Thickness Of Thin Films Research Articles

Determining the Characteristics of Ultrathin Polymer Films: A Spectroscopic Ellipsometry Approach.

Ellipsometry is a powerful and convenient technique that is widely used to determine the thickness and optical characteristics of polymer thin films. The determination is accomplished by modeling the measured change in the polarization of an electromagnetic wave upon interacting with the thin film. However, due to the strong statistical correlations between the fit parameters in the model, simultaneous determination of the thickness and the refractive indices of optically anisotropic ultrathin films using ellipsometry remains a challenge. Here, we propose an approach that can be used to obtain reliable values of both the thickness and the optical anisotropy of ultrathin polymer films. The approach was developed by performing spectroscopic ellipsometry measurements on thin films of hydrophobic polystyrene and hydrophilic chitosan of thickness between a few tens to a few hundred nm and whose absolute value of the birefringence differed by approximately an order of magnitude. Careful consideration of the characteristics of the root mean squared error of the fits obtained by modeling the ellipsometry data and the statistical correlations between the fit parameters formed the basis of the proposed approach.

Phase Transformations Driving Biaxial Stress Reduction During Wake‐Up of Ferroelectric Hafnium Zirconium Oxide Thin Films

AbstractBiaxial stress is identified to play an important role in the polar orthorhombic phase stability in hafnium oxide‐based ferroelectric thin films. However, the stress state during various stages of wake‐up has not yet been quantified. In this work, the stress evolution with field cycling in hafnium zirconium oxide capacitors is evaluated. The remanent polarization of a 20 nm thick hafnium zirconium oxide thin film increases from 9.80 to 15.0 µC cm−2 following 106 field cycles. This increase in remanent polarization is accompanied by a decrease in relative permittivity that indicates that a phase transformation has occurred. The presence of a phase transformation is supported by nano‐Fourier transform infrared spectroscopy measurements and scanning transmission electron microscopy that show an increase in ferroelectric phase content following wake‐up. The stress of individual devices field cycled between pristine and 106 cycles is quantified using the sin2(ψ) technique, and the biaxial stress is observed to decrease from 4.3 ± 0.2 to 3.2 ± 0.3 GPa. The decrease in stress is attributed, in part, to a phase transformation from the antipolar Pbca phase to the ferroelectric Pca21 phase. This work provides new insight into the mechanisms controlling and/or accompanying polarization wake‐up in hafnium oxide‐based ferroelectrics.

New surfactants based on soybean oil triglycerides, hexamethylenediamine and alkyl dihalides

The interaction of soybean oil triglycerides with hexamethylenediamine resulted in a nonionic surfactant – hexamethyleneamide of a mixture of soybean oil acids, which was then modified using alkyl dihalides (1,2-dibromoethane, 1,3-dibromopropane, and 1,5-dibromopentane). These reactions synthesized ionic surfactants. The composition and structure of the resulting amidoamine and its modifications with alkyl dihalides were identified using infrared spectroscopy. The obtained products were characterized by key physicochemical parameters. Conductometric measurements of aqueous solutions of the obtained salts with varying concentrations were also performed. It was found that with increasing concentration, the specific conductivity value increases, and these values are significantly higher than the specific conductivity of distilled water, indicating the ionic structure of the obtained substances. Surface activity was measured with a tensiometer using the Du Nouy ring method at the air-water interface. According to the determined surface tension values, surface tension isotherms were constructed. The stabilization of surface tension values for the nonionic surfactant occurs at 35.2 mN/m, while for the ionic surfactants, it occurs at values of 34.2, 34.0, and 33.2 mN/m, respectively. The colloid-chemical properties of the synthesized surfactants were studied, their adsorption characteristics were experimentally determined, and the most important colloid-chemical parameters were calculated, such as the critical micelle concentration, surface tension, maximum adsorption, minimum cross-sectional area of the molecule, surface pressure, adsorption efficiency, and the change in Gibbs free energy of the micellization and adsorption processes. Under laboratory conditions, the relative oil-collecting and oil-dispersing abilities of the obtained products were investigated using thin films (thickness <1 mm) of Balakhani oil on the water surface with different levels of salinity (seawater, freshwater, and distilled water). The synthesized surfactants were used in undiluted form and as 5% aqueous solutions. It was found that in seawater, the maximum oil dispersion coefficient, which indicates the degree of cleaning the water surface, is 91.1%. It is worth noting that transitioning from nonionic to ionic surfactants increases the duration of the reagents’ action.

