Nanostructured Thin Films Research Articles

Grazing-incidence small-angle neutron scattering at high pressure (HP-GISANS): a soft matter feasibility study on grafted brush films

Grazing-incidence small-angle neutron scattering (GISANS) under pressure (HP-GISANS) at the solid (Si)–liquid (D2O) interface is demonstrated for the pressure-induced lateral morphological characterization of the nanostructure in thin (<100 nm) soft matter films. We demonstrate feasibility by investigating a hydrophobic {poly[(2,2,3,3,4,4,5,5-octafluoro)pentyl methacrylate]} (POFPMA)–hydrophilic {poly[2-(dimethylamino)ethyl methacrylate]} (PDMAEMA) brush mixture of strong incompatibility between the homopolymers, anchored on Si, at T = 45°C for two pressures, P = 1 bar and P = 800 bar. Our GISANS results reveal nanostructural rearrangements with increasing P, underlining P-induced effects in tethered polymer brush layers swollen with bulk solvent.

Effect of substrate temperature on the physical and sensing properties of nanostructured Fe2O3 thin films

Using Chemical Bath Deposition (CBD) Method and various substrate temperatures, Fe2O3 films were successfully deposited. The produced film thickness was around (320 nm). Using X-ray diffraction, researchers may examine the polycrystalline structure of Fe2O3 thin films. These nanofilms contain strong peaks at 2θ =32.21, suggesting a preferred orientation along the (110) plane, and the grain size increases with substrate temperature, according to XRD tests. When the base temperature was raised from 350 to 450 o C, the strain parameter decreased from 31.35 to 28.43. AFM testing of the surface morphology of the deposition of material yields excellent homogenous coatings. The findings show that the average particle size of the nanoparticles ranges from (69.8 to 32.7) nm. SEM images show Fe2O3 films at (350, 400, 450) °C. Increased temperature reduces grain size, influencing morphology variations. The absorbance increases with substrate temperatures and decreases rapidly at short wavelengths, which correspond to the energy gap. The transmittance increases with increasing wavelength range. It decreases with rising substrate temperatures. The band gap values vary from 2.17 eV to 2.06 eV by increasing the substrate temperatures from 350 to 450 o C. It was discovered that the band gap reduces as the temperature of the Fe2O3 substrate increases. In addition, the optical constants for all films, including the absorption coefficient, the refractive index, and the extinction coefficient, were computed. Fe2O3 film's resistance over time at 350, 400, and 450°C for 300 ppm NO2 demonstrates oxidation effect and temperature sensitivity. Sensitivity decreases with higher base temperature due to charge carrier recombination, affecting NO2 response.

Micro structures, Morphology and Optical Properties of Sb2O3: WO3, In2O3 Nanostructure Composite Thin Films

This work is concerned with the synthesis of two types of composites thin films (Sb2O3:WO3 and (Sb2O3:In2O3) with different concentrations (0.0,0.05,0.1, and 0.15). The prepared thin films are characterized with the use of the X-ray diffraction atomic force microscope AFM and UV-Vis–infrared spectrophotometer. The structural examination shows that both composite's thin films were polycrystalline with nano size with cubic phase as majority and orthorhombic phase as minority phase. The crystal size decreases from 34.6 to 24.7 and 21.7 nm for (Sb2O3:WO3) and (Sb2O3:In2O3) thin films, respectively. The average roughness shows non-regular growth by increasing the concentration of both oxides. The optical energy band gap shows a red shift for both types of nanostructure thin films, which populate these composited thin films for solar cell applications.

