Grain Size Of Films Research Articles

Effect of hydrogen sulfide concentration on two-dimensional SnS2 film by atomic layer deposition in annealing process

Two-dimensional materials are widely studied due to its unique physical, optical, electrical properties, and good compatibility with various synthesis methods. And among the many fabrication methods, tin disulfide (SnS2) material, a two-dimensional (2D) material that can be achieved with accurate thickness control using atomic layer deposition (ALD), high uniformity and conformality even at low process temperatures is attracting attention. However, since the crystallinity of the thin film is low at a low process temperature, various post-annealing methods are being studied to compensate for film quality. In this work, we compared the crystal structures, chemical binding energies, and electrical properties of the thin films by post-annealing SnS2thin films according to the hydrogen sulfide concentrations of 4.00% and 99.99% in the hydrogen sulfide atmospheres. The crystallinity, grain size, and carrier concentrations of the SnS2thin film were the highest at a post-annealing temperature of 350 °C at a hydrogen sulfide concentration of 99.99%, and the chemical binding energies also corresponded with the standard Sn4+states, forming a pure 2D-hexagonal SnS2phase. In addition, SnS2thin films deposited via ALD showed high uniformity and conformality in large-scale wafers and trench structure wafers.

Bulk Heterojunction Perovskite Solar Cells Incorporated with Conjugated Polyfluorenes

Ambipolar transport characteristics of metal halide perovskites (MHPs) enable both hole and electron to be transported simultaneously in perovskite solar cells (PSCs); however, unbalanced charge transport is a fundamental limitation in boosting power conversion efficiency (PCE) of PSCs. Compared to the PSCs with either n–i–p or p–i–n device structures, bulk heterojunction (BHJ) PSCs, inspired by organic photovoltaics, are recognized as superior for balancing charge transport and maximizing interface interactions. This study reports high‐performance BHJ PSCs, where the BHJ composites are composted with the n‐type MHPs mixed with the p‐type conjugated polyfluorenes. In the systematic studies, it is indicated that a small amount of conjugated polyfluorenes component can boost the crystallinity and grain size of the MHP thin film. Moreover, BHJ composite thin films possess boosted charge carrier mobility and a tendency of balanced charge transport and suppress both radiative and non‐radiative charge carrier recombinations. Most importantly, an efficient photoinduced charge transport within the BHJ composite thin film boosts photocurrent. As a result, the PSCs based on the n‐type MHPs:p‐type conjugated polyfluorenes BHJ composite thin film exhibit 23.46% of PCE and boost stability. The results demonstrate a facial method to approach high‐performance PSCs.

Influence of sulfurization process in tin sulfide and sulfur mixed vapors on the morphology of Cu2SnS3 thin films

Abstract Cu2SnS3 (CTS) is expected to be an absorber material for next-generation solar cells because it is composed of nontoxic, low-cost elements and has an absorption coefficient of >104 cm−1. In this study, the effects of sulfurization in tin sulfide (Sn x S y ) and S mixed vapors on various properties of CTS were investigated by using a 3-zone tube furnace to suppress carrier recombination at the grain boundaries and control the composition of the CTS. The CTS deposited via sulfurization in S vapor only (1-zone CTS) contained different monoclinic and tetragonal CTS structures. The grain size of the CTS thin films deposited via sulfurization in Sn x S y and S mixed vapors was not increased. On the other hand, crystal structure analysis revealed that the CTS had grown to single-phase monoclinic CTS. The results suggest that precipitation in Sn x S y and S mixed vapors contributes to the growth of monoclinic CTS with suitable power-generation characteristics. This finding is important for realizing high-efficiency CTS-based solar cells.

