Pulsed Laser Deposition‐based Thin Film Microbatteries

Emerging applications for robust small format or distributed devices feature a need for power and rechargeable lithium‐ion batteries could play a significant role. This review focuses on a high precision technique to controllably grow thin‐film electrodes or full all‐solid‐state batteries, that is, pulsed laser deposition (PLD). The technique and solid‐state batteries are introduced followed by a detailed showcase of the depth of PLD‐based growth undertaken on cathodes, electrolytes, anodes and whole microbatteries. Emphasis is placed on the various characterization techniques available to study PLD grown components and devices, and how interfaces become both critical and arguably easier to probe in PLD grown films or devices. This work provides a perspective on the techniques, its opportunities for electrodes and devices, and how to probe the resulting growth and its evolution in batteries.     

Fluorous solvent‐soluble imaging materials containing anthracene moieties

Highly fluorinated photoresist polymers that can undergo photodimerization reactions were designed using an anthracene‐based monomer. Through the random radical copolymerizations of 6‐(anthracen‐9‐yl)hexyl methacrylate ( AHMA ) and semiperfluorodecyl methacrylate ( FDMA ) with four different compositions, polymers with M_n = 20,000–27,000 (M_w/M_n = 2.0–2.9) were prepared in benzotrifluoride. The polymers, in particular fluorous solvent‐soluble imaging material‐2 ( FSIM‐2 ), showed sufficient solubility in fluorous solvents, including hydrofluoroethers, but were rendered insoluble by UV exposure (365 nm). This photochemical solubility change was evaluated quantitatively by a quartz crystal microbalance technique, along with tracing the chemical reaction by UV–vis spectroscopy. Finally, FSIM‐2 and fluorous solvents were applied to the photolithographic patterning of organic light‐emitting diode pixels. In the patterning protocol involving the lift‐off of resist films in fluorous solvents, FSIM‐2 was recognized as a promising photoreactive material when compared with a reference polymer P(FDMA‐MAMA) , which necessitates acidolysis reactions for lithographic imaging. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1252–1259     

Annealing effect on the structural and magnetic properties of nickel ferrite thin films

Nickel ferrite is a soft magnetic material with inverse spinel structure. Soft ferrite films are used in microwave devices, integrated planar circuits, etc., because of their high resistivity. In this work, thin films of nickel ferrite were deposited on Si (100) substrate by using pulsed laser deposition (PLD) technique. The thickness of the film was measured by surface profilometer and also by X‐ray reflectivity (XRR). The films were annealed at three different temperatures to observe the effect on the structural and magnetic properties of the film. The films were characterised by X‐ray diffraction (XRD), Raman spectroscopy and vibrating sample magnetometer (VSM) to study the structural and magnetic properties. Copyright © 2010 John Wiley & Sons, Ltd.     

Influence of rapid thermal annealing on structure and interfacial characteristic of ZnO thin films

Highly C‐axis oriented ZnO thin film was manufactured by radio‐frequency magnetron sputtering technique on Si (111) substrate. The main objective was to study the influence of rapid thermal annealing (RTA) temperature on the structure and interfacial characteristic of ZnO thin films. X‐ray diffraction results showed that the ZnO thin films annealed at 600 °C by RTA technique had a perfect C‐axis preferred orientation compared to the other ZnO thin films, and the full width at half maximum of ZnO (002) rocking curve measurements indicted that the RTA‐annealed ZnO thin films possessed better crystal structure. Atom force microscopy displayed that the grain size of RTA‐annealed ZnO thin films was fine and uniform compared with the as‐deposited ZnO thin films, although the grains grew in RTA process and the root meant square roughness was smaller than that of as‐deposited films. High‐resolution transmission electron microscopy showed that there was an obvious amorphous layer between ZnO thin films and Si substrate, but the RTA‐annealed ZnO thin films exhibited larger and denser columnar structure and a preferred orientation with highly c axis perpendicular to the amorphous layer. Copyright © 2012 John Wiley & Sons, Ltd.     

Optimization of large area pulsed laser deposition of YBaCuO thin films by SNMS depth profiling and rutherford backscattering

The scaling up of established deposition techniques like pulsed laser deposition (PLD) to larger substrate diameter is a main condition for the technological application of high-T_c superconducting (HTSC) thin films. SNMS depth profiling and RBS have been used to control the homogeneity of film thickness and stoichiometry of Au/YBaCuO/CeO₂ thin film systems deposited on 3-inch sapphire wafers by PLD. A systematic dependence has been found for the relative SNMS sensitivity factors (RSF) on the structural state of YBaCuO. Therefore, a calculation of the composition of the epitaxial YBaCuO thin films is not possible using RSF determined from polycrystalline YBaCuO target material. The interdiffusion of thin films and substrate has been investigated in dependence on the deposition temperature by SNMS depth profiling. The obtained homogeneity of film thickness and stoichiometry over the entire 3-inch diameter proofs the suitability of PLD for in-situ deposition of 3-inch wafers by YBaCuO thin film systems for microwave applications.     

