Search Results (227)

The Al-Sb co-doped SnO₂ composite thin films were prepared by the sol–gel spin-coating method. The structure, morphology, optical and electrical properties of the samples were investigated using XRD, XPS, SEM, UV-Vis spectroscopy, and Hall effect tester, respectively. It was found that when the aluminum doping amount was 15 at%, the resistivity of the sample was the lowest, and the overall optoelectronic performance was the best. Moreover, the Al-SnO₂ composite thin film transformed from an n-type semiconductor to a p-type semiconductor. When Al and Sb were co-doped, the carrier concentration increased significantly from 4.234 × 10¹⁹ to 6.455 × 10²⁰. Finally, the conduction type of the Al-Sb-SnO₂ composite thin film changed from p-type to n-type. In terms of optical performance, the transmittance of the Al-Sb co-doped SnO₂ composite thin films in the visible light region was significantly improved, reaching up to 80% on average, which is favorable for applications in transparent optoelectronic devices. Additionally, the absorption edge of the thin films exhibited a blue-shift after co-doping, indicating an increase in the bandgap energy, which can be exploited to tune the light-absorption properties of the thin films for specific photonic applications. Full article

The rising demand for sustainable energy solutions has spurred the development of advanced materials for photovoltaic devices. Among these, transparent conductive oxides (TCOs) play a pivotal role in enhancing device efficiency, particularly in silicon-based solar cells. However, the reliance on indium-based TCOs like ITO raises concerns over cost and material scarcity, prompting the search for more abundant and scalable alternatives. This study focuses on the fabrication and characterization of aluminum-doped zinc oxide (ZnO:Al, AZO) thin films deposited via Atomic Layer Deposition (ALD), targeting their application as transparent conductive oxides in silicon solar cells. The ZnO:Al thin films were synthesized by alternating supercycles of ZnO and Al₂O₃ depositions at 225 °C, allowing precise control of composition and thickness. Structural, optical, and electrical properties were assessed using Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS), Transmission Electron Microscopy (TEM), Raman spectroscopy, spectroscopic ellipsometry, and four-point probe measurements. The results confirmed the formation of uniform, crack-free ZnO:Al thin films with a spinel-type ZnAl₂O₄ crystalline structure. Optical analyses revealed high transparency (more than 80%) and tunable refractive indices (1.64 ÷ 1.74); the energy band gap was 2.6 ÷ 3.07 eV, while electrical measurements demonstrated low sheet resistance values, reaching 85 Ω/□ for thicker films. This combination of optical and electrical properties underscores the potential of ALD-grown AZO thin films to meet the stringent demands of next-generation photovoltaics. Integration of Zn:Al thin films into silicon solar cells led to an optimized photovoltaic performance, with the best cell achieving a short-circuit current density of 36.0 mA/cm² and a power conversion efficiency of 15.3%. Overall, this work highlights the technological relevance of ZnO:Al thin films as a sustainable and cost-effective alternative to conventional TCOs, offering pathways toward more accessible and efficient solar energy solutions. Full article

To meet the stringent demands of next-generation flexible optoelectronic devices, a novel fabrication approach is employed that integrates the spray-coating of copper nanowires (Cu NWs) with the magnetron sputtering of SrTiO₃ thin films, thereby yielding SrTiO₃/Cu NWs/SrTiO₃ hybrid thin films. The incorporation of the SrTiO₃ layers results in improved optical performance, with the transmittance of the Cu NW network increasing from 83.5% to 84.2% and a concurrent reduction in sheet resistance from 16.9 Ω/sq to 14.5 Ω/sq. Moreover, after subjecting the hybrid thin films to 100 repeated tape-peeling tests and 2000 bending cycles with a bending radius of 5.0 mm, the resistance remains essentially unchanged, which underscores the films’ exceptional mechanical flexibility and robust adhesion. Additionally, the hybrid thin films are subjected to rigorous high-temperature, high-humidity, and oxidative conditions, where the resistance exhibits outstanding stability. These results substantiate the potential of the SrTiO₃/Cu NWs/SrTiO₃ hybrid thin films for integration into flexible and wearable electronic devices, delivering enhanced optoelectronic performance and long-term reliability under demanding conditions. Full article