Structural and Optical Characterization of Cu2Se0.8S0.2 Thin Films Deposited by Thermal Evaporation

Abstract A simple cost thermal evaporation deposition technique was used to prepare of Cu2SeS thin films on the substrates made of glass at RT with thickness ( 500 + − 20 ) nm . Structural, and optical properties of these films were investigated. The films were structurally characterized using X-ray diffraction XRD analyses, the film samples were morphologically characterized using atomic force microscopy (AFM), and optical UV-Vis spectroscopy was also to characterize the samples. The films have been treated at deferent temperatures (403, 453 &503) K for 1 hour, X-ray diffraction (XRD-with wavelength 1.54 A) study the structure properties of this films suggest a cubic structure and have prominent (111) orientation. AFM analysis, it is evident that Cu2SeS film is polycrystalline in nature, and that crystallite size and average grain size for films after annealing were increasing. The optical absorption coefficient (α) of the film was evaluated using absorbance spectra in the wavelength range (400-1100) nm. The direct band gap of about 2.2 eV, decrease by increasing annealing temperature, The structure and the optical characteristics of these films may have practical applications in renewable energy.

Effect of boron doping levels on the piezoresistive properties of boron-doped diamond films prepared by HFCVD

The exceptional piezoresistive properties of boron-doped diamond (BDD) films render them highly promising for pressure sensor applications. These properties are closely associated with the doping concentration, crystal structure, and substrate material. In this study, BDD films with varying boron concentrations (B/C=500-8000 ppm) were fabricated on silicon and diamond substrates using hot-filament chemical vapor deposition (HFCVD) equipment. The relationship between surface grain characteristics, grain boundaries, and gauge factor (GF) of BDD films deposited on different substrates was systematically examined. The concentration of boron doping significantly influenced the surface morphology, electrical resistivity, and GF of the BDD films. The grain size of BDD films initially increased as the boron doping concentration was raised from 500 ppm to 2000 ppm; however, it subsequently decreased when the boron doping content exceeded 2000 ppm. Moreover, we found that the piezoresistive impact of a BDD film is strongly correlated to its grain size; larger grain sizes result in higher GF values. Notably, compared to those on silicon substrates, the BDD films deposited on diamond substrates exhibited superior piezoresistive characteristics. Specifically at a doping concentration of 2000 ppm, a GF as high as 284 was achieved for the BDD film on a diamond substrate compared to only 140 for that on a silicon substrate.

Investigating optical, structural and morphological properties of CuxZn1-xS thin films

Abstract CuxZn1-xS (CZS) Nano crystallized thin films with (x=0.25,0.5,0.75) were grown from alloy by thermal evaporation technique on glasses substrates at room temperature in a vacuum ∼ 2 × 10 −5 mbar with 450±20 nm thickness. The Cu content concentration effects on structure, morphology besides optically property of these films were investigated. X-ray diffraction (XRD) technique and Atomic force microscopy (AFM) were used to investigation the structural and morphological properties of CuxZn1-xS films. XRD analysis offered that these films had poly crystalline hexagonal structure with preferred orientation along (201) plane and mixed of of CuS-ZnS structure. The crystallites size changing with Cu concentration were found as (4.12, 5.5, 8.4) nm respectively. Using AFM measurements to investigate morphological properties of these films, the grain size for CuxZn1-xS films differs with Cu content thru uniform distribution. UV-Vis absorption spectroscopy was used to investigation the optical characterization of CuxZn1-xS films as a function of Cu content. The direct band gap values of these films were found decrease with increasing Cu content as (2.45, 2.4, and 2.3) eV respectively and the optical constant affected with Cu content. The CuxZn1-xS films have suitable optical characteristics which can used it for solar cell applications.

The structural characteristics of nano-copper thin films produced via laser-assisted electric wire explosion process

Abstract Due to the wide range of important applications, the metal and metal oxide nanoparticles have increasing demand, so that many methods and technologies attempted to produce it. The Electric Wire Explosion (EWE) method is the most established method to produce nanometals and metal oxides in the form of either powders or thin films. In this study, copper and copper oxide films were prepared via electric wire explosion method with a developed laser igniting spark gap switch. The Cu thin films were prepared at different explosion voltages (4, 5 and 7kV) and then their structural properties were studied. The results show that the produced copper/copper oxides nanoparticles of thin films increased as the exploding voltage increased. The XRD test shows that the films crystallite size increased as the exploding voltage increased. FE-scanning electron microscope (FE-SEM) images, are shows the decrease of grain size of thin films as the explosion voltage increase.

