Surface Roughness Of Films Research Articles

High Optical Contrast of Quartet Dual-Band Electrochromic Device for Energy-Efficient Smart Window.

A quartet dual-band electrochromic device (ECD) was developed to selectively control the transmittance from the visible to near-infrared wavelengths for the application of an energy-efficient smart window. The new AgNO3+TBABr+LiClO4 (ATL)-based electrolyte was developed to independently control the redox reaction of lithium and silver ions to demonstrate the quartet mode of an ECD. A dual-band ECD with a sandwich structure was assembled using an ATL-based electrolyte, WO3 electrochromic layer, and antimony-doped tin oxide (ATO) ion storage layer. The employed WO3 and ATO films were fabricated using a nanoparticle deposition system (NPDS), a novel ecofriendly dry deposition method. Four modes, namely, transparent, warm, cool, and all-block modes, were demonstrated via an independent redox reaction of both lithium and silver ions through the simple control of the applied voltage. In the warm mode, the localized surface plasmon resonance effect was exploited by producing silver nanoparticles upon two-step voltage application. Furthermore, since the high surface roughness of the WO3 thin film fabricated by NPDS maximized the light scattering effect, 0% transmittance at all wavelengths was observed in the all-block mode. Dual-band ECD showed high optical contrasts of 73% and long-term durability over 1000 cycles with no degradation. Therefore, the possibility of controlling transmittance at the target wavelength was confirmed using a simple device with a simple process, suggesting a new strategy for the design of dual-band smart windows to reduce the energy consumption of buildings.

Solution-Processed High Performance Ytterbium-Doped In2O3 Thin Film Transistor and Its Application in Common-Source Amplifier

In this article, we investigated Ytterbium (Yb)-doped Indium-oxide (In2O3)-based thin-film transistor (TFT) prepared by the solution-processed. Indium-Yb-oxide (InYbO) films with different Yb-doping concentrations were prepared by the solution-processed to reveal the variation of physical properties of In2O3 films with the changing of Yb-doping concentration. The results show that Yb-doping can improve the microstructure and surface roughness of In2O3 films and suppress the oxygen vacancy defects. When the Yb-doping concentration reaches 1 mol%, the InYbO-TFT exhibits optimal electrical performance. In addition, the performance of InYbO-TFT under positive bias stability (PBS) test is also significantly improved. The device with 1 mol% Yb concentration shows a voltage shift of 1.27 V after 3600 s of +20 V bias test, which is about <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5\times $ </tex-math></inline-formula> stable than the In2O3-TFT. Eventually, based on this InYbO-TFT, a common-source amplifier was designed. This amplifier has a 16.03 dB Gain and a cut-off frequency of 470 Hz with excellent response speed, which shows great application potential.

전자빔 표면조사에 따른 ZnO/Ag/ZnO 박막의 전기광학적 완성도 연구

Transparent ZnO/Ag/ZnO tri-layered films were deposited on a glass substrate using radio frequency and direct current magnetron sputtering. The thicknesses of the ZnO and Ag films were maintained at 30 and 10 nm, respectively, to consider the effects of electron irradiation on the optoelectrical properties of the films. XRD spectra revealed that post-deposition electron irradiated films exhibited characteristic peaks of ZnO (002) and Ag (111), respectively. The observed grain sizes of ZnO (002) and Ag (111) increased to 7.1 and 8.4 nm, respectively, under an irradiation condition of 900 eV, and the surface roughness of the electron irradiated films at 900 eV was reduced to 1.29 nm. The as-deposited films showed a figure of merit, indicating the optoelectrical performance of the films, of 4.1×10SUP-3/SUP ΩSUP-1/SUP, whereas the films electron irradiated at 900 eV showed a higher figure of merit of 1.1×10SUP-2/SUP ΩSUP-1/SUP.

A Study of Al2O3/MgO Composite Films Deposited by FCVA for Thin-Film Encapsulation.