Preparation and Characterization of Nanostructured ITO Thin Films by Spray Pyrolysis Technique: Dependence on Annealing Temperature

Transparent conducting oxides (TCOs) like Indium tin oxide (ITO) have wide attention from all scientists which have low resistance and high visible light transmittance, used as transparent electrodes in many optoelectronic devices such as liquid crystal displays, touch screens, light emitting diodes, and solar cells. In this research, the relationship between the crystallization, optical transmittance, and surface roughness of nanostructured ITO thin films and the change in annealing temperature was investigated. To enhance the efficiency of this material in optoelectronic applications, both the optical transmittance in the visible region and the crystallite size must be increased. These results can be obtained by the heat treatment of the films. Nanostructured ITO thin layer films have been successfully prepared at a substrate temperature equal to (350)℃ by chemical spray pyrolysis (CSP) technique. The physical characterizations of nanostructured ITO thin layer films were investigated at different annealing temperatures (400,450 and 500)℃. The presence of diffraction peaks indicates that the as-deposited and post annealed films are polycrystalline cubic structure and the peak (400) is a preferred growth orientation. For all samples the value of intensity of diffraction peaks increases with increasing substrate temperature. The crystallite size of nanostructured ITO thin films is strongly related to the annealing temperature. The crystallite size estimated from XRD was found to rise with rising annealing temperature. The surface roughness of nanostructured ITO thin layer films increases with rising annealing temperature. High values of transmittance have been measured in the visible region 550 nm equal to (70, 82, 84 and 88)% corresponding to annealing temperature (350,400,450 and 500)℃ respectively.

Hierarchical exsolution in vertically aligned heterostructures

Metal nanoparticle exsolution from metal oxide hosts has recently garnered great attention to improve the performance of energy conversion and storage devices. In this study, the nickel exsolution mechanisms in a vertically aligned nanostructure (VAN) thin film of heteroepitaxial (Sr0.9Pr0.1)0.9Ti0.9Ni0.1O3−δ-Ce0.9Gd0.1O1.95 with a columnar architecture was investigated for the first time. Experimental results and Density Functional Theory (DFT) calculations reveal that the multiple vertical interphases in a VAN with a hierarchical arrangement provide faster and more selective Ni diffusion pathways to the surface than traditional bulk diffusion in epitaxial films. Kinetic studies conducted at different temperatures and times indicate that the nucleation process of the exsolved metal nanoparticles primarily takes place at the surface through the phase boundaries of the columns. The vertical strain is crucial in preserving the film’s microstructure, yielding a robust heteroepitaxial architecture after reduction. This innovative heteromaterial opens up new possibilities for designing efficient devices through advanced structural engineering to achieve controlled nanoparticle formation.

Acetone Sensors Based on Al-Coated and Ni-Doped Copper Oxide Nanocrystalline Thin Films.

Acetone detection is of significant importance in various industries, from cosmetics to pharmaceuticals, bioengineering, and paints. Sensor manufacturing involves the use of different semiconductor materials as well as different metals for doping and functionalization, allowing them to achieve advanced or unique properties in different sensor applications. In the healthcare field, these sensors play a crucial role in the non-invasive diagnosis of various diseases, offering a potential way to monitor metabolic conditions by analyzing respiration. This article presents the synthesis method, using chemical solutions and rapid thermal annealing technology, to obtain Al-functionalized and Ni-doped copper oxide (Al/CuO:Ni) nanostructured thin films for biosensors. The nanocrystalline thin films are subjected to a thorough characterization, with examination of the morphological properties by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) analysis. The results reveal notable changes in the surface morphology and structure following different treatments, providing insight into the mechanism of function and selectivity of these nanostructures for gases and volatile compounds. The study highlights the high selectivity of developed Al/CuO:Ni nanostructures towards acetone vapors at different concentrations from 1 ppm to 1000 ppm. Gas sensitivity is evaluated over a range of operating temperatures, indicating optimum performance at 300 °C and 350 °C with the maximum sensor signal (S) response obtained being 45% and 50%, respectively, to 50 ppm gas concentration. This work shows the high potential of developed technology for obtaining Al/CuO:Ni nanostructured thin films as next-generation materials for improving the sensitivity and selectivity of acetone sensors for practical applications as breath detectors in biomedical diagnostics, in particular for diabetes monitoring. It also emphasizes the importance of these sensors in ensuring industrial safety by preventing adverse health and environmental effects of exposure to acetone.

