Surface Morphology Of Thin Films Research Articles

Hydrogen-assisted chemical vapor deposition for heteroepitaxial growth of pure ε-Ga2O3 films

This study presents a novel approach to control the crystalline phase and surface morphology of substable ε-Ga2O3 thin films by regulating the hydrogen flow rate during chemical vapor deposition (CVD). The objective is to achieve high-quality and cost-effective heteroepitaxial pure-phase single-crystalline ε-Ga2O3 thin films on sapphire substrates. The crystalline phases and crystalline qualities of the thin films were determined by X-ray diffraction (XRD) and Raman spectroscopy. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) results show that the surface of the ε-Ga2O3 films prepared by this method is flat and the minimum value of the surface roughness (RMS) is 4.130 nm. We explain the reason for the differences in the surface morphology of the films from the point of view of hydrogen passivation. Measurements by UV–Visible spectrophotometer, the UV cut-off edge is located at 250 nm and the optical band gap is about 4.9 eV. The experimental results show that with the increase of hydrogen flow rate, the content of β-Ga2O3 in the films and the surface roughness and maximum height of the contour (RZ) decreases, until a smooth surface of the pure-phase ε-Ga2O3 film is produced. The success of the chemical vapor deposition method for heterogeneous epitaxy of high-quality ε-Ga2O3 films on sapphire substrates greatly reduces the production cost and expensive investment in production equipment, which makes its application in high electron mobility transistors, piezoelectric resonators, and sun-blind detectors have great potential, and at the same time, this method provides ideas for the preparation of other metastable materials.

Optimization of TiN/TiOxNy Laminated Electrode Films for High-Performance Gene Sequencing Chip

With continuous advancement of the fourth generation nanopore gene sequencing technology, the requirements for performance of the electrode films in gene sequencing chips are increasing. This study utilized the high vacuum reactive magnetron sputtering method to examine the impact of working pressure on the electrical, electrochemical, crystal structure, chemical composition, and surface morphology of TiOxNy thin films in detail. The findings revealed that the TiN thin film deposited at 0.4 Pa exhibited the lowest resistivity of 391.9 μΩ·cm. Additionally, the TiOxNy thin film deposited at 1.6 Pa demonstrated the highest volumetric specific capacitance of 35.37 mF·cm−2·μm−1 at 5 mV·s−1. Utilizing the optimal parameters, TiOxNy laminated electrode thin films were in situ grown. Through measurements and analysis, it was found that the TiOxNy electrode thin film effectively achieves a 29.35% improvement in specific capacitance compared to the single layer TiOxNy electrode thin film. The integration of a TiN current collector with low resistivity effectively reduced the internal resistance of the electrode system and decreased the response time to 0.038 s. The features of low impedance and high specific capacitance of TiOxNy laminated thin films offer promising prospects for the preparation of gene sequencing chip with high throughput.

Influence of pH value of precursor on growth, structural, and optical properties of Cu2O thin films grown in Mist-CVD

The Cu2O thin films were prepared from copper (II) acetylacetonate (Cu(acac)2) by the mist chemical vapor deposition (mist-CVD) method, depending on the pH value of the prepared solution. It was confirmed that the well-oriented Cu2O thin films were grown at a dominant (111) peak according to X-ray diffraction (XRD) measurement using an alkaline precursor solution. The pH of the prepared solution drastically affected the surface morphology of the Cu2O thin films, and the lowest Root Means Square (RMS) was found for pH-10 of the precursor solution. The confocal Raman spectrum confirmed the formation of the cubic Cu2O crystal structures for each pH value of the precursor solution. The very transparent Cu2O thin films that were grown. The highest transmittance, 70%, was obtained at 1100 nm from the absorption spectrum for Sample B. The optical energy band gaps of Cu2O thin films were determined using Tauc's method and found to vary within a range of 2.53 to 2.49 eV, indicating a change in the material's electronic structure. The study demonstrated the crucial role of the pH level of the prepared solution in the growth of the Cu2O thin film. Specifically, it was found that a higher pH level resulted in a greater concentration of hydroxide ions (OH−), which was a crucial factor in the growth process. These findings can be significant in using p-type Cu2O thin films prepared based on mist-CVD for optoelectronic applications.