Enhanced cross-interfacial growth by thickening transition layers and tailoring grain size of columnar nanotwinned Cu films

Electrodeposited <111>-oriented nanotwinned Cu (NT-Cu) films consist of micron-scale columnar grains and they are thermally stable up to 400 °C. By adding nanoscale equiaxed Cu grains at the bottom of the NT-Cu films, anisotropic large grain growth could be triggered below 200 °C. The grains grew over 50 μm in bonded Cu–Cu films with 5.7 μm thick. Two main factors are identified for the low thermal stability and large grain growth behavior. The grain refining and transition layer thickening are effective to lower the thermal stability of the NT-Cu and reduce the required temperature for recrystallization and grain growth in the NT-Cu film. By increasing the fine-grained layer and refining the grain size of the columnar twinned grains, anisotropic grain growth can occur at 150 °C. The low thermal stability NT-Cu can be employed to completely eliminate the bonding interface at low temperatures in Cu–Cu joints. However, when the fine-grained layer is thicker than a threshold value, normal grain takes place and the bonding interface remains. The mechanism of anisotropic large grain growth was also proposed.

Structure, morphology and magnetic performance of (Fe65Co35) x @(Ni0.5Zn0.5Fe2O4)100–x nanocomposite thin films

A bi-magnetic phase (Fe65Co35)x@(Ni0.5Zn0.5Fe2O4)100–x nanocomposite thin film was created by combining Fe65Co35 alloy nanoclusters produced through plasma gas condensation with Ni0.5Zn0.5Fe2O4 thin film prepared via RF magnetron sputtering. The study revealed that the Fe65Co35 alloy nanoclusters, with an average particle size of approximately 6 nm, are surrounded by the amorphous ferrite phase, forming a granular ‘core–shell’ structure. As the proportion of Fe65Co35 alloy nanoclusters increased from 5.9 wt% to 35.4 wt%, the grain size of the nanocomposite thin films decreased from 24 nm to 10.4 nm. Magnetic analysis demonstrated that the nanocomposite thin films displayed soft magnetic properties at room temperature. With an increase in Fe65Co35 content, the saturated magnetization of the nanocomposite thin films escalated from 68 emu cm−3 to 214 emu/cm3, significantly surpassing that of the corresponding NiZn ferrite films (∼17 emu/cm3). The fluctuation of coercivity is intricately linked to the grain size of the nanocomposite thin films, and at 24.5 wt% of Fe65Co35 alloy nanoclusters, the coercivity is minimized to 14 Oe. The ferromagnetic resonance spectra of the nanocomposite films exhibited some asymmetric broadening and shift. As the Fe65Co35 content increased, the resonance field initially decreased and then rose, while the resonance linewidth gradually decreased.

From weak to strong-coupling superconductivity tuned by substrate in TiN films

Abstract The interplay between substrates and superconducting thin films has attracted increasing attention. Here, we report an in-depth investigation on superconducting properties of the epitaxial TiN thin films grown on three different substrates by dc reactive magnetron sputtering. The TiN films grown on (0001) sapphire exhibit (111) crystal orientation, while that grown on (100) Si and MgO substrates exhibit (100) orientation. Moreover, the samples grown on Si reveal a relatively lower level of disorder, accompanied by the higher critical transition temperature Tc and smaller magnitude of upper critical field slope near Tc. Remarkably, we uncovered a rather high value of superconducting gap (with Δ0/kBTc = 3.05) in TiN film on Si indicating a very strong coupling superconductivity, in sharp contrast to the case using sapphires and MgO as the substrate which reveals a weak-coupling feature. The comprehensive analysis considering the scenarios of the three substrate shows that the grain size of the thin films may be an important factor influencing the superconductivity.

Control polarity of gallium nitride on Si (1 1 1) using atomic layer annealing and thermal atomic layer deposition

Ga-polar GaN thin films and N-polar GaN thin films were fabricated by using thermal ALD and plasma assisted ALA processes, respectively. The polarity of GaN wurtzite thin films was determined by cross-sectional STEM analysis of as-deposited films and top-view SEM images after KOH wet-etching. The crystallinity and grain size of thermal ALD GaN were drastically increased with the GaN ALA buffer layer. The ALA Ar plasma pulse in each ALD cycle decreased the oxygen and carbon impurity content and improved the crystallinity of GaN thin films by removing organic ligands. High purity GaN thin films were successfully deposited on oxide-free Si (111) substrate by using the ALA process with 100 ms of TDMAGa with push gas, 3 × 800 ms of N2H4, and 15 s of 25 W ALA plasma pulse with −25 V stage DC bias at 275 °C. The lowest FWHM value (0.59°), smooth surface morphology (RMS=1.0 nm), and 10–20 nm grain size of columnar GaN thin films were obtained by tuning process parameters.