The study explores the optical and transport properties of polycrystalline ZnO thin films prepared using reactive pulsed mid-frequency sputtering with RF electron cyclotron wave resonance (ECWR) plasma. This deposition method increases the ionization degree of sputtered particles, the dissociation of reactive gas and the plasma density of pulsed reactive magnetron plasma. Optical absorption spectra reveal a sharp Urbach edge, indicating low valence band disorder. Lattice disorder and deep defect concentration are more likely to occur in samples with higher roughness. PL analysis at low temperature reveals in all samples a relatively slow (μs) red emission band related to deep bulk defects. The fast (sub-ns), surface-related blue PL band was observed in some samples. Blue PL disappeared after annealing in air at 500 °C. Room temperature Hall effect measurements confirm n-type conductivity, though with relatively low mobility, suggesting defect-related scattering. Persistent photoconductivity was observed under UV illumination, indicating deep trap states affecting charge transport. These results highlight the impact of deposition and post-treatment on polycrystalline ZnO thin films, offering insights into optimizing their performance for optoelectronic applications, such as UV detectors and transparent conductive oxides. Full article

Chemical vapor deposition (CVD) is a highly adaptable manufacturing technique used to fabricate high-quality thin films, making it essential across numerous industries. As materials fabrication processes progress, CVD has advanced to enable the precise deposition of both inorganic 2D materials, such as graphene and transition metal dichalcogenides, and high-quality polymeric thin films, offering excellent conformality and precise nanostructure control on a wide range of substrates. Conjugated conducting polymers have emerged as promising materials for next-generation electronic, optoelectronic, and energy storage devices due to their unique combination of electrical conductivity, optical transparency, ionic transport, and mechanical flexibility. Oxidative CVD (oCVD) involves the spontaneous reaction of oxidant and monomer vapors upon their adsorption onto the substrate surface, resulting in step-growth polymerization that commonly produces conducting or semiconducting polymer thin films. oCVD has gained significant attention for its ability to fabricate conjugated conducting polymers under vacuum conditions, allowing precise control over film thickness, doping levels, and nanostructure engineering. The low to moderate deposition temperature in the oCVD method enables the direct integration of conducting and semiconducting polymer thin films onto thermally sensitive substrates, including plants, paper, textiles, membranes, carbon fibers, and graphene. This review explores the fundamentals of the CVD process and vacuum-based manufacturing, while also highlighting recent advancements in the oCVD method for the fabrication of conjugated conducting and semiconducting polymer thin films. Full article

Crack-templated thin films, inspired by naturally occurring patterns such as leaf venation, spider webs, and the networked structure of dried egg white, represent a paradigm shift in the design of functional materials. Traditionally, cracks in coatings are seen as defects to be avoided due to their potential to compromise mechanical integrity and performance. However, in this context, cracks are deliberately induced and meticulously controlled to serve as templates for versatile applications. This review explores the latest advances in preparation techniques, including solvent evaporation and thermal stress induction, with a focus on the interplay between material properties (e.g., polymers and ceramics) and process parameters (e.g., drying rates and temperature, layer thickness, substrate interactions) that govern crack behavior. The resulting crack patterns offer tunable features, such as density, width, shape, and orientation, which can be harnessed for applications in semitransparent electrodes, flexible sensors, and wearable and energy storage devices. Our study aims to navigate the advancements in crack engineering in the last 10 years and underscores its importance as a purposeful and versatile strategy for next-generation thin-film technologies, offering a novel and affordable approach to transforming perceived defects into assets for cutting-edge thin-film technologies. Full article

Transparent conductive oxides are essential materials for many optoelectronic applications. For new devices for aerospace and space applications, it is crucial to know how they respond to the space environment. The most important issue in commonly used low-Earth orbits is proton radiation. This study examines the effects of high-energy proton irradiation (226.5 MeV) on thin films of aluminium-doped zinc oxide (AZO) and indium tin oxide (ITO). We use X-ray diffraction and electron microscopy observations to see the changes in the structure and microstructure of the films. The optical properties and homogeneity of the materials are determined by spectrophotometry and spectroscopic ellipsometry (SE). Analysis of the chemical states of the elements with X-ray photoelectron spectroscopy (XPS) gives insight into what proton irradiation changes at the surface of the oxides. All measurements show that ITO is less influenced than AZO. The proton energy and fluence used in this study simulate about a hundred years in low Earth orbit. This research demonstrates that both transparent conductive oxide thin films can function under simulated space conditions, with ITO showing superior resilience. The ITO film was more homogenous in terms of the total thickness measured with SE, had fewer defects and adsorbates present on the surface, as XPS analysis proved, and did not show a difference after irradiation regarding its optical properties, transmission, refractive index, or extinction coefficient. Full article