Development of governing partial differential equations of reinforcing thin films

In this paper, a novel interface model for elastic isotropic thin films perfectly bonded to the surrounding elastic media is introduced. Considering an average stress and displacement through the thin film thickness, the shear stress discontinuity across the interface is expressed in terms of spatial and time derivatives of displacement components. The derived interfacial equations are presented in a general form. As such, they are applicable to asymmetric elastodynamic problems of anisotropic solids with thin film interfaces. Employing the introduced interface model and Hankel transform technique, static Green's functions of an elastic isotropic half-space reinforced by a buried thin film are obtained. Results of some special cases, including axisymmetric loading, inextensible membrane, unreinforced half-space, and surface-coated half-space, are also presented. The robustness and effectiveness of the proposed interface model are shown by two solved numerical examples, and some elastic responses are plotted to show the impact of thin film stiffness. According to the numerical results, modeling elastic thin films as inextensible membranes can significantly alter the elastic responses.

Electron Energy-Loss Spectroscopy Method for Thin-Film Thickness Calculations with a Low Incident Energy Electron Beam

In this study, the thickness of a thin film (tc) at a low primary electron energy of less than or equal to 10 keV was calculated using electron energy-loss spectroscopy. This method uses the ratio of the intensity of the transmitted background spectrum to the intensity of the transmission electrons with zero-loss energy (elastic) in the presence of an accurate average inelastic free path length (λ). The Monte Carlo model was used to simulate the interaction between the electron beam and the tested thin films. The total background of the transmitted electrons is considered to be the electron transmitting the film with an energy above 50 eV to eliminate the effect of the secondary electrons. The method was used at low primary electron energy to measure the thickness (t) of C, Si, Cr, Cu, Ag, and Au films below 12 nm. For the C and Si films, the accuracy of the thickness calculation increased as the energy of the primary electrons and thickness of the film increased. However, for heavy elements, the accuracy of the film thickness calculations increased as the primary electron energy increased and the film thickness decreased. High accuracy (with 2% uncertainty) in the measurement of C and Si thin films was observed at large thicknesses and 10 keV, where tλ≈1. However, in the case of heavy-element films, the highest accuracy (with an uncertainty below 8%) was found for thin thicknesses and 10 keV, where tλ≤0.29. The present results show that an accurate film thickness measurement can be obtained at primary electron energy equal to or less than 10 keV and a ratio of tλ≤2. This method demonstrates the potential of low-loss electron energy-loss spectroscopy in transmission electron microscopy as a fast and straightforward method for determining the thin-film thickness of the material under investigation at low primary electron energies.

Optical constants and thickness determination of La[formula omitted]Sr[formula omitted]MnO3 thin films on Nb:SrTiO3 substrates by spectro-ellipsometry: Combination of optical and X-ray techniques