Measurements of fluctuation-induced in-plane magneto-conductivity of granular aluminum film

The phenomenon of Berezinskii–Kosterlitz–Thouless (BKT) phase fluctuations and the superconducting fluctuations is investigated in a 40 nm thick granular aluminum film using magneto-transport measurements. The transport measurements suggest the possibility of strong electron–phonon (el–ph) interactions in contrast to a Bardeen–Cooper–Schrieffer superconductor. It shows a BKT transition of 2.304 K and a superconducting mean-field transition at 2.32 K. The presence of the resistive tail even before the BKT transition reflects the abundance of thermally activated free vortices. By analyzing the excess conductivity, Gaussian–Ginzburg–Landau superconducting fluctuations are observed above the superconducting transition, which causes rounding of the transition region even before the superconducting transition. The temperature dependence of the fluctuation conductivity in zero magnetic field exhibits distinct signatures of the two-dimensional direct Aslamazov–Larkin theory, with a significant contribution from the Maki–Thompson (MT) model. Furthermore, the anomalous behavior of the fluctuation conductivity at higher temperatures and perpendicular magnetic fields (up to 700 mT) is explained in terms of the total-energy cutoff (=0.72) in the low-wavelength region of the superconducting fluctuations and a pair-breaking parameter (∼0.031). Further studies on the pair-breaking parameter indicate the presence of the el–ph scattering, which diminishes the MT contribution. Our study carries important bearings on how the BKT phase fluctuations and superconducting amplitude fluctuations control the conductivity of granular superconductor near and above the transition region as non-equilibrium properties of weakly disordered granular superconductors. This research is of significance, offering insights into the fundamental properties of granular superconductivity and aiding in the comprehension of nano-structured thin film devices.

Electrosynthesis and characterization of nanostructured manganese dioxide thin film on stainless steel electrode for electrochemical degradation of phenol

Electrosynthesis and characterization of nanostructured manganese dioxide thin film on stainless steel electrode for electrochemical degradation of phenol

Synthesis and sensing characterizations of nanostructured tin-doped Fe2O3 thin films

Synthesis and sensing characterizations of nanostructured tin-doped Fe2O3 thin films

Boosting photoelectrochemical water splitting performance via nanostructured Ag-CuO thin films

Undoped and doped copper oxide (CuO) with silver (Ag) was prepared using the SILAR technique on the ITO substrate to generate green hydrogen from the water-splitting process. The (−111) and (111) were the most intense reflections of crystallographic planes observed in pure and Ag-doped CuO thin films. Ag doping within the crystal structure of pristine leads to increasing the crystallite size. FESEM images show homogeneity and uniform distribution for the pure and Ag-doped CuO thin films that confirm the particles have small sizes, give more features and are responsible for the target application. The doping process affected the energy band gap where it was 2.2 eV for the pure sample then descended to 1.9 eV as doping reached 5 % concentration of Ag element. The photoelectrochemical testing showed that the Ag 5 % content photoelectrode has a high value of photocurrent density approximately ∼ - 5 mA/cm2.

Effects of cadmium doping on the physical and sensing properties of nanostructured CuO thin films

This investigation used sol-gel deposition to create undoped CuO and CuO: Cd thin films. All films of undoped CuO and CuO: Cd phase exhibit four dominating peaks at 35.52°, 38.84°, 53.37°, and 68.23°, which are correspondingly assigned to the (022), (200), (020), and (220) planes, according to X-ray diffraction analysis. The dislocation density reduced from 60.55 to 49.94, the strain decreased from 26.98 to 24.60, and the grain size of the produced films measured by XRD was 12.85–14.15 nm. Atomic force microscopy (AFM) was used to study the morphology. SEM analysis showed increased aggregation with higher Cd content, resulting in a more uniform porous structure. The optical band gap decreases for all samples as the cadmium content increases, ranging from 2.28 to 2.14 eV. Similarly, the refractive index and extinction coefficient values decrease as the cadmium content increases for all samples. The gas sensor detects H2 (375 ppm) using CuO film cadmium doping, which enhances sensitivity, CuO: 4% exhibits highest resistance. Sensitivity decreases with higher doping, indicating reduced sensor responsiveness.