Surface Morphology of Thin Films of (Y0.06Ga0.94)2O3 Activated by Cr3+

Surface Morphology of Thin Films of (Y0.06Ga0.94)2O3 Activated by Cr3+

Tuning the crystalline orientation of quasi 1D anisotropic Sb2Se3 as a function of growth temperature for thin film photovoltaic applications

Antimony selenide (Sb2Se3) shows excellent photon absorption in the visible region and hence gaining tremendous attention from the last decade for thin film photovoltaics. Also, it has unique one-dimensional crystal structure and simple binary composition. However, the growth of Sb2Se3 thin films with its predominant orientation along [hk1] to make use of easy electrical charge transport seems challenging due to various governing growth parameters. In this work, we have studied the role of growth temperature (between 200 ℃ and 320 ℃) in the crystalline orientation of Sb2Se3 thin films on glass substrates via close-space thermal evaporation. In addition to growth orientation, we have investigated the effect of growth temperature on the surface morphology, elemental composition, film thickness, and optical properties of Sb2Se3 thin films. Electrical properties and photoresponse were measured on [hkl] and [hk0] oriented films to understand the effect of anisotropy and it is inferred that [hk1] oriented film as a favorable one for the charge transport. Also, the photoresponse results showed fair photoconductance under white light illumination and zero applied bias.

Improved cyclic durability and chemical stability of WO3 thin films by incorporation of Nb2O5

To achieve commercial smart windows operating in environments exposed to air and moisture with a hot weather, there has been a steady demand for large-area electrochromic thin films with high cyclic durability and chemical stability. In this article, we discuss the change in the electrochromic performance of WO3 thin films through incorporation of Nb2O5, which is stable against an acid electrolyte and heated water. With the increase in the content of Nb2O5 achieved by increasing the sputtering power, the charge density and transmittance modulation gradually decreased, while the cyclic durability was noticeably improved. When the as-deposited WO3 thin films were soaked in water at 70 °C, their flat surface and electrochromic properties degraded significantly. Conversely, the deterioration of the surface morphology of the Nb2O5-incorporated WO3 thin films after etching in the heated water was alleviated, which led to electrochromic performances on par with those of the unetched films. This is an effective approach for manufacturing of electrochromic devices with an enhanced stability to prevent structural degradation under hot and humid conditions.

Effect of heat treatment on the surface morphology and optical properties of the Al2O3 thin film for use in solar cells

Effect of heat treatment on the surface morphology and optical properties of the Al2O3 thin film for use in solar cells

Study of surface morphology of Ag thin films prepared by sputtering and irradiation with keV Ar ion beam

In this paper, the possibility of preparing silver nanostructures with a high area density of nanoparticles of various shapes by the ion beam sputtering (IBS) method, using a glancing angle deposition (GLAD) configuration, and subsequent irradiation with heavy ions, was tested. In the experiment, keV Ar+ ions were used for both IBS and bombardment. The prepared nanostructures were analyzed by RBS and microscopic methods of SEM and AFM. It turned out that IBS/GLAD makes it possible to create silver nanostructures (networks of individual silver nanoparticles), but only with relatively low areal densities (∼ 70 µm2). The bombardment led to changes in the porosity only after high ion fluences, but also to disruption of the nanostructures. Even so, the IBS method with GLAD configuration has been shown to be a promising way to prepare high-porosity nanostructures. Nevertheless, further experimental efforts will be needed to find the optimal technology.

Electrical performance of La-doped In2O3 thin-film transistors prepared using a solution method for low-voltage driving.

In this paper, La-doped In2O3 thin-film transistors (TFTs) were prepared by using a solution method, and the effects of La doping on the structure, surface morphology, optics, and performance of In2O3 thin films and TFTs were systematically investigated. The oxygen defects concentration decreased from 27.54% to 17.93% when La doping was increased to 10 mol%, and La served as a carrier suppressor, effectively passivating defects such as oxygen defects. In fact, the trap density at the dielectric/channel interface and within the active layer can be effectively reduced using this approach. With the increase of La concentration, the mobility of LaInO TFTs decreases gradually; the threshold voltage is shifted in the positive direction, and the TFT devices are operated in the enhanced mode. The TFT device achieved a subthreshold swing (SS) as low as 0.84 V dec-1, a mobility (μ) of 14.22 cm2 V-1 s-1, a threshold voltage (VTH) of 2.16 V, and a current switching ratio of Ion/Ioff of 105 at a low operating voltage of 1 V. Therefore, regulating the doping concentration of La can greatly enhance the performance of TFT devices, which promotes the application of such devices in high-performance, large-scale, and low-power electronic systems.