Dual purpose laser ablation-inductively coupled plasma mass spectrometry for pulsed laser deposition and diagnostics of thin film fabrication: Preliminary study

PLD (pulsed laser deposition) is an attractive technique to fabricate thin films with a stoichiometry reflecting that of the target material. Conventional PLD instruments are more or less black boxes in which PLD is performed virtually “blind”, i.e. without having great control on the important PLD parameters. In this preliminary study, for the first time, a 213 nm Nd-YAG commercial laser ablation-inductively coupled plasma mass spectrometer (LA-ICPMS) intended for microanalysis work was used for PLD under atmospheric pressure and in and ex situ ICPMS analysis for diagnostics of the thin film fabrication process.A PLD demonstration experiment in a He atmosphere was performed with a Sm_13.8Fe_82.2Ta_4.0 target-Ta-coated silicon wafer substrate (contraption with defined geometry in the laser ablation chamber) to transfer the permanent magnetic properties of the target to the film. Although this paper is not dealing with the magnetic properties of the film, elemental analysis was applied as a means of depicting the PLD process. It was shown that in situ ICPMS monitoring of the ablation plume as a function of the laser fluence, beam diameter and repetition rate may be used to ensure the absence of large particles (normally having a stoichiometry somewhat different from the target). Furthermore, ex situ microanalysis of the deposited particles on the substrate, using the LA-ICPMS as an elemental mapping tool, allowed for the investigation of PLD parameters critical in the fabrication of a thin film with appropriate density, homogeneity and stoichiometry.     

Quantitative Image Analysis of Fractal‐Like Thin Films of Organic Semiconductors

Morphology modulation offers significant control over organic electronic device performance. However, morphology quantification has been rarely carried out via image analysis. In this work, we designed a MATLAB program to evaluate two key parameters describing morphology of small molecule semiconductor thin films: fractal dimension and film coverage. We then use this program in a case study of meniscus‐guided coating of 2,7‐dioctyl[1]benzothieno[3,2‐b][1]benzothiophene (C₈‐BTBT) under various conditions to analyze a diverse and complex morphology set. The evolution of morphology in terms of fractal dimension and film coverage was studied as a function of coating speed. We discovered that combined fractal dimension and film coverage can quantitatively capture the key characteristics of C₈‐BTBT thin film morphology; change of these two parameters further inform morphology transition. Furthermore, fractal dimension could potentially shed light on thin film growth mechanisms. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1622–1634     

Dual capacitor technique for measurement of through‐plane modulus of thin polymer films

Polymer thin films are widely used as coatings and interlevel dielectrics in microelectronic applications. In thin‐film structures, stresses are generated due to interaction with adjacent layers and film shrinkage due to solvent evaporation or curing. This causes polymer chain orientation resulting in anisotropic (direction dependent) film properties. The dual capacitor technique has been developed to measure in situ, the through‐plane (z) stress‐strain behavior of thin polymer films. A parallel plate capacitor device and an interdigitated electrode structure were used as sensors to detect changes in dielectric permittivity and thickness of thin polymer films under compression. The analytical and finite element models used to interpret the capacitance measurements have been presented. The Clausius–Mossotti equation was used to determine the volume change in the film from the permittivity measurements. Results have been reported for 10–14 μm thick, Cyclotene 4026‐46 benzocyclobutene films and 10–12 μm thick films of polyimide PI‐2611. The Cyclotene 4026‐46 films were found to be mechanically isotropic, whereas the PI‐2611 films were highly anisotropic. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1634–1644, 2000     

Pulsed Laser Deposition as a Tool for the Development of All Solid-State Microbatteries

All-solid-state lithium ion batteries (LIB) are currently the most promising technology for next generation electrochemical energy storage. Many efforts have been devoted in the past years to improve performance and safety of these devices. Nevertheless, issues regarding chemical and mechanical stability of the different components still hinder substantial improvements. Pulsed laser deposition (PLD) has proved to be an outstanding technique for the deposition of thin films of materials of interest for the fabrication of LIB. Thanks to its versatility and possible fine tuning of the thin film properties, PLD promises to be a very powerful tool for the fabrication of model systems which would allow to study in detail material properties and mechanisms contributing to LIB degradation. Nevertheless, PLD presents difficulties in the deposition of LIB components, mainly due to the presence of elements with large difference of atomic mass in their chemical composition. In this review, we report the main challenges and solution strategies used for the deposition through PLD of complex oxides thin films for LIB.     