The increasing demand for advanced transparent and flexible display technologies has led to significant research in thin-film transistors (TFTs) with high mobility, transparency, and mechanical robustness. In this study, we fabricated all-transparent TFTs (AT-TFTs) utilizing amorphous indium-zinc-tin-oxide (a-IZTO) as a dual-functional material for both the channel layer and transparent conductive electrodes (TCEs). The a-IZTO was deposited using radio-frequency magnetron sputtering, with its composition adjusted for both channel and electrode functionality. XRD analysis confirmed the amorphous nature of the a-IZTO layers, ensuring structural stability post-thermal annealing. The a-IZTO TCEs demonstrated high optical transparency (89.57% in the visible range) and excellent flexibility, maintaining a low sheet resistance with minimal degradation even after 100,000 bending cycles. The fabricated AT-TFTs exhibit superior field-effect mobility (30.12 cm²/V·s), an on/off current ratio exceeding 10⁸, and a subthreshold swing of 0.36 V/dec. The AT-TFT device demonstrated a minimum transmittance of 75.46% in the visible light range, confirming its suitability for next-generation flexible and transparent displays. Full article

This study offers a comprehensive summary of the current states as well as potential future directions of transparent conducting oxides (TCOs), particularly tin-doped indium oxide (ITO), the most readily accessible TCO on the market. Solar cells, flat panel displays (FPDs), liquid crystal displays (LCDs), antireflection (AR) coatings for airbus windows, photovoltaic and optoelectronic devices, transparent p–n junction diodes, etc. are a few of the best uses for this material. Other conductive metals that show a lot of promise as substitutes for traditional conductive materials include copper, zinc oxide, aluminum, silver, gold, and tin. These metals are also utilized in AR coatings. The optimal deposition techniques for creating ITO films under the current conditions have been determined to be DC (direct current) and RF (radio frequency) MS (magnetron sputtering) deposition, both with and without the introduction of Ar gas. When producing most types of AR coatings, it is necessary to obtain thicknesses of at least 100 nm and minimum resistivities on the order of 10⁻⁴ Ω cm. For AR coatings, issues related to less-conductive materials than ITO have been considered. Full article

This work investigates the endurance and performance of aluminum-doped zinc oxide (AZO) thin films fabricated on flexible polyethylene terephthalate (PET) substrates, providing new insights into their degradation linked to mechanical flexing and accelerated thermal cycling (ATC). The current study uniquely combines cyclic bending fatigue at 23 °C and 70 °C with ATC between 0 °C and 100 °C, simulating operational stresses in real-world environments, in contrast to previous research that has focused primarily on either isolated mechanical or thermal effects. The 425 nm thick films showed high transparency and conductivity, making them suitable materials for flexible electronics and optoelectronic devices. In this work, electrical resistivity, one of the most important performance parameters, was investigated after each mechanical or thermal cycle. The results indicate that mechanical cycling at high temperatures can drastically enhance the crack formation and electrical degradation, with an over 250% change in the electrical resistance (PCER) after 12,000 cycles at 70 °C and more than 300% after 500 thermal cycles. The highly deleterious effects of combined stressors on the structural integrity and electrical properties of AZO films are underlined by these observations. This study further suggests that the design of more robust AZO-based materials/coatings would contribute toward achieving better durability in flexible electronic applications. These findings also go hand in glove with the ninth goal of the United Nations’ Sustainable Development Goals, specifically Target 9.5: Enhance Research and Upgrade Industrial Technologies. Full article

This research, which involved a comprehensive methodology, including depositing electroplated copper on a copper seed layer and Al-doped ZnO (AZO) thin films on textured silicon substrates using DC magnetron sputtering with varying substrate heating, has yielded significant findings. The study thoroughly investigated the effects of substrate temperature (Ts) on copper adhesion strength and morphology using the peel force test and electron microscopy. The peel force test was conducted at angles of 90°, 135°, and 180°. The average adhesion strength was about 0.2 N/mm for the samples without substrate heating. For the samples with substrate heating at 100 °C, the average peeling force of the electroplated copper film was about 1 N/mm. The average peeling force increased to 1.5 N/mm as the substrate heating temperature increased to 200 °C. The surface roughness increases as the annealing temperature of the Cu/AZO/Si sample increases. These findings not only provide a reliable and robust method for applying AZO transparent conductive films onto silicon solar cells but also underscore its potential to significantly enhance the efficiency and durability of solar cells significantly, thereby instilling confidence in the field of solar cell technology. Full article