40 nm thick La2/3Sr1/3MnO3 (LSMO) thin films were epitaxially grown by Pulsed Laser Deposition (PLD) onto niobium doped SrTiO3 (Nb:STO) substrates, with different Nb concentration from 0.01%wt to 0.5%wt. The optical characterization of the heterostructures by spectroscopic ellipsometry enables us to extract the optical constants of the manganite heteroepitaxial layer at room temperature. Performing spectrophotometry in the same wavelength range brings a useful cross-validation of the extracted results. In addition, the thickness evaluation of the LSMO layer by spectro-ellipsometry is further validated by both High Resolution X-ray diffraction and X-ray reflectivity, as well as a Transmission Electron Microscopy cross section, taken as a physical reference. This study validates quantitatively the spectro-ellipsometry as a suitable routine tool to measure accurately both thickness and complex refractive index of the LSMO thin film, picturing their peculiar electrical behaviour between both metallic and insulating phases. The relative error on the thickness measurement between X-ray and ellipsometry is less than 5%. The LSMO complex refractive index enabled also a simultaneous estimation of further material properties, such as the optical gap ωg or the mass density ρm, determined with less than 1.5% relative error compared to X-ray reflectivity results.

Principles of Measuring Thickness and Refractive Index of Thin Dielectric Film by Using Multiresonance Archimedean Spiral Metasurfaces with C Resonator in the Terahertz Frequency Range

Metasurfaces are an excellent platform for terahertz (THz) sensing applications, enabling highly efficient light–matter interaction and overcoming the fundamental disadvantage of the relatively long-wavelength THz range (30–3000 μm), which limits sensing of small features. The current focus in developing metasurfaces is mostly directed toward single-resonance metasurfaces and reconstruction of the dielectric constants of analyte from the saturation mode induced by the limited sensing volume of the metasurface. This paper presents a numerical demonstration of using a multiresonance metasurface to extract the thickness and refractive index of a deposited film without saturation of the sensor. It was shown that the multiresonance property enables determination of the analyte characteristic via measurements with two different thicknesses and tracking changes in two resonances. High-accuracy parameter retrieval is achieved when there are large differences in the thicknesses. In contrast to the established approach, this method provides an efficient way to avoid using relatively thick films.

Thickness measurement of thin films using atomic force microscopy based scratching

Thin-film thickness measurements using atomic force microscopy (AFM) comprise two steps: 1. AFM scratching in order to produce an exposed film edge, and 2. subsequent AFM measurement of the corresponding step height across the exposed edge. Although the technique is known, many open questions have limited its wider applications. In order to clarify the open questions, here we first demonstrate how to determine the normal force applied during the scratching in contact mode needed to completely remove films from substrates. In order to determine film thickness from processed AFM images, we discuss two procedures based on the histogram method and polynomial step-function fitting. Mechanisms of the scratching process are elucidated by the analysis of lateral forces and their enhancement during the film peeling. Phase maps of scratched domains recorded in amplitude modulation AFM (tapping) mode display a clear contrast compared to pristine films. Therefore, we suggest their utilization as simple indicators of spatial domains with completely removed films. As an example, here the measurements were done on polymer films fabricated by layer-by-layer deposition of oppositely charged polyelectrolytes composed of poly(allylamine hydrochloride) and poly(sodium 4-styrenesulfonate), while the applicability of the presented method on other materials is discussed in detail.

Identification of Elastoplastic Constitutive Model of GaN Thin Films Using Instrumented Nanoindentation and Machine Learning Technique

This study presents a novel inverse identification approach to determine the elastoplastic parameters of a 2 µm thick GaN semiconductor thin film deposited on a sapphire substrate. This approach combines instrumented nanoindentation with finite element (FE) simulations and an artificial neural network (ANN) model. Experimental load–depth curves were obtained using a Berkovich indenter. To generate a comprehensive database for the inverse analysis, FE models were constructed to simulate load–depth responses across a wide range of GaN thin film properties. The accuracy of both 2D and 3D simulations was compared to select the optimal model for database generation. The Box–Behnken design-based data sampling method was used to define the number of simulations and input variables for the FE models. The ANN technique was then employed to establish the complex mapping between the simulated load–depth curves (input) and the corresponding stress–strain curve (output). The generated database was used to train and test the ANN model. Then, the learned ANN model was used to achieve high accuracy in identifying the stress–strain curve of the GaN thin film from the experimental load–depth data. This work demonstrates the successful application of an inverse analysis framework, combining experimental nanoindentation tests, FE modeling, and an ANN model, for the characterization of the elastoplastic behavior of GaN thin films.