Study of Structural Morphology of Electrodeposited Ni Film

Structural morphology of thin electrodeposited metallic films plays a vital role in determining the properties of the films and their application. We prepared a range of Ni electrodeposited polycrystalline films using a BIOLOGIC potentiostat and investigated the effects of varying parameters such as the deposition rate and concentration of the solution to improve control over their properties. We conducted analysis of surface morphology of thin films of area 1cm2, as well as at microstructural level of area 50x50 um2, using ex-situ AFM and in-situ HS AFM. Ex-situ AFM data helps us to do quantitative surface analysis, including slope, scaling analysis [1] and grain area calculation as a function of time, concentration, and applied potential. HS AFM provides us with information about the grain structure evolution at microstructural level [2]. The texture of films was determined by XRD analysis. For the thin films, Ni[111] orientation was dominant, but for thick films, the dominant crystallographic orientations was Ni[200].We also performed EBSD analysis for Ni thin films after milling with focused ion beam. EBSD uses backscattered electron to obtain the information of structural morphology and crystallographic orientation of thin films layer by layer. The correlation between ex-situ AFM and EBSD data helps to gain a clear understanding of the structural features of the films. Liu, L., & Schwarzacher, W. (2013). Slope analysis and scaling analysis of electrodeposited thin films. Electrochemistry communications, 29, 52-54.Koorikkat, A., Payton, O., Picco, L., & Schwarzacher, W. (2020). Imaging the Surface of a Polycrystalline Electrodeposited Cu Film in Real Time Using In Situ High-Speed AFM. Journal of the Electrochemical Society, 167(16), 162510.

Experimental and theoretical analysis of a Visible-Light photodetector based on cadmium sulfide fabricated on interdigitated electrodes

The wide range of applications for photodetectors, such as in space, industry, medical, and military, has garnered significant research attention in recent years. In this study, an n-type single-layer photodetector based on a Cu/CdS/Cu metal–semiconductor-metal structure with a micro interdigitated electrode array (IDE) was fabricated. The surface morphology and absorption properties of the CdS thin films were characterized using atomic force microscopy, scanning electron microscopy, and UV–Vis spectrometry. The photo response characteristics of the photodetector were recorded across wavelengths of 400–780 nm. The optoelectronic analyses of the structure revealed a maximum responsivity value of approximately 98.73 % at 405 nm incident light, with a high response time of about 0.12 s. Furthermore, the structure was theoretically studied and simulated, with the simulation results demonstrating good agreement with the measured experimental evidence. The above results indicate that the present CdS photodetector holds excellent potential for use in high-sensitivity optoelectronic integrated circuits.

Abnormal high stability halide perovskite thin films and solar cells to alpha and gamma irradiations with varying fluence

Solar cells (SCs) and thin films made of methylammonium lead tri-iodide (MAPbI3) have demonstrated remarkable robustness when irradiated with alpha (He2+) and gamma radiations from americium-241. This study investigates changes in the structure, absorption, and surface morphology of perovskite thin films, as well as the photoelectronic properties of MAPbI3 SCs, with and without irradiation with He2+. According to the XRD analysis, tetragonal MAPbI3 showed increased crystallinity and a decrease in compression micro-strain with an increased flux of He2+. UV–Vis absorption remained unchanged until the flux exceeded 7.36 x 1012 He2+ cm−2. The bandgaps for irradiated films decreased similarly to pristine films up to a dose of 3.07 x 1012 He2+cm−2, with significant differences observed beyond this point. Digital images showed significant changes in thin films irradiated at fluences exceeding 3.07 x 1012 He2+ cm−2, with pits forming in grains responsible for the changes, confirmed by scanning electron microscopy. In conclusion, this study found that MAPbI3 thin films and SCs can withstand doses of He2+ up to 3.07 x 1012 He2+ cm−2 in a He2+ radiation environment.