Niobium oxide thin films were grown on both rigid and flexible substrates using DC magnetron sputtering for electrochromic applications. Three experimental series were conducted, varying the oxygen to argon flow rate ratio and deposition time. In the first series, the oxygen to argon ratio was adjusted from 0 to 0.32 while maintaining a constant growth time of 30 min. For the second and third series, the oxygen to argon ratios were fixed at 0.40 and 0.56, respectively, with deposition times ranging from 15 to 60 min. A structural transition from crystalline to amorphous was observed at an oxygen to argon flow rate ratio of 0.32. This transition coincided with a change in appearance, from non-transparent with metallic-like electrical conductivity to transparent with dielectric behavior. The transparent niobium oxide films exhibited thicknesses between 51 nm and 198 nm, with a compact, dense, and featureless morphology, as evidenced by both top-view and cross-sectional images. Films deposited on flexible indium tin oxide (ITO)-coated polyethylene terephthalate (PET) substrates displayed a maximum surface roughness (Sq) of 9 nm and a maximum optical transmission of 83% in the visible range. The electrochromic response of niobium oxide thin films on ITO-coated PET substrates demonstrated a maximum coloration efficiency of 30 cm² C⁻¹ and a reversibility of 96%. Mechanical performance was assessed through bending tests. The ITO-coated PET substrate exhibited a critical bending radius of 6.5 mm. Upon the addition of the niobium oxide layer, this decreased to 5 mm. Electrical resistance measurements indicated that the niobium oxide film mitigated rapid mechanical degradation of the underlying ITO electrode beyond the critical bending radius. Full article

Indium tin oxide (ITO) is a transparent conductive oxide (TCO) commonly used in the realization of optoelectronic devices needing at least a transparent electrode. In this work, ITO thin films were deposited on glass substrates by non-reactive RF magnetron sputtering, investigating the effects of power density, sputtering pressure, and substrate temperature on the electrical, optical, and structural properties of the as-grown films. High-quality films, in terms of crystallinity, transparency, and conductivity were obtained. The 120 nm thick ITO films grown at 225 °C under an argon pressure of 6.9 mbar and a sputtering power density of 2.19 W/cm² without post-annealing treatments in an oxidizing environment showed an optical transmittance near 90% at 550 nm and a resistivity of $2.10\times {10}^{-4}$ $\mathsf{\Omega }$ cm. This material was applied as the electrode of simple-structure organic light-emitting diodes (OLEDs). Full article

The manufacturing and characterization of nanographite films on substrates form the foundation for advances in materials science. Conductive graphite films are challenging products, as isolating graphite oxide is often necessary. In this study, nanographite suspensions containing non-oxidized graphite flakes were used to fabricate novel thin and ultrathin films via blade coating on industry-standard substrates. Films as thin as 346 nm were successfully fabricated. Moreover, it was possible to induce the orientation of the graphite nanoflakes via blade coating. This orientation led to electrical anisotropy; thus, the electrical behavior of the films in each orthogonal direction differed. After adjusting the coating parameters and the concentration of the nanographite flakes, the electrical conductivity ranged from 0.04 S/cm to 0.33 S/cm. In addition, with such adjustments, the transparency of the films in the visible range varied from 20% to 75%. By establishing a methodology for the tuning of both electrical and optical properties via adjustments in the nanographite suspension and coating parameters, we can fabricate resistant, conductive, and transparent films satisfying certain requirements. The results presented here can be extrapolated to enhance applications, especially for photonics and solar cells, in fields that require electrical conductive materials with high levels of transparency. Full article

Amorphous ZrO₂ thin films with increasing Mg content were deposited on quartz substrates, by dip coating method. The films are transparent in the visible domain and absorbent in UV, with an optical band gap that decreases with the increase of Mg content, from 5.42 eV to 4.12 eV. The temperature dependent conductivity measurements showed typical semiconductor comportment. The decrease of the electrical conductivity by Mg doping was related to the increase of the OH groups (37% to 63%) as seen from X-ray Photoelectron Spectroscopy. It was found out that the electrical conductivity obeys the Meyer-Neldel rule. This rule, previously reported for different disordered material systems is obtained for ZrO₂ for the first time in the literature. Exploring novel aspects of Mg-doped ZrO₂, the present study underscores the origin of the Meyer-Neldel rule explained by the small-polaron hopping model in the non-adiabatic hopping regime. Determination of the presence of such a conduction mechanism in the samples hold promise for comprehending the important aspects, which might be a concern in developing various devices based on Mg-doped ZrO₂. Full article