Al2O3 and MgO composite (Al2O3/MgO) films were rapidly deposited at low temperatures using filtered cathode vacuum arc (FCVA) technology, aiming to achieve good barrier properties for flexible organic light emitting diodes (OLED) thin-film encapsulation (TFE). As the thickness of the MgO layer decreases, the degree of crystallinity decreases gradually. The 3:2 Al2O3:MgO layer alternation type has the best water vapor shielding performance, and the water vapor transmittance (WVTR) is 3.26 × 10-4 g·m-2·day-1 at 85 °C and 85% R.H, which is about 1/3 of that of a single layer of Al2O3 film. Under the action of ion deposition, too many layers will cause internal defects in the film, resulting in decreased shielding ability. The surface roughness of the composite film is very low, which is about 0.3-0.5 nm depending on its structure. In addition, the visible light transmittance of the composite film is lower than that of a single film and increases with the increase in the number of layers.

Surface activated bonding of ALD Al2O3 films

Room temperature direct bonding of plasma enhanced ALD Al2O3 films was achieved by using surface activated bonding. ALD Al2O3 films were amorphous with C and O impurities contained. The high deposition power and H2 plasma post-treatment increased the crystallinity and hydrophilicity of ALD Al2O3 films, respectively. However, both methods increased the surface roughness of films slightly. The bond strength of ALD Al2O3 films was not changed obviously by raising the deposition power, but it experienced a slight decrease after H2 plasma post-treatment. The water in the debonding atmosphere influenced the bond strength of standard ALD Al2O3 films greatly, which was 0.54 J m−2 in humid air and 1.00 J m−2 in anhydrous N2. The bond strength in vacuum was just a little larger than that in anhydrous N2 suggesting that the trapped water at the bonding interface was less.

A sight of view on electrical impacts, structural properties and surface roughness of tungsten trioxide thin film: effect of substrate temperatures in WO3/Si device fabrication

Monoclinic WO3 thin films have been effectively deposited by a simple spray pyrolysis technique at a molar concentration of 0.01 M on a glass substrate in the temperature range of 473 to 673 K. These WO3 films were used as an interlayer between the metal and the semiconductor, which formed the basic structure of the photodetector. Effect of substrate temperature on WO3 films during the process of the deposition was systematically interpreted with respect to the structural, morphological, optical and electrical properties of the WO3 films. The x-ray diffraction pattern revealed the polycrystalline nature of the prepared films with monoclinic phases. At the substrate temperature of 623 K, the nano-thin films were strongly bonded to each other as observed from the FE-SEM images. Visible and ultraviolet spectroscopies indicated the band gap (Eg) of the WO3 thin film is 3.30 eV. The dc electrical study recorded a sharp increase in the electrical conductivity of the prepared film at substrate temperature of 623 K for tungsten trioxide. It is worth noting that all diodes showed a positive photoresponse under illumination. In particular, the photodetector with the thickness of 300 nm showed higher responsivity 0.02 A/W and detection specificity 8.29 × 1010 Jones.

Plasma enhanced atomic layer deposition of crystallized gallium phosphide on Si with tri-Ethylgallium and tri-tert-Butylphosphine

25 ∼ 30 nm thick polycrystalline gallium phosphide (GaP) films with high P / Ga atomic ratios were deposited on Si (100) using a plasma enhanced atomic layer deposition (PE-ALD) process with triethyl gallium (TEG), tri-tertiary butyl phosphide (tri-TBP), and atomic hydrogen. The key is chemical functionalization of the Si (100) surface since the wet-cleaned Si surface is nearly inert to TEG and tri-TBP. In-situ Auger spectroscopy was employed to identify the most successful functionalization which employed a gas phase mixture of atomic hydrogen and tri-TBP consistent with formation of a surface phosphide layer on Si(100); this layer efficiently nucleated the PE-ALD of GaP. The crystallinity and surface roughness of GaP films were tuned by controlling the pulse length of atomic H plasma, showing the self-limiting ALD film growth with 2.7 Å/cycle. The optimal crystallized GaP thin film on 6°-miscut Si showed local epitaxy growth of homogeneous GaP epi-layers in transmission electron microscopy (TEM).