Multifractal analysis for Cu/Ti bilayer thin films

Two bilayer thin films with different stacking sequences, Cu/Ti/Si and Ti/Cu/Si, were deposited by DC magnetron sputtering technique. X‐ray diffraction technique was used to measure the crystallization structures, and scanning electron microscopy and atomic force microscopy were used to measured surface morphology. The multifractal spectra f(α)‐α was used to characterize the surface morphology. The result of |q|_max ≤ 53 is obtained by multifractal analysis. The shape of the multifractal spectra f(α) ? α is hook‐like for Cu/Ti/Si and bell jar‐like for Ti/Cu/Si. The spectrum width Δα = α_max ? α_min and Δf(=f(α_min) ? f(α_max)) of the multifractal spectra is able to quantitatively analyze the growth and surface roughness of the Cu/Ti bilayer thin films. The surface of Ti/Cu/Si thin film is more uniform and smoother than the film of Cu/Ti/Si. Copyright © 2013 John Wiley & Sons, Ltd.     

A novel technique for improving interferometric determination of emulsion film thickness by digital filtration

Determination of the thickness of emulsion films by using the film interferometric images is usually less accurate than that of foam films, due to the close values of the refractive indices of the liquid film and adjacent liquid phases (hence, low contrast and high level of noise at high magnification). A new technique was developed to improve the thickness determination by obtaining the interferometric images without directly filtering the illuminating light, as is usually done in the classical Scheludko interferometric technique. The new method then uses digital filtration during the off-line image post-processing to obtain monochromatic interferometric images required for the thickness determination. The technique was tested with foam films stabilised by sodium dodecyl sulfate and successfully applied to determine thickness of toluene-water-toluene emulsion films using the green and red digital filters. Results for emulsion film thickness determined by either the green or red digital filtration are comparable, thus validating the new technique developed here for emulsion films.     

A microfluidic electrochemical detection technique for assessing stability of thin films and emulsions

An experimental technique is developed for assessing stability of thin liquid films by application of electric potential to compress the liquid film and to simultaneously measure the electrical properties of the system. The concept involves creating a thin film at the intersection of two microchannels etched onto a glass substrate. A ramped DC potential difference is applied across the film, which develops an electrical stress across the film. Increasing the potential to a critical value leads to the rupture of the film. The critical potential is used to assess the stability of the liquid film. Small channel dimensions in this microfluidic platform allow characterization of thin films formed between micron-sized droplets representing systems with high capillary pressures, analysis of which are typically beyond the scope of conventional thin film characterization techniques. The results of DC potential breakdown of films show that critical potential can be considered as a measure of thin film stability.     

RF-plasma polymerization and characterization of polyaniline

Suitable modifications are done in a RF sputtering set up to facilitate synthesis of polyaniline thin film by RF-plasma polymerization process. The synthesized films are characterized by FTIR, XRD, Ellipsometry, UV-visible absorption & reflection and SEM. The films prepared are highly cross-linked, amorphous in nature and have band gap of 2.07 eV. SEM images show the uniformity in film morphology. The refractive index of the films is determined to be 1.11 and dielectric constant is 1.12 at a wavelength 620 nm in the visible region.     

Nanostructural properties of zinc oxide thin films grown on non‐planar substrates

The crystallographic structure of zinc oxide thin films grown on optical fibres using single source chemical vapour deposition (SSCVD) was analysed using near edge X‐ray absorption fine structure (NEXAFS). Zinc diethyl carbamate was used as a precursor for the growth of highly conformal films in a one‐step deposition process without substrate rotation and at substrate temperatures of 400–575 °C. It was found that the growth temperatures greatly affected the crystallographic structure of the film with no preferred crystallographic orientation and negligible crystallinity at low temperatures and very high crystallinity with pure c‐axis orientation at high temperatures. Cross‐sectional analysis of the films by scanning electron microscopy (SEM) showed the presence of a film at all points around the fibre. These films generally consisted of densely packed columns that bore a strong resemblance to c‐axis‐oriented films grown on planar substrates. Copyright © 2005 John Wiley & Sons, Ltd.     

Preparation and Magnetic Properties of Submicron CrO2 Thin Film on Poly-crystal TiO2 Film

The submicron chromium dioxide(CrO₂) thin film was fabricated on a poly-crystal titania(TiO₂) film using Si wafers as substrates by atmospheric pressure chemical vapor deposition(CVD) method. X-Ray diffraction patterns show that the CrO₂ films were pure rutile structure. Scanning electron microscopy(SEM) images indicate that the CrO₂ films consisted of submicron grains with a grain size of 250―750 nm. The magnetic researches reveal that the magnetic easy axis is parallel to the films, and at room temperature, the CrO₂ films show linear magnetoresistance.     