Management of Light Absorption Based on Sidewall Reflection for Fabricating High-Performance Flexible Nano-Coned Sb2Se3 Thin Film Photovoltaics.

High performance and robustness are the key factors to boosting wearable and portable applications. Although the 1D crystal structure makes the Sb2Se3 thin film more tolerant to physical deformation upon bending, the conventional planar structures still cannot undergo repeated mechanical bending due to the induced stress/strain inside devices, which can be well addressed by constructing three-dimensional nanostructures. Besides, the electron diffusion length has two values, 0.3 μm in the [221] direction and 1.7 μm in the [001] direction, in the Sb2Se3 thin film, which limits the absorber thickness, for getting an effective carrier collection; thus, a strong light trapping effect enabling sufficient light harvesting is needed to allow the use of a very thin light absorption layer. Herein, the nanoconed Sb2Se3 solar cells have been designed, and their light absorption behaviors were investigated within a finite-element simulation under the substrate back-reflection, indicating that the reflection of the bottom part always works positively, while the effect of the nanocone sidewall on absorption enhancement largely depends on its geometry, arising from resonant or scattering modes. These results provide a practical guide in designing/establishing an easier/simpler way to fabricate high-performance and mechanically stable flexible nanostructured Sb2Se3 thin film solar cells.

Effect of electrodeposition of AuPt nanostructure thin films on the electrocatalytic activity of counter electrodes: DSSCs application

Effect of electrodeposition of AuPt nanostructure thin films on the electrocatalytic activity of counter electrodes: DSSCs application

Femtosecond Laser Ablation and Delamination of Functional Magnetic Multilayers at the Nanoscale.

Laser nanostructuring of thin films with ultrashort laser pulses is widely used for nanofabrication across various fields. A crucial parameter for optimizing and understanding the processes underlying laser processing is the absorbed laser fluence, which is essential for all damage phenomena such as melting, ablation, spallation, and delamination. While threshold fluences have been extensively studied for single compound thin films, advancements in ultrafast acoustics, magneto-acoustics, and acousto-magneto-plasmonics necessitate understanding the laser nanofabrication processes for functional multilayer films. In this work, we investigated the thickness dependence of ablation and delamination thresholds in Ni/Au bilayers by varying the thickness of the Ni layer. The results were compared with experimental data on Ni thin films. Additionally, we performed femtosecond time-resolved pump-probe measurements of transient reflectivity in Ni to determine the heat penetration depth and evaluate the melting threshold. Delamination thresholds for Ni films were found to exceed the surface melting threshold suggesting the thermal mechanism in a liquid phase. Damage thresholds for Ni/Au bilayers were found to be significantly lower than those for Ni and fingerprint the non-thermal mechanism without Ni melting, which we attribute to the much weaker mechanical adhesion at the Au/glass interface. This finding suggests the potential of femtosecond laser delamination for nondestructive, energy-efficient nanostructuring, enabling the creation of high-quality acoustic resonators and other functional nanostructures for applications in nanosciences.

On analysis of structural and optical absorption characterization of Bi35Sb5Se60 nanostructured thin films for photosensing application

In this extensive study, the primary focus is directed towards the intricate exploration of the optical absorption characteristics inherent in nanostructured Bi35Sb5Se60 thin films, prepared by thermal evaporation under a vacuum of 10−5 Torr, ensuring high purity and uniformity for optoelectronic applications. With a particular emphasis on their prospective application in photosensing devices. The research employs a comprehensive approach, integrating various spectrophotometric measurements that encompass both transmission and reflection analyses. The meticulous examination of the absorption edge characteristics reveals a direct energy gap of 1.82 eV, providing a foundational understanding of the material's electronic structure. The determination of the dispersion energy at 6.35 eV and the oscillator energy at 2.96 eV further enriches the understanding of the material's optical behavior, shedding light on its capacity to interact with incident light. A noteworthy highlight emerges with the identification of high photosensitivity exhibited by the heterojunction, particularly under lower reverse bias conditions, underscoring its potential utility in photosensing applications. The PL spectra reveal a highly broadened defect emission band with peaks at 475 nm, 490 nm, and 540 nm, providing insights into the recombination processes within the material. The identification of emission peaks related to the conduction band edge and acceptor levels further enhances the comprehension of the material's optical and electronic characteristics. underscores the potential of these nanostructured thin films for efficient photosensing devices. The findings presented in this research not only advance the understanding of the material's properties but also lay a robust foundation for further research and development in the design and optimization of photoresponsive devices within the realm of optoelectronic technologies.

