influence of disorder and correlation-induced localization effects. Interestingly, in contrast to the undoped parent compound SrRuO3, an anomaly in the Hall signal has been observed up to a large thickness (56 nm) attributed to the random Cr doping and Ru vacancy. Based on our measurements, a field-temperature (H -T) phase diagram of anomalous Hall resistivity is constructed.

Exploring the Relationship Between Electrical Characteristics and Changes in Chemical Composition and Structure of OSG Low-K Films Under Thermal Annealing

The influence of annealing temperature on the chemical, structural, and electrophysical properties of porous OSG low-k films containing terminal methyl groups was investigated. The films were deposited via spin coating, followed by drying at 200 °C and annealing at temperatures ranging from 350 °C to 900 °C. In the temperature range of 350–450 °C, thermal degradation of surfactants occurs along with the formation of a silicon-oxygen framework, which is accompanied by an increase in pore radius from 1.2 nm to 1.5 nm. At 600–700 °C, complete destruction of methyl groups occurs, leading to the development of micropores. FTIR spectroscopy reveals that after annealing at 700 °C, the concentration of silanol groups and water reaches its maximum. By 900 °C, open porosity is no longer observed, and the film resembles dense SiO2. JV measurements show that the film annealed at 450 °C exhibits minimal leakage currents, approximately 5 × 10−11 A/cm2 at 700 kV/cm. This can be attributed to the near-complete removal of surfactant residues and non-condensed silanols, along with non-critical thermal degradation of methyl groups. Leakage current models obtained at various annealing temperatures suggest that the predominant charge carrier transfer mechanism is Poole–Frenkel emission.

Fabrication and Enhanced Flexibility of Starch-Based Cross-Linked Films.

The development of sustainable materials has driven significant interest in starch as a renewable and biodegradable polymer. However, the inherent brittleness, hydrophilicity, and lack of thermoplasticity of native starch limit its application in material science. This study addresses the limitations of native starch by converting it to dialdehyde starch (DAS) and cross-linking with polyether diamines via imine bonds. The effects of Jeffamine molecular weights (D-2000, D-400, and D-230) and mole ratios on the mechanical, thermal, and structural properties of starch-based films were examined. The cross-linked DAS/Js films exhibited significant enhancements in flexibility and toughness. Specifically, DAS/J2000 at a 0.03 mol ratio achieved a tensile strength of 62.9 MPa. In comparison, DAS/J400 at a 0.5 mol ratio demonstrated 126.2% elongation at break, indicating the balance between cross-linking density and chain mobility. X-ray diffraction (XRD) analysis revealed reduced crystallinity and tighter molecular packing with increased cross-linking. Dynamic mechanical analysis (DMA) indicated a decrease in Tg with an increasing mole ratio, reflecting enhanced molecular mobility. The results underscore the potential of optimized cross-linking conditions to produce starch-based films with properties that contribute to developing sustainable biopolymer materials.

Low thickness effect on the properties of Mn-doped ZnO thin films synthesized by sol-gel spin coating technique

In this study, 7% manganese-doped zinc oxide (MZO) thin films with varying low thicknesses were synthesized using the spin coating method. The structural, optical, and morphological properties of MZO films with different film thickness, were systematically investigated. The crystallite structure, superficial morphology, and optical characteristics were analyzed using X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), and ultraviolet–visible spectroscopy (UV-Vis). Structural analysis confirmed that all films exhibit a hexagonal wurtzite phase with a pronounced peak along the c-axis, and slight variation in low thickness significantly affected the structural parameters. The surface morphology demonstrated good uniformity, characterized by rounded grain shapes in the plane, while surface roughness was found to be increased with increasing film thickness. Optical analysis revealed that as the number of coatings increased, both transmittance and band gap energy decreased, accompanied by a redshift in the absorption edge across all samples. This behavior is attributed to light scattering, as well as an increase in the refractive index and dielectric function with visible light energy, influenced by the number of layers and corresponding crystallite size.

First Principles Study of Bismuth Vacancy Formation in (111)-Strained BiFeO3

Epitaxial strain is known to significantly influence the structural and functional properties of oxide thin films. However, its impact on point defect concentration has been less explored. Due to the challenges in experimentally measuring thin-film stoichiometry, computational studies become crucial. In this work, we use first-principles calculations based on density functional theory to investigate the formation and stability of Bi vacancies and Bi-O vacancy pairs in BiFeO3 (BFO) under (111) epitaxial strain. Our results demonstrate that compressive strain (−4%) decreases the formation enthalpy of Bi vacancies by 0.88 eV, whereas tensile strain (4%) increases it by 0.39 eV. Out-of-plane (OP) Bi-O vacancy pairs exhibit enhanced stability under both compressive and tensile strain, with formation enthalpy reductions of 1.49 eV and 1.05 eV, respectively. In contrast, in-plane (IP) vacancy pairs are stabilized under compressive strain but are insensitive to tensile strain. Finally, we discuss how these findings influence Bi stoichiometry during thin-film growth and the role of local strain fields in the formation of conducting domain walls.