Simultaneous formation of platinum‐based nanocatalysts and degradation of dyes at oil/water interface: Comparative morphological and kinetic studies

To decrease the water pollution of textile industries with a large amount of toxic and non‐biodegradable colored dye effluents, an efficient technique is required to safely remove harmful pollutants. In this paper, the reaction between azo dyes and NaBH₄ catalyzed by nanoparticles (NPs) thin films has been studied. We report insitu degradation of methyl orange (MO) and methyl red (MR) by using Pt‐based thin films monitored by UV–Vis spectroscopy. We have synthesized different thin films such as Pt, PtPd, PtFeFe₂O₃, PtNi and PtAu films from Pt organometallic precursor in the MO and MR medium (dye degradation and NPs formation is happened simultaneously) and activity of these films were compared in the complete degradation of MO and MR dyes. Rate constants for the catalyzed reactions have been determined. PtPd NPs thin film has shown the highest rate constant for the degradation of MO and MR within only a few seconds due to its well‐ordered structure. Furthermore, the effect of presence of MO on the morphology of NPs was investigated.     

A comparative study of the polyaniline thin films produced by the cluster beam deposition and laser ablation methods

Polyaniline (PANI) thin films have been prepared by applying the novel neutral and ionized cluster beam deposition (NCBD and ICBD) methods and the pulsed laser deposition (PLD) technique to the PANI samples of half-oxidized emeraldine base (EB-PANI) and protoemeraldine base forms in a high-vacuum condition. Characterization of the oxidation states and structural changes of pristine and doped thin films has been performed by Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, and x-ray photoelectron spectroscopy. Spectroscopic measurements demonstrate that the dominant structure of NCBD and ICBD thin films corresponds to the reduced leucoemeraldine base state, whereas the chemical composition of PLD thin films depends critically on the laser fluence and the molecular weight of PANI target. The congruent deposition is only obtained for the PLD films deposited by the laser-induced decomposition of the low-molecular-weight targets in the low to intermediate fluence regime (below 100 mJ/cm2 with a pulse duration of 7 ns). The surface morphology examined by atomic force microscopy measurements shows that the cluster and laser beams are effective in producing smooth, uniform polymeric thin films. After I2 and HCl doping, the electrical conductivities of the NCBD, ICBD, and particularly PLD thin films are increased significantly. The higher conductivity of PLD films is ascribed to higher amounts of quinoid di-imine doping sites in the EB-PANI state, and the overall structure-conductivity characteristics are consistent with the spectroscopic observations.     

Microstructure analysis of sol‐gel‐derived nanocrystalline ITO thin films

The technique for ITO (Tin‐doped indium oxide) thin films by sol‐gel process is presented in this paper. After annealing at 500° for 15 min, ITO gel films get transformed into nanocrystallined indium tin oxide films. We studied the microstructure of ITO thin film which is closely related to optical and electrical properties. The microstructure of ITO thin film can be observed through high‐resolution transmission electronic spectroscopy (HRTEM) and the Fast Fourier Transform (FFT) technique. The film is nanocrystallite with grain sizes about 20 nm. Also, the surface chemical components were studied by XPS spectra. The transmission and the resistivity of ITO films is 97.0% and 3.5 × 10^?3 Ω?cm, respectively. Copyright © 2010 John Wiley & Sons, Ltd.     

Mechanoresponsive Self-Assembled Perylene Bisimide Films

In this work, self-assembled amino-acid appended perylene bisimides (PBIs) have been studied that when processed into thin films change their resistivity in response to being bent. The PBIs assemble into structures in water and form thin films upon drying. These normally delicate thin films can be tolerant to bending, depending on the aggregates they form. Furthermore, the films then reversibly change their resistivity in response to this mechanical stimulus. This change is proportional to the degree of bending of the film giving them the potential to be used quantitatively to measure mechanical movement, such as in wearable devices.     

Theoretical and experimental analyses of the deposited silver thin films

The silver thin films have been prepared using magnetron DC‐sputtering. We discuss in detail the thin films AFM images and their properties in different sputtering times of 2 to 6 minutes. Despite the low thickness of the films, the roughness saturation amounts, W_s, are well separated. The surface data do not follow the normal Family‐Vicsek scaling, and we have the local growth exponent, β(W_s(t)∼t^β). We obtained the global roughness scaling exponent α=0.36 and growth exponent, β=0.50. We also obtain the fractal spectrum of the data, f(α). The results show that the spectrum is right‐hook like. It distinguishes between different film thicknesses even in small sizes of hundreds of nanometers. Furthermore, we measure the surface conductivities and compare them to the thin film roughnesses. We investigate the roughness and fractality of the AFM data, looking for their relations to width and conductivity of the silver thin film samples.