Process optimization and effect of sputtering pressure on electrochromic properties of flexible WO3 films prepared by DC magnetron sputtering

In this study, WO3 films were prepared on flexible indium tin oxide/polyethylene terephthalate substrates through DC magnetron sputtering at approximately 40 °C, and the process parameters were optimized. The effects of the sputtering pressure on the microstructure, morphology, and electrochromic properties of the films were investigated using Raman spectroscopy, scanning electron microscopy, x-ray diffraction, atomic force microscopy, and electrochemical techniques. The results showed that the thickness, surface roughness, and grain size of the WO3 films changed with increasing pressure, and the optimal values of these parameters for excellent electrochromic properties of the WO3 films were 731, 53.5, and 1.79 nm, respectively, at 2.0 Pa. The optical modulation amplitude reached 84.66% at 455 nm, and the coloring and bleaching response times were 7.64 s and 6.76 s, respectively. The electrochemical impedance spectroscopy results showed that the films prepared at 2.0 Pa had the smallest Rct (41.63 Ω).

Cathodic arc deposition of high entropy alloy thin films with controllable microstructure

High entropy alloys (HEAs) are a novel class of materials exhibiting properties of high strength, high corrosion and oxidation resistance, and superb thermal stability. Cathodic arc deposition is an established physical vapor deposition (PVD) technology offering high deposition rate and high degrees of plasma ionization with controllable ion kinetic energy. Here we employed cathodic arc deposition to fabricate AlCrFeCoNiCu0.5 HEA thin films. To elucidate the growth mechanisms and microstructures of the HEA thin film microstructures, we varied arc and duct currents. The crystallography of the films was investigated using X-ray diffraction (XRD). The film chemistry and microstructure of the film-substrate interphase were comprehensively studied using transmission electron microscopy (TEM). Atomic force microscopy (AFM) was applied to study the surface morphology, and mechanical properties were evaluated using nanoindentation. It is demonstrated that the grain size in HEA thin films can be effectively controlled by the deposition rate, while the HEA film hardness and surface roughness are modulated by the grain size. The results presented here have important implications for the fabrication of HEA thin films using cathodic arc deposition as an industrially scalable technique.

Optical and Electrophysical Properties of Vinylidene Fluoride/Hexafluoropropylene Ferroelectric Copolymer Films: Effect of Doping with Porphyrin Derivatives.

Polymer films doped by different porphyrins, obtained by crystallization from the acetone solutions, differ in absorption and fluorescence spectra, which we attribute to the differences in the structuring and composition of the rotational isomers in the polymer chains. According to the infrared spectroscopy data, the crystallization of the films doped with tetraphenylporphyrin (TPP) proceeds in a mixture of α- and γ-phases with TGTG- and T3GT3G- conformations, respectively. Three bonds in the planar zigzag conformation ensures the contact of such segments with the active groups of the porphyrin macrocycle, significantly changing its electronic state. Structuring of the films in the presence of TPP leads to an increase in the low-voltage AC-conductivity and the registration of an intense Maxwell-Wagner polarization. An increased conductivity by an order of magnitude in TPP-doped films was also observed at high-voltage polarization. The introduction of TPP during the film formation promotes the displacement of the chemical attachment defects of "head-to-head" type in the monomeric units into the surface. This process is accompanied by a significant increase in the film surface roughness, which was registered by piezo-force microscopy. The latter method also revealed the appearance of hysteresis phenomena during the local piezoelectric coefficient d33 measurements.

Epitaxial growth of β-Ga2O3 thin films on SrTiO3 (1 1 1) and (1 0 0) substrates by chemical vapor deposition

Due to good lattice matching and bipolar doping behavior, wide bandgap SrTiO3 (STO) is a promising substrate for the heteroepitaxial growth of β-Ga2O3 to construct heterojunctions for (opto-)electronic device applications. However, the investigation of the growth of β-Ga2O3 film on the STO (111) substrate is still lacking. In this work, for the first time, the β-Ga2O3 (2¯ 01) thin films were epitaxially grown on the supercell matched STO (111) substrates by low pressure chemical vapor deposition. The effects of the source and growth temperatures on the surface roughness and crystalline quality of the β-Ga2O3 films were systemically investigated. By controlling the supply of Ga source, the heteroepitaxial β-Ga2O3 film grown under the optimized conditions exhibits a narrow X-ray diffraction rocking curve of 0.75° and a low root-mean-square roughness of 1.10 nm. Furthermore, the epitaxial growth of β-Ga2O3 films on the STO (100) substrate was also investigated. The heteroepitaxy of β-Ga2O3 films on STO lays the foundation for future device applications of β-Ga2O3-based heterojunctions.