Optimization of Magnetic Tunnel Junction Structure through Component Analysis and Deposition Parameters Adjustment.

In this work, we focus on a detailed study of the role of each component layer in the multilayer structure of a magnetic tunnel junction (MTJ) as well as the analysis of the effects that the deposition parameters of the thin films have on the performance of the structure. Various techniques including atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to investigate the effects of deposition parameters on the surface roughness and thickness of individual layers within the MTJ structure. Furthermore, this study investigates the influence of thin films thickness on the magnetoresistive properties of the MTJ structure, focusing on the free ferromagnetic layer and the barrier layer (MgO). Through systematic analysis and optimization of the deposition parameters, this study demonstrates a significant improvement in the tunnel magnetoresistance (TMR) of the MTJ structure of 10% on average, highlighting the importance of precise control over thin films properties for enhancing device performance.

Effect of Boron-doping and annealing on the structure, morphological and optical properties of ZnO films prepared by spray pyrolysis method

Abstract This study investigates the influence of boron doping from boric acid (H3BO3) on the structural, morphological, and optical properties of ZnO thin films deposited on glass substrates via spray pyrolysis at a deposition temperature of 250 °C. Subsequently, they undergo annealing in air at varying temperatures (200, 300, and 400 °C) for 45 min. The research reveals a significant dependence of all investigated properties on both annealing temperature and boron doping. Both pristine ZnO and boron-doped ZnO (BZO) films exhibit a polycrystalline hexagonal wurtzite structure. At the highest annealing temperature (400 °C), both films demonstrate high optical transmittance exceeding 70%, with crystallite diameters ranging from 25.8 to 28.5 nm for ZnO and 15.96 to 24.80 nm for BZO. Additionally, both films exhibit pronounced absorbance up to 400 nm. Scanning electron microscopy (SEM) analysis confirms a uniformly thick film surface. As the annealing temperature increases, the crystallite size grows, particle morphology evolves, and the overall film thickness increases. Fourier transform infrared (FTIR) spectroscopy validates the successful incorporation of boron atoms into the ZnO lattice structure. No contaminant peaks are observed in the FTIR spectra, indicating film purity. Furthermore, the study finds that BZO films possess a narrower optical band gap compared to pristine ZnO films. The band gap of the as-deposited and annealed BZO films is measured to be 3.04 eV and 2.9 eV, respectively, which is lower than the 3.23 eV band gap observed for the ZnO film. In general, the band gap exhibits a decreasing trend with increasing annealing temperature.

Characterizing oxidation, thickness, and composition of metallic glass thin films with combined electron probe microanalysis and X-ray photoelectron spectroscopy

Metallic glass thin films (MGTFs) are a recently developed class of alloy coatings with potential applications ranging from biomedical devices to electrical components. Their tribological performance in service conditions is dictated by MGTF bulk composition but can be limited by the native oxide surface that inevitably forms upon exposure to atmosphere. Surface oxidation, thickness, and composition of ZrCuNiAl MGTFs were characterized using a combination of X-ray photoelectron microscopy (XPS) and electron probe microanalysis (EPMA). MGTF samples with nominal thicknesses of 50, 500, and 1500 nm were sputtered onto Si and SiN wafer substrates within a high vacuum deposition chamber and their amorphicity was confirmed by X-ray diffraction. XPS depth profiling identified the thin film composition and showed that the surface oxide was dominated by a mixed layer of mostly ZrO2, a little oxidized Al, and some metallic Zr. EPMA X-ray intensities were acquired as a function of beam energy to excite characteristic X-rays from different depths of the MGTFs and reconstructed using open-source thin film analysis software BadgerFilm, to determine the composition and thickness of sample layers. EPMA results constrain the composition to be Zr54Cu29Al10Ni7 within 0.7 at. % variation and total thicknesses to be 49, 470, and 1546 nm. Using the oxide composition identified from XPS depth profiling as an input for BadgerFilm analysis, EPMA results indicate the surface oxidation layer on each of the thin film samples was 6.5 ± 1.1 nm thick and uniform across a 0.25 mm region of the film.