Orientation-dependent structural properties during growth and growth mechanism of CoO films

The orientation-dependent local structural properties of CoO films on sapphire substrates during growth were investigated through linearly-polarized extended X-ray absorption fine structure (EXAFS) measurements. Specifically, CoO(111) and (100) crystals with a rock-salt structure (Fm3m) were epitaxially grown on α-Al2O3(0001) and (101¯2) substrates, respectively, at 700℃ using a radio-frequency sputtering system. The local structural properties of CoO films in the in-plane and out-of-plane orientations were quantitatively determined using linearly-polarized EXAFS at the Co K-edge during growth. The EXAFS analysis revealed that during the initial stages of growth, the local structural properties exhibit significant differences compared to thick films, with short atomic distances and large (small) Debye-Waller factors observed in the out-of-plane (in-plane) orientations. The local structural strain mostly diminished when approximately 20 CoO layers accumulated on the substrate. Density functional theory (DFT) calculations further supported these findings by confirming that cobalt atoms initially form stable bonds with the sapphire surface, leading to the simultaneous growth of oxygen and cobalt layers in a coordinated manner through layer-by-layer growth.

Effect of molarity on the optical and structural properties of CdS thin films deposited by spray pyrolysis on flexible plastic substrates

Effect of molarity on the optical and structural properties of CdS thin films deposited by spray pyrolysis on flexible plastic substrates

Tuning the optical, electrical, and structural properties of Cu-DLC thin films via simultaneous DC-RF unbalanced magnetron sputtering

This study evaluates the deposition of diamond-like carbon (DLC) films with copper impurities on a glass substrate using simultaneous direct current (DC) and radio frequency (RF) magnetron sputtering. The structural, optical, electrical, and mechanical properties, as well as the surface topography of the films, were investigated under various DC power levels using Raman spectroscopy, ellipsometry, UV-VIS, I-V measurements, nanoindentation, AFM, and FESEM. Results indicate that increasing the DC power to the graphite target from 60 to 120 W, while maintaining a constant 10 W of RF power to the copper target, enhances the optical absorption coefficient of the films and increases the optical bandgap from 0.95 eV to 1.55 eV. Concurrently, the refractive index decreases from 1.84 to 1.64. Raman spectra reveal that the G peak position and the ID/IG ratio decrease, suggesting an increase in sp³ bonds relative to sp2 bonds in the film structure. The surface topography shows increased deposition power raises the surface roughness of the films. Optical emission spectroscopy (OES) during deposition indicates that higher DC power reduces the relative intensity of Cu active species, leading to less Cu embedded in the film structure. Additionally, the emission spectrum shows an increase in hydrogen-containing species, suggesting a rise in sp³ C-H bonds compared to sp³ C-C bonds in the film structure.

Structural and optical properties of Eu-doped ZnO epitaxial thin films grown by pulsed-laser deposition

Pulsed-laser deposition was utilized to fabricate Eu-doped ZnO epitaxial films on c-plane sapphire substrates with Eu concentrations ranging from 0.5 to 4.0 at. %. The structural properties were analyzed using x-ray diffraction surface normal radial scans and azimuthal cone scans, which confirmed the epitaxy of the film samples. Reciprocal space mapping was performed on ZnO(101̄1) to visualize the effect of Eu incorporation. X-ray fluorescence mapping confirmed the homogeneous distribution of Zn and Eu, and x-ray absorption near-edge structure spectra directly confirmed the trivalent state of Eu ions. The optical properties were assessed using temperature-dependent photoluminescence (PL). Various defects were identified. With increasing Eu dopant concentration, PL emissions from defects and the Eu 4f-intraband transitions gradually became the predominant features in the PL spectra at low temperatures. Furthermore, PL analysis suggested that Eu ions substituted Zn, occupying sites with lower C3v symmetry due to the distortion caused by Eu incorporation.