Development of photovoltaic and photodetection characteristics in CdS/P3HT devices through Al-doping

CdS thin films were deposited by chemical bath deposition onto FTO substrates with Al concentrations of 0, 1, 3, 5 and 6 %. X-ray diffraction revealed introduction of 1 % Al-doping reduced dislocation density and enhanced the crystal quality of CdS. Scanning electron microscopy confirmed a reduction in grain size in Al-doped CdS films compared to CdS. N3 and P3HT layers were spin-coated onto the prepared substrates, respectively. The fabrication of the solar cells was completed using Ag silver paste for the top contact. The lowest photoluminescence peak intensity was achieved for CdS (3 %Al):P3HT solar cell, indicating efficient exciton dissociation. 3 % Al-doped CdS-based device exhibited the highest efficiency at 0.210 %, nearly seven times that of reference device. CdS (3 %Al):P3HT device demonstrated the best photodetection characteristics, with a responsivity of 2.2 × 10-2 A/W, detectivity of 3.3 × 108 Jones, response time of 13 ms, and recovery time of 12 ms at zero bias voltage.

Fabrication of Silica–Titanium Composite Film on Wood Surface and Optimization of Its Structure and Properties

In this thesis, wood loaded with a silica–titanium (Si-Ti) composite film was prepared using the sol–gel method in order to achieve improved wood with high hydrophobicity and photocatalytic activity under visible light. The factors affecting the structure and properties of the composite film, as well as the optimization process, were discussed. Infrared analysis revealed that the vibrational intensity of Si-O-Si, Ti-O-Ti, and Ti-O-Si telescopic vibration peaks increased with an increase in vinyltriethoxysilane (VETS). Additionally, the number of Ti-O-Ti telescopic vibration peaks also increased with an increase in VETS. Furthermore, the intensity of -NO3, Si-O-Si, and Ti-O-Ti telescopic vibrational peaks was enhanced with a higher dosage of nitric acid. Conversely, the intensity of -OH telescopic vibrational peaks decreased with an increase in drying temperature. XRD analysis showed that nitric acid could promote the transformation of TiO2 from amorphous to anatase, while SiO2 would reduce the grain size of anatase TiO2 and promote the growth of rutile TiO2. Additionally, wood surfaces loaded with Si-Ti composite film changed from hydrophilic to hydrophobic, with significant differences observed between different levels of each factor. The photocatalytic activity of surface-loaded Si-Ti composite films on wood was most affected by the amount of nitric acid, which influenced crystallinity of TiO2 and thus impacted the photocatalytic activity. Furthermore, changes in VTES dosage not only affected the crystalline phase of TiO2 and the grain size of Si-Ti composite film but also influenced the crystallinity of TiO2 through generating SiO2. Finally, based on optimal preparation process (titanium–alcohol ratio of 1:5, titanium–silicon ratio of 1:0.2, titanium–acid ratio of 1:0.5, and drying temperature of 100 °C), wood surfaces loaded with Si-Ti composite film achieved a contact angle up to 125.9° and exhibited a decolorization rate for rhodamine B under UV light reaching 94% within 180 min.