Penetration depth and critical fields in superconducting NbTi thin films grown by co-sputtering at room temperature

We present a study on the superconducting properties of 300 nm thick NbTi thin films grown by co-sputtering on silicon substrates at room temperature. The samples exhibit a Nb (50 at%) and Ti (50 at%) chemical composition, revealing a polycrystalline structure textured along the (110) axis of the body-centered cubic structure. The measured superconducting critical temperature (T c ) was 9.65 K, and the upper critical field extrapolated to zero temperature reached approximately 15 T, resulting in a coherence length at zero temperature of approximately 4.7 nm. The penetration depth was determined through local magnetic force microscopy measurements conducted at temperatures from 4.25 to 7 K. The obtained values range from (250 ± 15) nm at 4.25 K to (370 ± 20) nm at 7 K. Extrapolating these measurements to zero temperature, we obtained an estimated value of (230 ± 20) nm. To extend the performance and potential applications of NbTi, we additionally grew a 150 nm thick sample on flexible polyimide. In this case, we observed that the films preserved their superconducting properties, displaying a decrease in T c to 9.2 K and a similar upper critical field compared to samples grown on silicon. The feasibility of growing NbTi alloys at room temperature, with superconducting parameters comparable to or superior to metallic Nb for the upper critical field, renders this system promising for cryogenic applications, particularly in the development of high-performance electronic devices on both rigid and flexible substrates.

The structural, optical, electrical and radiation shielding properties of Co-doped ZnO thin films

Co:ZnO thin films are promising due to the similar ionic radii of cobalt and ZnO, and their potential for carrier spin injection, transfer, and detection. This study aims to investigate the structural, optical, electrical, and radiation shielding properties of Co-doped zinc oxide (Co:ZnO) thin films for potential applications in various fields such as semiconductors, solar cells, spintronics, and radiation shielding. The effect of commercially available Cobalt acetate tetrahydrate and Cobalt complex (Co with conjugated NN ligand) as cobalt additives on the synthesis of ZnO thin films is compared, aiming to discern their respective impacts. The dopants are incorporated in 2, 4, and 6 wt%, employing the sol-gel spin coating method.Applying cobalt complex additive as Co precursor resulted in ZnO:Co films with a superior enhancement of the electronic band gap of 2.84–3.00 eV compared to cobalt acetate precursor (2.62–2.84 eV). With the introduction of Cobalt, there is a notable change in the electrical conductivity, showcasing a decrease from 1.5x10−7 to 2.11x10−10 (S/cm). Also, radiation shielding parameters were experimentally measured in the energy range of 186.1–1764.5 keV within the scope of gamma ray spectral analysis. Exposure buildup factors (EBF) in the energy range of 15–15,000 keV were calculated up to 1–40 mean free path (mfp). Mass stopping power (MSP) and projected range values (PR) for nuclear safety applications were calculated for protons and alpha particles using the SRIM code. Thin film thicknesses were determined by using Lambert-Beer law. It was observed that the thin film thicknesses obtained from gamma spectrometry (2.090–2.628 μm) and SEM (2.157–2.725 μm) were compatible with each other.