Release kinetics of pectin/eugenol composite film and application in pork preservation

AbstractBiodegradable active packaging materials have received growing attention for extending the shelf life of foodstuffs. A Pectin/eugenol (Pe/Eu) composite film is prepared by casting from pectin and eugenol. The morphology and wettability of the composite film are characterized. The antioxidant activity of the composite film is determined with DPPH method. Special attention is given to the release kinetics of Eu from Pe/Eu composite film and its application in pork preservation. The results display that Eu increased the surface roughness, hydrophobicity, and antioxidant activity of the composite film. In addition, the release mechanism of Eu from Pe/Eu composite film is controlled by diffusion. The release behavior of Eu in Pe/Eu composite film can prolong the shelf life of pork. Therefore, our results suggest that Pe/Eu composite films can provide new ways for active packaging materials to extend the shelf life of animal‐based protein foods.

Heteroacene-Based Polymer with Fast-Switching Visible-Near Infrared Electrochromic Behavior.

The electrochromic properties and application of electronically conducting polymers (ECPs) (PTRPZ-EDOT) consisting of a 3,4-ethylenedioxythiophene (EDOT) and the heteroacene-based molecular scaffold, 6H-pyrrolo[3,2-b:4,5-b'] bis [1,4] benzothiazine (TRPZ), are reported. Known for its high electron mobility and conducting properties, the novel TRPZ scaffold was synthesized to possess two EDOT molecules termini affording TRPZ-EDOT. Electropolymerization of TRPZ-EDOT resulted in remarkable spectroscopic and conductive properties suitable for electrochromic device fabrication. Using atomic force microscopy (AFM), the average surface roughness and surface topography of PTRPZ-EDOT polymer thin films were determined. Spectroelectrochemical data showed that the polymer achieved switching times of 4.07 (coloration) and 0.47 s (bleaching) at 539 nm. The PTRPZ-EDOT film exhibits an optical contrast of 36-44% at 539 nm between its neutral and colored states, respectively. The NIR region from 1000 to 1700 nm shows the appearance of charge carrier bands with a 0-1 V potential range. An electrochromic device was successfully fabricated from PTRPZ-EDOT, showcasing the potential and applicability of the polymer material for advanced technologies such as smart windows, flexible electrochromic screens, and energy storage devices.

Influence of Al and Cu Doping on the Structure, Morphology, and Optical Properties of ZnO Thin Film

In this study, ZnO thin films doped with Al (AZO) and Cu (CZO) were fabricated on a glass substrate via sol-gel spin coating. The influence of 1 atomic % Al and Cu doping on the structure, morphology, as well as optical properties of ZnO thin film was then analyzed with X-ray diffraction (XRD), atomic force microscopy (AFM), and UV-Vis spectroscopy. XRD analysis revealed that all samples possessed hexagonal wurtzite crystal structures with 3 to 4 preferred orientations. Al and Cu doping caused a decrease in crystal size, while the lattice strain (e) and dislocation density (ρ) were increased. AFM indicated that Al and Cu doping reduced the surface roughness of the ZnO thin film. Optical measurement showed that all samples exhibited high transmittance (&gt; 80%) in the visible light region. Transmittance was reduced after doping, while the band gaps for ZnO, AZO, and CZO thin films are 3.26, 3.28, and 3.23 eV. This study showed that an addition of 1 atomic % transition metal (Al and Cu) greatly influences the structure, morphology, and optical properties of ZnO thin film.