Bidirectional UV/violet heterojunction light-emitting diode with In0.27Al0.73N alloy film as electron transport layer

In this paper, the p-GaN/n-In0.27Al0.73N heterojunction light-emitting diode (LED) was fabricated by radio frequency magnetron sputtering (RF-MS) and the electroluminescence (EL) characteristics of the p-GaN/n-In0.27Al0.73N heterojunction diode was investigated. Based on the preparation of the InXAl1-XN thin films at different substrate temperatures (Ts), the crystal structure, optical and electrical properties were investigated by XRD, SEM and other material characterization techniques. With increasing Ts, the grain size and surface morphology of the InXAl1-XN thin films change dramatically. The film has the best optical and electrical properties when the Ts is 300℃. On the basis of this, the compositional content of indium in the InXAl1-XN film was calculated to be 0.27. The heterojunction LED was fabricated on a commercial p-GaN substrate and the In0.27Al0.73N alloy film. The EL was successfully achieved at various forward and reverse voltages at room temperature and the temperature-dependent EL has been investigated. Furthermore, research is being conducted on the characteristics of the interface of p-GaN/n-In0.27Al0.73N heterojunction and the elucidation of the light-emitting mechanism of diode. The present work uses a simple and low-cost RF-MS method to fabricate UV/Violet bidirectional drive p-GaN/n-In0.27Al0.73N heterojunction LED, which provides a new reference for the fabrication of LED using InXAl1-XN alloy material.

The effect of grain size on diode parameters of Ag/p-NiOx/n-Si/Al based Schottky diode

The effect of grain size on optical properties and designed Ag/p-NiOx/n-Si/Al-based Schottky diode have been investigated. The XRD patterns are used to calculate the grain size of NiOx film, which increases with increasing thickness. Fractal dimensions were estimated from the power spectral density (PSD) algorithm using AFM images. The band gaps were calculated from recorded transmission spectra, showing the reduction of band gap from 3.88 eV to 3.67 eV with increasing grain size. The effect of grain size on the performance of Ag/p-NiOx/n-Si/Al-based Schottky-diodes are analyzed through I-V measurement. The diode parameters of the designed device were calculated using the thermionic emission, Norde, and Cheung models. It is found that the reduction of barrier height of the Schottky diode from 0.95 eV to 0.84 eV with increasing grain size of NiOx films. It is found that the grain size of film strongly impacted on the diode parameters, such as ideality factor (η), potential barrier (φh), series resistance (Rs) performance.

Effects of HiPIMS Duty Cycle on Plasma Discharge and the Properties of Cu Film.

In this paper, Cu thin films were deposited on Si (100) substrates by the high-power impulse magnetron sputtering (HiIPMS) technique, and the effects of different duty cycles (from 2.25% to 5.25%) on the plasma discharge characteristics, microstructure, and electrical properties of Cu thin films were investigated. The results of the target current test show that the peak target current remains stable under 2.25% and 3% duty cycle conditions. Under the conditions of a 4.5% and 5.25% duty cycle, the target peak current shows a decreasing trend. The average power of the target shows a rising trend with the increase in the duty cycle, while the peak power of the target shows a decreasing trend with the increase in the duty cycle. The results of OES show that with the increase in the duty cycle, the total peak intensity of copper and argon emissions shows an overall increasing trend. The duty cycle from 3% to 4.5% change in copper and argon emission peak total intensity change is not obvious. The deposition rate and surface morphology of the copper film were investigated by scanning electron microscopy, and the deposition rate of the copper film increased with the increase in the duty cycle, which was mainly due to the increase in the average power. The surface roughness of the copper film was evaluated by atomic force microscopy. X-ray diffraction (XRD) was used to analyze the grain size and texture of the Cu film, and the results showed that the average grain size of the Cu film increased from 38 nm to 59 nm on the (111) and (200) crystal planes. Four-probe square resistance test copper film resistivity in 2.25%, 3% low duty cycle conditions of the copper film resistivity is generally higher than 4.5%, 5.25% high duty cycle conditions, the copper film resistivity shows the trend of change is mainly affected by the copper film grain size and the (111) face of the double effect of the optimal orientation. The lowest resistivity of the copper film measured under the 4.5% duty cycle condition is 1.7005 μΩ·cm, which is close to the intrinsic resistivity of the copper film of 1.67 μΩ·cm.