Low-temperature deposition of β-Ga2O3 thin films employing in situ pulsed laser-assisted RF sputtering system

Monoclinic β-phase Ga2O3, the most thermodynamically stable phase, is an interesting material for power electronics applications. In this study, we present an efficient approach, diverging from existing methods, for the successful deposition of β-Ga2O3 thin films at low substrate temperatures without any post-annealing. Instead of relying on high substrate temperatures, we supplied sufficient thermal energy to the substrate by directly irradiating it with a 1064 nm ytterbium pulsed laser during RF sputtering. This eliminated the need for post-annealing and significantly reduced processing time. It also allowed for excellent control over the crystal structure and crystallinity formation of the thin films by providing excellent particle energy through heat transfer on the surface. The X-ray diffraction (XRD) scan of the sample deposited by irradiating a pulse laser to the substrate shows only three peaks corresponding to (−201), (−402) and (−603) of β-Ga2O3, indicating superior crystalline quality. The sample deposited at 2.5 mTorr working pressure maintained a thin film thickness of 207 nm and a grain size of 40.07 nm, and the energy band gap of the thin films was measured in the range of 4.45–4.64 eV. XPS, Auger, and PL optical analysis observed characteristic core-level peaks of β-Ga2O3 and the suppression of oxygen vacancies due to the high binding energy. The oxygen content increased by 4.39 %, resulting in the O/Ga ratio rising to 1.19, which leads to a positive shift in the O 1s binding energy. Consequently, we demonstrated the induction of phase transition of Ga2O3 into a stable β phase by introducing an in-situ pulse laser process during low temperature RF sputtering. These results have significant potential in various applications and are expected to contribute significantly to technological advancements.

Numerical ellipsometry: Artificial intelligence for rapid analysis of indium tin oxide films on silicon

Ellipsometry is a well-known material analytical method widely used to measure thickness and optical properties of thin films and surfaces across a wide range of industrial and research applications including critical dimensions in chipmaking. The method employs the fact that light undergoes a change in polarization state upon reflection from or transmission through a material. The desired properties of the surface structure are related to measurements by the electromagnetic models expressed by Maxwell’s equations as well as models of material properties. The work here demonstrates the use of artificial intelligence in the form of a multilayer perceptron artificial neural network to apply the electromagnetic model. The reflecting surface examined here is composed of indium tin oxide (ITO) films approximately 400 nm in thickness deposited on silicon substrates. Solutions are provided by 299 artificial neural networks, one per wavelength from 210 to 1700 nm across which ITO exhibits transparent as well as absorbing characteristics. Thus, it serves as a proxy for a wide range of other materials. To train the network, simulated measurements are computed at two thicknesses which differ randomly by 1–6 nm and at three different incidence angles of 55°, 65°, and 75°. Following training, results are obtained in less than one second on a conventional desktop computer.

Enhancement of ferroelectricity in chemical-solution-deposited ZrO2 thin films through fine phase transition control

Recent studies have highlighted the ferroelectric potential of ZrO2 thin films, which offer advantages over HfO2-based ferroelectric materials, such as lower thermal budget and greater natural abundance. In this research, pure ZrO2 ferroelectric thin films were fabricated on Si substrates using chemical solution deposition with all-inorganic precursors. We explored the impacts of film thickness and HfO2 seed layers on phase transition and ferroelectric properties. Notably, an 11 nm thick ZrO2 film exhibited ferroelectric behavior with a remanent polarization of 12.6 μC/cm2. Due to the combined effects of tensile stress and surface energy, the increase in thickness to 30 nm led to a phase transition from the orthorhombic phase to the monoclinic phase and a resultant decrease in remanent polarization. Additionally, the introduction of a HfO2 seed layer facilitated the crystallization of the ferroelectric o-phase, enhancing the remanent polarization to 16.5 μC/cm2 in our ∼8 nm thick ZrO2 thin film with a ∼2 nm thick HfO2 seed layer. These findings provide valuable insights into optimizing ferroelectric properties in ZrO2 thin films through phase transition control.