Studies on physical properties of tin oxide films

This paper reports the study of some physical properties of thin films of tin oxide, such as the structural properties, surface morphology and optical transmission and reflection. The thin films of tin oxide were deposited by the method of thermal evaporation under vacuum. Transmission electron microscopy (TEM) was used to study the structural properties and the atomic force microscopy (AFM) method was used to study the surface morphology of thin films of tin oxide. The absorption and extinction coefficients of the investigated thin layers were determined from the transmittance and reflectance spectra recorded in the range of wavelengths between 190 and 1100 nm.

MBE growth of SnTe films on GaAs substrates with ZnTe buffer layers

SnTe (100) single-domain thin films have been previously grown on GaAs substrates by molecular beam epitaxy but obtaining excellent crystallinity can be difficult. In this paper, ZnTe buffer layers are introduced to improve the crystallinity of SnTe films. The effects of the molecular beam flux ratio (JTe/JSn) and growth temperature (Tg) on the crystallinity are investigated to achieve high-quality layers. The surface morphology and electrical properties of the SnTe thin films are also evaluated in addition to the conventional X-ray diffraction (XRD)measurements. The crystallographic properties of the grown samples are shown to be significantly improved by introducing a ZnTe buffer layer. XRD (θ–2θ) full width at half maximum of the lowest value obtained so far is about 0.14°. It is also found that lowering JTe/JSn to 0.6 results in a reduced growth rate, and an increased growth temperature (Tg = 220 °C) promotes the migration of atoms at the growth front. Both effects contribute to improvement in the crystallographic quality, including the layer surface smoothness. The cross-sectional transmission electron microscopy observation of the sample indicates the abrupt interface formation with different lattice structures. It is also found that low growth temperatures (below 200 °C) are not favorable for the SnTe layer growth, which is confirmed by the surface morphology.

Unveiling the multifaceted impact of C2H2 flow on SiCN CVD coatings: Mechanical mastery and beyond

This comprehensive study systematically investigates the influence of C2H2 flow rates on silicon carbonitride (SiCN) thin films deposited on p-type c-Si (100) substrates through Chemical Vapor Deposition (CVD). Across a range of C2H2 flow rates (1–15 sccm), the study quantitatively analyzes surface morphology, crystallinity and mechanical characteristics. Analyzing the data quantitatively: Surface morphologySEM and AFM analyses unveiled distinctive surface patterns influenced by varying C2H2 flow rates. Surface roughness exhibited a quantitative increase, rising from 1.2 nm at 1 sccm to 2.4 nm at 15 sccm. Ftir analysisFTIR spectroscopy identified three major vibrational signatures in SiCN thin films: Si-Hn wagging, n-SiC, and Si–C stretching. Notably, the intensity of the n-SiC peak demonstrated a quantitative rise with increasing C2H2 flow rate. XRD analysisXRD confirmed the quantitative impact of C2H2 flow rates on crystallinity. The SiCN thin film deposited at 15 sccm exhibited the highest crystallinity, with a quantified crystallite size of 15 nm. Nanoindentation testingHardness and Young's modulus were quantitatively assessed through nanoindentation testing. SiCN thin films showed a quantitative increase in both hardness and Young's modulus with rising C2H2 flow rates. The film deposited at 15 sccm demonstrated the highest hardness (i.e. 19.23 GPa) and Young's modulus (i.e. 271.56 GPa).In summary, this study establishes the significant impact of C2H2 flow rates on the quantitative aspects of surface morphology, crystallinity, and mechanical properties of SiCN thin films. Notably, the film deposited at 15 sccm emerges as distinctive, exhibiting the highest quantitative values for crystallinity, hardness and Young's modulus. This comprehensive analysis enhances the understanding of intricate relationship between C2H2 flow rates and the multifaceted properties of SiCN thin films.

Coating Corn Seeds with Silver Using DC Magnetron Plasma to Protect Them from Biological Effects

The silver was sputtered as layers on corn seeds using a direct current plasma planar magnetron sputtering. Three samples of corn seeds coated with silver resulted from varying the sputtering times 1,2, and 3 min. AFM and XRD technique were used to study the surface morphology of Ag thin films and structure properties. Cultivation of corn grains treated with the three levels of sputtering individually 1, 2 and 3 minutes did not affect the germination percentage. The atomic absorption spectrophotometer’s findings showed that the amounts of silver in plant of the control treatment (without sputtering) did not differ significantly from the spraying treatment for the three levels, where it was 0.350 ppm and for sputtering treatment at levels 1,2,3 minutes and the gum Arabic treatment were 0.363, 0.368, 0.385, 0.382 ppm respectively.