Impact of crystallinity on thermal conductivity of RF magnetron sputtered MoS2 thin films

This study investigates the effects of sulfur atomic defects and crystallinity on the thermal conductivity of MoS2 thin films. Utilizing scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), and Raman spectroscopy, we examined MoS2 films, several nanometers thick, deposited on Si/SiO2 substrates. These films were prepared via a combination of RF magnetron sputtering and sulfur vapor annealing (SVA) treatment. Structural analyses, including cross-sectional STEM and in-plane and out-of-plane XRD measurements, revealed an increase in the S/Mo ratio and grain size of the MoS2 films following SVA treatment. Notably, the in-plane thermal conductivity of MoS2 films treated with SVA was found to be at least an order of magnitude higher than that of films without SVA treatment. This research suggests that the in-plane thermal conductivity of MoS2 thin films can be significantly enhanced through crystallinity improvement via SVA treatment.

Influence of grain size on electromechanical properties of (Ba,Ca)(Zr,Ti)O3: A multiscale analysis using spark plasma sintering and aerosol deposition

The piezoelectric and ferroelectric properties of aerosol deposited (AD) thick ceramic films are significantly reduced in comparison to bulk materials, which is assumed to be largely related to the nanometer-sized grains (∼0.01 μm) observed in the resulting microstructures. This work, therefore, focuses on understanding the role of grain size in electromechanical properties within the range of AD films based on Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT). In a comprehensive compilation of the piezoelectric constant (d33) of samples from various studies the grain size dependency of the d33 was shown for the lead-free ferroelectrics BCZT, BaTiO3, and (K,Na)NbO3. In this, it can be seen that no BCZT sample with a grain size below 0.4 μm was analyzed regarding their d33 before, thereby leaving a gap to the grain size of AD films. In this study, the grain size of ceramic bulk samples was varied using spark plasma and conventional sintering (0.1 μm – 11 μm) and their properties compared to those of AD films. To enable the fabrication of bulk samples in the same range as AD films, a hydrothermal powder with an average particle size of 0.075 μm was synthesized. A continuous increase of the permittivity, the polarization, and the piezoelectric coefficient was observed through grain size increase. These results suggest that the grain size of AD films needs to be enhanced to improve their properties. Importantly, the insights of this multiscale analysis on the grain size can help to tailor also the properties of other BCZT films and bulk samples.

Image-driven machine learning for automatic characterization of grain size and distribution in smart vanadium dioxide thin films

This study focuses on characterizing grain size and distribution in vanadium dioxide (VO2) thin films using Atomic Force Microscope (AFM) images. Traditional segmentation methods face challenges in accurately detecting grains, and this paper addresses these limitations by employing machine learning-based classification approaches, defining three classes: grains, joints or dividing lines, and the background. Various classification methods, including supervised, unsupervised, and thresholding-based approaches, were investigated, demonstrating the superiority of machine learning-based methods over traditional segmentation techniques. Deep Learning (DL) models, such as Convolutional Neural Networks (CNN), Deep Belief Networks (DBN), and Deep Boltzmann Machines (DBM), achieved the best results in accuracy and precision. The DBN algorithm, in particular, outperformed other methods with a 93.66% accuracy in grain detection. This could be attributed to its probabilistic modeling and effective handling of challenging pixels, making it a powerful tool for accurate grain size and distribution analysis.

Properties of nanostructured hematite prepared by various coating techniques for potential PEC water splitting applications

In this study, hematite (α-Fe2O3) thin films were synthesized using dip coating and spray pyrolysis techniques on fluorine-doped tin oxide substrates, and the morphological, optical, and structural properties of the hematite were studied. Six peaks were identified for both techniques from X-ray diffraction measurements. The (104) and (110) phases which are the main peaks describe the corundum structure of α-Fe2O3 while other peaks further confirm the formation of high purity α-Fe2O3. Raman spectroscopy revealed seven vibrational modes (two A1g and five Eg modes) of α-Fe2O3 were observed within the first Brillouin zone. Field emission scanning electron microscopy revealed mesoporous hematite nanospheres. The grain sizes were determined by average grain intercept and estimated as 45.8 ± 0.5 and 50.0 ± 0.5 nm respectively for films prepared by spray pyrolysis and dip-coating. Ultraviolet–visible spectroscopy results showed good absorbance for both techniques with the absorbance onset at 597 nm for dip coated films as compared to onset at 609 nm for spray pyrolysis films. From this work it was determined that coating techniques can affect the grain sizes of hematite films. This could potentially contribute to improved absorption of light for photoelectrochemical water splitting applications.