Highly crystalline yttria‐stabilized zirconia and titania thin films on plastic substrates via sol‐gel transfer process

AbstractWe prepared yttria‐stabilized zirconia (YSZ) and titania crystalline thin films on polycarbonate (PC) substrates by the sol‐gel transfer technique that we have developed recently. Precursor gel films were deposited by spin‐coating on a polyimide/polyvinylpyrrolidone mixture layer on Si(100) substrates, and then were calcined at 600°C. The spin‐coating and the calcination were cycled, followed by final firing at 600–1000°C, to obtain 140–190 nm thick, YSZ and titania crystalline thin films. The film densification progressed as the final firing temperature increased, where the porosity calculated from the refractive index decreased down to a few percent. The film thus obtained was heated at 190°C on a hot plate, and a PC substrate was pressed on the film to transfer it to the PC substrate. The transferability quantified by image analysis of the film area was found to be significantly different between the YSZ and titania films. In the case of YSZ films, the area of silicon that was fractured and adhered to the transferred film increased significantly with increasing firing temperature, leading to a decrease down to 0% in the fraction of the successful transfer area without such a damage. On the other hand, the fraction of the successful transfer area remained around 90% irrespective of the firing temperature for the titania films. The surface of the titania films that were fired at 800–1000°C and transferred to PC substrates had voids of several tens nm scale, which may have been formed during anatase‐to‐rutile phase transformation. We thought that the reduced titania/Si(100) contact area due to such void formation facilitated the delamination of the titania films from Si(100) substrates. High temperature firing, which promotes crystallization and densification of films, thus affects differently the film transferability to plastic substrates, depending on the type of films. The work also suggested possible use of titania films as release‐assisting layers.

Photoresponse in sequentially stacked antimony selenide thin films

Antimony selenide (Sb2Se3), a binary semiconducting compound has widespread research attention due to its excellent optoelectronic properties in the visible region and usefulness in applications such as solar cells, photosensors and photoelectrodes. The presented study explores the thickness dependent photoresponse in Sb2Se3 thin films, prepared by reactive selenization of antimony films having thickness values of ∼938 nm and ∼1879 nm when stacked second time. Growth orientation along [001] direction was achieved through carefully optimized selenization conditions to enable favourable charge transport in anisotropic Sb2Se3. Predominant Sb2Se3 formation was inferred from x-ray diffraction, Raman spectroscopy, secondary electron microscopy and energy-dispersive X-ray analyses. High optical absorption coefficient values of about 1 × 105 cm−1 and 5.7 × 104 cm−1 were observed for ∼938 nm and ∼1879 nm thick Sb2Se3 thin films. Further, the optoelectronic properties were elucidated through current–voltage and transient photoresponse measurements under dark and illumination conditions. The measurements were done under zero and different bias voltages. Sb2Se3 films having∼ 938 nm thickness exhibited self-driven photoresponse with a responsivity of 4.3×10−8 A W−1 and detectivity of 3.5 × 106 jones respectively, under AM 1.5 G illumination conditions.

Nanostructuring, fractal characterization and wettability of ion irradiated Au thin films and their thickness effect

This study proposes a method for modifying the wettability of Au thin films of thicknesses 5 nm and 10 nm on Si substrates using 8 keV Ne ion beam irradiation at different fluences, thereby enabling surface wettability adjustment at the nano-scale and its thickness dependence. This advancement would be highly beneficial for applications such as high-resolution printing and nano-biotechnology. The contact angle of the irradiated region for the 5 nm thin film changed from hydrophobic to hydrophilic with increasing ion dosage, whereas for the 10 nm thin film, it changed from hydrophilic to hydrophobic under the same conditions. Fractal analysis was performed on pristine and ion beam modified surfaces to investigate the underlying nano-structuring process, with reported values for average roughness (Ra), Hurst exponent (H), fractal dimension (Df), contact angle (CA), and wettability at different ion dosages. Atomic Force Microscopy and Rutherford Backscattering Spectroscopy were used to examine surface roughness and depth profile. The process of sputtering becomes crucial when the ion range approaches the thickness of thin films, with the sputter yield showing dependence on the thickness of thin films at different ion fluence levels. Monte Carlo simulations SRIM/TRIM and TRIDYN were used for comparison with the experimental results, with TRIDYN taking into account dynamic changes in the target's morphology and composition.