Effect of thermal annealing on the luminescent and structural properties of the SiOxCy thin films by organic catalytic chemical vapor deposition

Photoluminescent silicon oxycarbide (SiOxCy) thin films were deposited on n-type (100) silicon substrates using the organic catalytic chemical vapor deposition (O-Cat-CVD) technique employing tetra-ethyl orthosilicate (TEOS) as an organic-based precursor. These films were annealed at a temperature of 500, 800 and 1000°C for 30 minutes in a nitrogen (N2) environment. The as-deposited and annealed SiOxCy films were analyzed using optical and structural characterizations, such as photoluminescence (PL), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), Secondary ion mass spectrometry (SIMS) and scanning electron microscopy (SEM). The PL spectrum of the as-deposited film showed emission in the blue-green region, while the annealed SiOxCy films showed strong emission from blue to near-infrared. The PL in all the films was attributed to different structural defects related to oxygen and carbon that act as radiative centers in the SiOxCy network. The annealed films showed an increase in the emission intensity, where the annealed film at 800°C displayed the highest emission intensity. This is related to an increase in the amount of radiative defects in the films due to structural and compositional changes after the thermal annealing (TA). XPS and SIMS measurements showed an oxygen incorporation with the TA, increasing from 54.59 at. % to 63.5 at. % for the as-deposited and annealed at 1000°C films, respectively. FTIR spectra showed an increase in the Si-O-C and Si-O-Si bonds and the hydrogen and other radicals desorption. These results support the creation of radiative centers due to structural changes in the films after the thermal annealing.

The Annealing Temperature Effect Enhances the Structural and Optical Parameters of Bi2Te3 Thermally Evaporated Thin Films

The current work investigates the influence of the annealing temperature (373, 473 K) on the structural and optical properties of Bi2Te3 thin films produced by the thermal evaporation technique. The crystal structure of samples is examined using an X-ray diffraction, indicating that Bi2Te3 thin films have a Rhombohedral structure with space group R-3m. The crystallite size (D) increased from 10.85 to 14.46 nm by increasing the annealing temperature. Additionally, increasing the annealing temperature reduces the micro-strain and the dislocation density from (3.33 × 10−3 to 2.5 × 10−3) and (8.49 × 1015 to 4.78 × 1015) Lines / m 2 , respectively. These micro-strain and dislocation density reductions refer to the crystallinity enhancement of sample Bi2Te3 thin films. The transmittance and reflectance spectra were measured using an Fourier transform infrared spectrometer. All samples reveal direct and indirect transition types and both direct and indirect optical energy gap decreased with increased annealing temperature from (0.325 to 0.29 eV) and (0.24 to 0.274 eV), respectively. From transmittance and reflectance data, the refractive index is calculated. These results reveal the refractive index decreasing as temperature annealing increased from (2.45–1.79) at 3250 nm. Other optical parameters such as absorption index, dielectric constant, energy loss function, and optical conductivity were estimated.

Low-temperature growth of CuS thin film on flexible substrates for photodetection

Abstract The covellite phase of copper sulfide thin film (CuS), due to its excellent electronic, optical and chemical properties, has attracted enormous attention in cutting-edge research. This is a comprehensive study of the structural, optical, morphological and electrical properties of CuS thin films deposited by chemical bath deposition technique on flexible polyethylene terephthalate (PET) substrates at different deposition temperatures, i.e. 25 °C, 40 °C, 55 °C and 70 °C for the fabrication of flexible photodetectors. X-ray diffraction and Raman spectral studies reveal the presence of hexagonal covellite phase (CuS), whereas the root mean square (RMS) roughness of CuS thin film increases with an increase in deposition temperature. The optical bandgap of CuS thin film is found to be decreased with an increase in deposition temperature. The optimized CuS thin film, deposited at 70 °C, exhibits a homogeneous surface with RMS roughness of 13.72 nm, mobility of 25.09 cm2 V−1s−1 and bandgap of 1.86 eV. The mobility of CuS thin film is found to be increased with the increase in deposition temperature. The flexible CuS photodetector, fabricated at 70 °C, exhibits better photoresponse characteristics, with the highest responsivity of 0.18 mA W−1, specific detectivity of 1.39 × 108 Jones and sensitivity of 173.25 % upon light illumination. The established photocurrent possesses an outstanding dependence on various intensities of illuminated light. Furthermore, the bending test of flexible CuS photodetectors reveals the absence of any sign of deterioration up to bending angle of 30°. This suggests that the Al/CuS-PET/Al photodetector device could be used in various wearable optoelectronic device applications.

Impact of bath temperature on the optical, structural, and photoelectrochemical properties of thin films of copper (II) oxide synthesized via electrodeposition method

Impact of bath temperature on the optical, structural, and photoelectrochemical properties of thin films of copper (II) oxide synthesized via electrodeposition method

Enhancing Low-Temperature Sensor Applications: Synergistic Effects of Ni Doping and SnO2 Interlayer on Spin-Coated ZnO Thin Films on Glass Substrate