Characterization of Structure, Morphology, Optical and Electrical Properties of AlN–Al–V Multilayer Thin Films Fabricated by Reactive DC Magnetron Sputtering

Composite thin films of the AlN–Al–V type, grown by magnetron sputtering, were analyzed by several complementary diagnostic methods. The power of the magnetron was used as a variable parameter, while gas flows, chamber pressure, and substrate temperature remained unchanged during the film fabrication. According to grazing incidence X-ray diffraction (GIXRD) results, in most cases, it was possible to obtain an (002)-oriented aluminum nitride (AlN) layer in the films, although, with an increase in the magnetron power to 800 W, the formation of X-ray amorphous AlN was observed. Similarly, according to the Raman results, the width of the peak of the vibrational mode E1, which characterizes the correlation length of optical phonons, also significantly increased in the case of the sample obtained at 800 W, which may indicate a deterioration in the crystallinity of the film. A study of the surface morphology by atomic force microscopy (AFM) and scanning electron microscopy (SEM) showed that the AlN film grows in the form of vertically oriented hexagons, and crystallites emerge on the surface in the form of dendritic structures. During the analysis of the AFM roughness power spectral density (PSD-x) functions, it was found that the type of substrate material does not significantly affect the surface roughness of the AlN films. According to the energy–dispersive X-ray spectroscopy (SEM-EDS) elemental analysis, an excess of aluminum was observed in all fabricated samples. The study of the current-voltage characteristics of the films showed that the resistance of aluminum nitride layers in such composites correlates with both the aluminum content and the structural imperfection of crystallites.

Antibacterial efficiency of cadmium thin films deposited by the thermionic vacuum arc

In this study, thin films of the pure Cadmium (Cd) were deposited on glass and high-density polyethylene (HDPE) samples by the Thermionic Vacuum Arc (TVA) method. The structural and surface morphological properties of Cd thin-films were investigated using X-ray diffraction patterns (XRD), field emission scanning electron microscope (FE-SEM), and atomic force electron microscope (AFM). The water contact angle (WCA) was determined by a Krüss DSA100 model goniometer. The antibacterial activities of the Cd-coated and uncoated samples were investigated by direct-contact test and modified Kirby-Bauer test against Escherichia coli O157:H7 ATCC35150, Staphylococcus aureus ATCC6538P and Listeria innocua ATCC33090. Cd thin films deposited on both samples were found to be in crystalline form. The Crystallite size of the films deposited on glass and HDPE were calculated as 52.1 and 72.5 nm, respectively. The SEM and AFM depict the Cd films uniform distribution of grains. The root mean square (Rms) surface roughness of Cd thin film was found as 39.3 nm and 70.3 nm on glass and HDPE substrates, respectively. The WCA measurements showed the cadmium coatings increased the hydrophobicity of glass and HDPE samples. Direct-contact test showed both Cd-coated samples totally inhibited E. coli O157:H7 and L. innocua strains after 2-h of contact time. Modified Kirby-Bauer test indicated the Cd-coated HDPE samples showed the highest antibacterial activity against L. innocua however Cd films did not have any antibacterial activity for both samples against S. aureus.

TD-DFT calculations and optical properties of a luminescent thiazolopyrimidine compound with different emission colors and uncommon blue shift upon aggregation

A thin film of 7-oxo-thiazolopyrimidine-3,8-dicarbonitrile derivative [7-ThPyDi]TF was prepared using a spin coating technique. The surface morphology and molecular structure are studied using various techniques such as XRD, FTIR, and scanning electron microscope (SEM). Moreover, the quantum chemical calculations were carried out through time-dependent density functional theory (TD-DFT) to investigate some reactivity descriptors such as softness and electronegativity. Also, Au/[7-ThPyDi]TF/p-Si/Al heterojunction diodes were fabricated. It was revealed that the energy bandgap value of [7-ThPyDi] as an organic thin film is 3.58 eV for direct transitions and 3.94 eV for indirect transitions, respectively, and this value falls within the semiconductor material range. The atomic force microscope demonstrated that the surface roughness of the thin film is approximately 32.2 nm. Because of its high refractive index, this material has the potential application as an antireflection coating for solar cells and as lenses with a wide focal range. We investigated a blue luminescent thiazolopyrimidine compound; the maximum emission in the more aggregated state (higher solution concentration) exhibits a notable blue shift compared to the more diluted solution. This uncommon phenomenon has been understood by structural analyses using density functional theory. The chemical structure of the molecule [planar conjugated cores and strong polar groups (–CO and –CN)] enables it to interact with both itself and the polar solvent. The intermolecular interactions result in the bending of the conjugated plane. As a result, the blue shift happens upon aggregation when the conjugated effect becomes weaker. The studied molecule gave different emission colors (blue, yellow, and reddish green) depending on the molecular packing.