Flexible transparent conductors with a percolated Ag nanostructure and its application as efficient self-bias plasmonic photodetector

A percolated silver (Ag) nanostructured-based transparent conductor has been deposited by physical vapor deposition (PVD) technique where lateral growth of Ag has been enhanced by a pre-deposited Ag-TiO2 thin film. This Ag-TiO2 film has embedded Ag nanoparticles (NPs) within TiO2 thin film which is grown in a low temperature (100 °C) solution processed technique. This process includes Li4Ti5O12 (LTO) thin film deposition by a sol–gel method followed by ion-exchange (Li+ → Ag+) process to yield an Ag-TiO2 thin film. The percolated Ag network has appeared as soon film mass-thickness reaches close to 10 nm, resulting in an abrupt drop of electrical resistivity of the film. This percolated Ag nanostructured thin film (10 nm Ag/Ag-TiO2/plastic) has resistivity of ∼50 Ω/□ and an average visual transmittance of >70 % up to 450 nm. In higher wavelength range, transparency gradually reduces, and it reaches to ∼50 % at 600 nm which is mostly due to the plasmon absorption of this film. By utilizing its combined optical transparency and surface plasmon absorption, this film has been used to develop plasmonic hot electron photodetectors where Ag-thin film works as transparent electrode as well as plasmon induced photo-excited hot electron generation. Device has been fabricated on a heavily doped n type Si (n++-Si) with a metal–semiconductor-metal (M−S−M) device geometry. External quantum efficiency (EQE) data reveal that photocurrent of this device is mostly generated in the plasmonic absorption region with a peak detectivity of 2.84 × 1012 Jones at 510 nm under −3V external bias. Besides, the device shows fast response with a response time of ∼25 ms.

Insight into deposition duration-varied crystallinity, optical parameters, morphology and electrical properties of solution-processed nanostructured CdSSe thin films

Nanostructured cadmium sulpho selenide (CdSSe) films have been grown onto glass substrates for different deposition durations via a facile solution-based method known as chemical bath deposition (CBD). XRD studies revealed that the crystallites in the films possessed hexagonal (wurtzite) structures with predominant orientation along the (002) plane. The crystallite size increased from ∼5.95 nm to ∼16.69 nm with the increase in deposition duration from 1 h to 4 h. The absorbance, transmittance and reflectance measurements were carried out. A transparency of ∼(50–80) % was obtained for the films. The direct optical energy band gap was found to decrease from 1.982 eV to 1.952 eV with the increment of deposition duration from 1 h to 4 h. SEM micrographs of the films revealed the presence of nano spherical-shaped grains with an average size ranging from ∼305 nm to ∼612 nm. HRTEM images illustrated the presence of compact nano-spherical grains and nano-crystallites distributed in random orientations. Raman spectroscopy divulged the presence of CdSe and CdS vibrational Raman modes and overtones in the films. PL spectra revealed a prominent red emission band along with weak luminescent bands in the yellow-red emission region. The presence of Cd–Se and Cd–S bonds in the films was validated using FTIR analysis. Electrical investigation revealed the linear current‒voltage relationship for the films with the rise in conductivity with deposition duration. Hence, deposition duration stands out as a vital parameter for modulating the properties of CdSSe thin films for use in photovoltaic devices and optoelectronics.