This study investigates the effects of Nickel doping and a SnO2 interlayer on the structural, morphological, optical, and electrical properties of ZnO thin films. Undoped and Ni-doped ZnO films were fabricated on glass substrates, with and without an SnO2 interlayer, using the sol-gel spin coating method. The samples—denoted as ZG (undoped ZnO), NZG (Ni-doped ZnO), ZSG (undoped ZnO with SnO2 interlayer), and NZSG (Ni-doped ZnO with SnO2 interlayer)—underwent comprehensive characterization via XRD, AFM, PL, UV-Vis spectroscopy, Hall effect measurements, Hot probe, and Two-point method. XRD analysis confirmed successful Ni incorporation and enhanced ZnO crystallinity, particularly in the presence of the SnO2 interlayer. AFM analysis revealed improved grain distribution and size due to the synergistic effects of Ni doping and the SnO2 interlayer. UV-Vis results indicated significant impacts on transparency and the Urbach energy, with Ni doping alone broadening the bandgap. PL measurements showed that the synergistic effects quenched UV luminescence associated with the glass substrate, enhancing visible luminescence. Chromaticity analysis suggested that ZSG and NZSG samples are suitable for warm blue region applications. Electrical measurements revealed n-type conductivity across all films except NZG, with Ni doping increasing resistivity. Additionally, the ZSG (PTC) sensor exhibited a slightly higher sensitivity (0.3852 Ω/°C) compared to the NZSG sensor (0.3782 Ω/°C), with a similar trend observed in NTC sensors. These findings suggest that Ni-doped ZnO films with SnO2 interlayers could potentially serve as thermistors and RTDs, offering promising applications in temperature sensing and optoelectronics.

Influence of substrate temperature and Mn/Y co-doping concentration on the morphological, structural and optical properties of CuO nanostructured film deposited by the spray pyrolysis method

In this work, the effect of substrate temperature (ST) during deposition and dopant amount of Mn (1,3,5, and 7 %) and Y(3 %), (Mn/Y), on the physical properties of copper oxide (CuO) the nanostructured film were analyzed using different diagnostic tools. The pure and (Mn, Y) co-doped CuO thin films were deposited by the spray pyrolysis method, which is effective and easy to apply for any substrate. Deposited pure and (Mn,Y) co-doped CuO nanostructured films were investigated by X-ray diffraction (XRD), UV–Vis spectroscopy, and Field emission scanning electron microscopy (FESEM) techniques to analyze the influence of ST and co-doping on the structural, morphological, and optical properties of prepared films. The FESEM is used to visualize nanostructures on the surface of the film. Also, it is observed that the surface morphology of CuO film changes from a spherical-like to a nanocloumnar-like structure with increasing substrate temperature. The XRD diffractograms confirm the monoclinic crystal structure of CuO, in polycrystalline nature for all deposited films. UV–Vis spectra suggest changing the optical absorbance and the band gap of the pure and Mn/Y co-doped CuO nanostructured films. In the first investigation of this study, the better substrate temperature was obtained as 400 °C according to results. In the second part, the effect of Y and Mn doping with different content was analyzed for the CuO film deposited at the chosen ST of 400 °C. There is no observable crystalline structure variation in the XRD pattern, but the size of nanostructure and dislocation density are varied with Mn/Y co-doping. FESEM micrographs confirm the impact of the co-doping concentration on the size, shape, and surface properties of CuO nanostructured film. In addition, the optical band gap increases with Mn doping up to 3 % of Mn content and it was determined as 2.69 eV for the sample 3Mn/Y@CuO nanostructured film. The obtained results suggest that the substrate temperature has an important impact on the physical properties of the spray deposited CuO nanostructured film, and the structural, optical, and surface properties of the CuO nanostructured films may be engineered by Mn/Y doping concentration.

Enhanced optoelectronic properties of spray deposited antimony-doped tin oxide thin films

Antimony-doped tin oxide (Sb:SnO2) thin films with varying Sb concentrations were deposited using the spray pyrolysis technique. A comprehensive analysis of the films' elemental, structural, and optoelectronic properties is presented. All films possess a polycrystalline single-phase nature and have a tetragonal rutile structure. As Sb concentration increases, the unit cell shrinks continuously, suggesting proper substitution of Sn4+ by Sb5+. This substitution causes a continuous increase in the concentration of charge carriers and a reduction in electron mobility. X-ray photoelectron spectroscopy investigations revealed the presence of asymmetric Sn 3d core-level peaks distinguished by peak splitting, which increases with increasing carrier concentration. Utilizing the plasmon absorption model, an effective mass value of (0.51 ± 0.07)me for the conduction electron at the fermi level is obtained. With increasing Sb concentration, the optical energy gap increases gradually from 3.84 eV for undoped SnO2 to 4.35 eV for 5.0 at. % Sb. After considering the Urbach tailing phenomenon as well as the Moss–Burstein effect, this increase was attributed to the increase in Moss–Burstein energy due to increased charge carrier concentration. Our study revealed that the film doped with 2.0 at. % Sb has the best optoelectronic properties, with a figure of merit of 4.18 (Ω/cm2)−1.