Dragon Fruit Peel Extract Enriched-Biocomposite Wrapping Film: Characterization and Application on Coconut Milk Candy.

Bio-based film is an eco-friendly alternative to petroleum-based packaging film. The effects of biocomposite wrapping film enhanced with dragon fruit peel extract (0, 2% w/v, respectively) and currently used commercial packaging film (polypropylene; PP) on coconut milk caramels during storage (30 °C, 75% RH, nine days) were studied. Both 0% and 2% DPE-enriched biocomposite films were thicker and had higher water vapor permeability and solubility than the PP film but poorer mechanical characteristics. In addition, the 2% film possessed antioxidants and antioxidant ability. A FESEM micrograph revealed the rough surface and porous path of the biocomposite films. Over the storage time, the moisture content, water activity, and springiness of the coconut milk caramel candy wrapped in the PP and all DPE-enriched biocomposite films were not significantly altered. However, the lipid oxidation as the thiobarbituric acid reactive substance (TBARS) and hardness of all coconut caramels were significantly (p < 0.05) increased during storage. Furthermore, the hardness of coconut candy covered in the control (0% DPE) biocomposite film was more pronounced on day nine of storage. However, the changes in quality characteristics of the coconut candy wrapped in each film type need to be better established. The investigating factors influencing the quality deterioration of coconut milk candy should be further identified to mitigate their effects and extend the shelf-life of the coconut candy.

Electrochemically Deposited CZTSSe Thin Films for Monolithic Perovskite Tandem Solar Cells with Efficiencies Over 17%

In spite of the high potential economic feasibility of the tandem solar cells consisting of the halide perovskite and the kesterite Cu2ZnSn(S,Se)4 (CZTSSe), they have rarely been demonstrated due to the difficulty in implementing solution‐processed perovskite top cell on the rough surface of the bottom cells. Here, we firstly demonstrate an efficient monolithic two‐terminal perovskite/CZTSSe tandem solar cell by significantly reducing the surface roughness of the electrochemically deposited CZTSSe bottom cell. The surface roughness (Rrms) of the CZTSSe thin film could be reduced from 424 to 86 nm by using the potentiostatic mode rather than using the conventional galvanostatic mode, which can be further reduced to 22 nm after the subsequent ion‐milling process. The perovskite top cell with a bandgap of 1.65 eV could be prepared using a solution process on the flattened CZTSSe bottom cell, resulting in the efficient perovskite/CZTSSe tandem solar cells. After the current matching between two subcells involving the thickness control of the perovskite layer, the best performing tandem device exhibited a high conversion efficiency of 17.5% without the hysteresis effect.

Efficient Quantum-Dot Light-Emitting Diodes Based on Solvent-Annealed SnO2 Electron-Transport Layers

Due to the sensitivity of ZnO nanoparticles to water and oxygen, the hybrid quantum-dot light-emitting devices (QLEDs) based on ZnO electron-transport layers (ETLs) suffer from shelf stability and uncontrollable positive aging problems. Tin oxide (SnO2) is considered as an ideal alternative to ZnO as the ETL in QLEDs to improve their shelf stability. Currently, the SnO2-based device still suffers from poor efficiency. Herein solvent vapor annealing (SVA) is employed to reduce the roughness of SnO2 nanoparticle films, which suppresses the leakage current and enhances the device performance. Compared with the device with pristine SnO2, the maximum brightness and current efficiency (10.8 cd/A) of QLEDs based on solvent vapor annealed SnO2 are enhanced by 25.3% and 36.6%, respectively, being comparable to the ZnO device (11.0 cd/A). Moreover, SVA processing also has a positive effect on the device shelf stability, which is attributed to the dense interface between SnO2 and quantum dots due to the reduced surface roughness of SnO2 films.