The pH-dependent properties of cuprous oxide thin films prepared by electrochemical deposition for liquid petroleum gas sensing

Efficient liquid petroleum gas sensing was investigated by modulating the pH level (8, 9, 10, 11, and 12) of electrochemically deposited nanostructured cuprous oxide thin films in a lactate bath. The synthesized films were characterized by surface contact angle, XRD, SEM, UV–Vis absorption, Mott-Schottky, and AC impedance spectroscopy measurements. These displayed a unique initial increment or decrease followed by a persistent decrement or increment at pH 9–10. This turning pH point exhibited the least wetting polycrystalline Cu2O growth with the smallest crystallite size of ∼ 45 nm, the highest dislocation density of ∼50 µm−2, and a strain of 0.03 according to X-ray diffraction. SEM micrographs identified ∼ 1 µm-sized, closely structured grains with trigonal-prismatic shapes. The Mott-Schottky plots drawn from C-V measurements revealed a significant dependence of flat band potential and free carrier density on the deposition bath pH level. Cu2O films deposited using the lactate bath changed the conductivity at pH 9 from n-type to p-type when increasing the pH value. With the conductivity transition, films prepared at pH 9 displayed a relatively high direct band gap energy of 2.28 eV. Liquid petroleum gas (LPG) sensing at 70 °C demonstrated the most substantial gas response of 11.5 % at pH 10 Cu2O films. Cu2O thin films deposited at pH 9 emerged as the most stable and reproducible p-Cu2O LPG sensor, with response and recovery times ranging from 20 to 25 seconds. Remarkable changes in the film structures and morphologies were revealed with pH values above 9 after the gas exposure. The grain shape and distribution of pH 9 remained unchanged, assuring the stability of the sensing platform.

Molecules as Lubricants at the Nanoscale:Tunable Growth of Organic Structures from Nano- to Millimeter-Scale Using Solvent Vapour Annealing.

The creation of ordered structures of molecules assembled from solution onto a substrate is a fundamental technological necessity across various disciplines, spanning from crystallography to organic electronics. However, achieving macroscopic order poses significant challenges, since the process of deposition is inherently impacted by factors like solvent evaporation and dewetting flows, which hinder the formation of well-organized structures. Traditional methods like drop casting or spin coating encounter limitations due to the rapid kinetics of solvent evaporation, leading to limited control over final uniformity and order. In response to these challenges, Solvent Vapour Annealing (SVA) has emerged as a promising solution for realizing ordered molecular structures at scales ranging from nano- to milli- meters. SVA decouples the self-assembly stage from the deposition stage by utilizing solvent vapours which can enable rearrangement, movement, and diffusion of large molecules on the surface even on a macroscopic scale. Essentially acting as "molecular lubricants," solvent vapours enable the formation of well-ordered molecular films. This review discusses the advancements, obstacles, and promising strategies associated with utilizing SVA for the development of innovative nanostructured thin films, and emphasizes the originality and effectiveness of molecular assembly on substrates achieved through this approach.

Tailoring the optoelectronic and spintronics properties of Cr-doped ZnS nanostructure thin films

This paper discusses the tailoring of the optoelectronic and spintronic of Cr3+-doped ZnS nanostructured electron beam evaporated thin films. The XRD measurements confirm the zinc blende cubic structure for the films with a preferred orientation along the (111) direction. The nanostructured features of the films were verified from the XRD and AFM results. The EDXS and XPS data show the stoichiometric chemical and electronic states of the films. Spectrophotometry measurements for the films show that the energy gap decreases from 3.67 eV to 3.43 eV as the Cr3+ increases from 0 at. % to 8.0 at.%. Such reduction of the Eg of the Cr3+-doped ZnS is attributed to the sp-d coupling. The strong PL asymmetric peak of the Cr3+-doped ZnS is observed, which is quenched and red shifted with increasing Cr doping level. Furthermore, the magnetic measurements show the occurrence of weak room temperature ferromagnetic behavior. On the other hand, the results further show that the magnetization increases with the increase of the Cr3+ dopants up to x = 0.05, then decreases with increasing the Cr doping above x = 0.05. This can be attributed to the development of the antiferromagnetic ordering.