Study on the effect of sputtering pressure on the physical properties of InN films on ITO substrate and the dependence of carrier transport characteristics of Li-doped p-NiO/n-InN heterojunction on the environmental temperature

The exceptional performance of ITO substrate has made it possible to use indium nitride (InN) material in a variety of applications. The combination of lithium-doped NiO and n-type InN in a heterojunction shows great potential as a material for optoelectronic devices. This study investigates the influence of sputtering pressure on the crystal structure, surface morphology, optical properties, and electrical characteristics of InN thin films prepared on ITO substrates through magnetron sputtering. The research findings indicate that the InN films grow preferentially along the (002) crystal plane, with the best crystalline quality observed under a sputtering pressure of 1.5 Pa. Subsequently, the changes in the optical bandgap, transmittance, and reflectance of the InN films with varying sputtering pressure were discussed. The study also discusses a comprehensive analysis of the trends in the electrical characteristics of the InN films with sputtering pressure and environmental temperature, demonstrating their excellent thermal stability at high temperatures. Additionally, Li-doped p-NiO/n-InN heterojunction devices were fabricated and analyzed to determine the influence of environmental temperature on the carrier transport characteristics of the devices, revealing their favorable electrical properties at different temperatures. This research enriches the field of InN material studies and opens up new prospects for the performance and practical applications of InN optoelectronic devices.

High-Performance Thermoelectric Flexible Ag2Se-Based Films with Wave-Shaped Buckling via a Thermal Diffusion Method.

Herein, an n-type Ag2Se thermoelectric flexible thin film has been fabricated on a polyimide (PI) substrate via a novel thermal diffusion method, and the thermoelectric performance is well-optimized by adjusting the pressure and temperature of thermal diffusion. All of the Ag2Se films are beneficial to grow (013) preferred orientations, which is conducive to performing a high Seebeck coefficient. By increasing the thermal diffusion temperature, the electrical conductivity can be rationally regulated while maintaining the independence of the Seebeck coefficient, which is mainly attributed to the increased electric mobility. As a result, the fabricated Ag2Se thin film achieves a high power factor of 18.25 μW cm-1 K-2 at room temperature and a maximum value of 21.7 μW cm-1 K-2 at 393 K. Additionally, the thermal diffusion method has resulted in a wave-shaped buckling, which is further verified as a promising structure to realize a larger temperature difference by the simulation results of finite element analysis (FEA). Additionally, this unique surface morphology of the Ag2Se thin film also exhibits outstanding mechanical properties, for which the elasticity modulus is only 0.42 GPa. Finally, a flexible round-shaped module assembled with Sb2Te3 has demonstrated an output power of 166 nW at a temperature difference of 50 K. This work not only introduces a new method of preparing Ag2Se thin films but also offers a convincing strategy of optimizing the microstructure to enhance low-grade heat utilization efficiency.

Phase Composition and Surface Morphology of Thin AlN Films Obtained trough Magnetron Sputtering

Phase Composition and Surface Morphology of Thin AlN Films Obtained trough Magnetron Sputtering

Enhancing thermoelectric properties of CuNiO thin films through post-annealing: Effect on Seebeck coefficient and power generation

The need for the best thermoelectric power generation to extract low-grade heat energy from the human body has generated considerable interest. However, developing oxide-based thermoelectric materials with both high stability and Seebeck coefficient remains challenging. In this work, we have prepared CuNiO thin film with an economical and simple thermal evaporation method and post-annealed at different temperatures from 400 to 550 °C. XRD and SEM have determined the crystal structure and surface morphology of the CuNiO thin film. The electrical conductivity and charge carrier concentration increase with post-annealing temperature due to the formation of the secondary phases. The Seebeck coefficient has decreased from 65.1 to 37.9 µV/K with post-annealing temperature due to improved charge carrier density, the electronic band structure of the material and secondary phases. The maximum power factor has been achieved in the unannealed sample.