Zinc selenide (ZnSe) thin films were deposited by RF magnetron sputtering in specific conditions, onto optical glass substrates, at different RF plasma power. The prepared ZnSe layers were afterwards subjected to a series of structural, morphological, optical and electrical characterizations. The obtained results pointed out the optimal sputtering conditions to obtain ZnSe films of excellent quality, especially in terms of better optical properties, lower superficial roughness, reduced micro-strain and a band gap value closer to the one reported for the ZnSe bulk semiconducting material. Electrical characterization were afterwards carried out by measuring the current–voltage (I-V) characteristics at room temperature, of prepared “sandwich”-like Au/ZnSe/Au structures. The analysis of I-V characteristics have shown that at low injection levels there is an Ohmic conduction, followed at high injection levels, after a well-defined transition voltage, by a Space Charge Limited Current (SCLC) in the presence of an exponential trap distribution in the band gap of the ZnSe thin films. The results obtained from all the characterization techniques presented, demonstrated thus the potential of ZnSe thin films sputtered under optimized RF plasma conditions, to be used as alternative environmentally-friendly Cd-free window layers within photovoltaic cells manufacturing.
Zinc telluride (ZnTe) thin films were deposited by radio-frequency magnetron sputtering (RF-MS) onto optical glass coated by a silver–copper (Ag:Cu) thin film representing the back-electrode, and they were subsequently electrically contacted with an aluminum (Al) layer acting as the top-electrode. The RF-MS procedure was carried out at 50 W in argon (Ar) gas atmosphere kept at 2.5 × 10−3 mbar working pressure for 75 min at a substrate temperature of 220 °C kept constant during deposition. Morphological investigations by scanning electron microscopy allowed a first evaluation of the ZnTe film’s thickness. Optical characterization was then performed via absorption and transmission measurements in the spectral range between 300 and 1500 nm at room temperature. Subsequently, the thickness and bandgap energy of the ZnTe thin film were evaluated to be ∼508 nm and ∼2.13 eV, respectively. Moreover, they revealed high transmittance in infrared and near infrared regions of the electromagnetic spectrum. Then, the electrical measurements of Ag:Cu/ZnTe/Al “sandwich” structure (current–voltage characteristics) at six temperatures ranging from 303 to 354 K were performed, allowing the identification of the charge transport mechanisms through the structure along with their corresponding parameters. Based on the excellent optical and electrical properties, these ZnTe thin films show great potential as candidates for performant small-wavelength photodetectors.
Opto-spintronics is an emerging field that focuses on harnessing light to manipulate and analyze electron spins to develop next-generation electronic devices. This paper explores recent progress and the role of solid-state materials in opto-spintronics by focusing on key classes of materials, such as ferromagnetic semiconductors, two-dimensional (2D) transition metal dichalcogenides (TMDCs), and topological insulators. It examines the unique properties of ferromagnetic and antiferromagnetic materials and their ability to interact with light to affect spin dynamics, offering potential for improved sensing and quantum computing. By combining opto-spintronics with solid-state systems, spintronic devices could become faster and more efficient, leading to new technological advancements and scalable technologies.
The main objective of this study was to determine the variation in the properties of cadmium telluride (CdTe) thin films deposited on a p-type Si substrate by the radio frequency magnetron sputtering technique at four different working powers (70 W, 80 W, 90 W, and 100 W). The substrate temperature, working pressure, and deposition time during the deposition process were kept constant at 220 °C, 0.46 Pa, and 30 min, respectively. To study the structural, morphological, and optical properties of the CdTe films grown under the mentioned experimental conditions, X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and optical spectroscopy were used. For a better analysis of the films’ structural and optical properties, a group of films were deposited onto optical glass substrates under similar deposition conditions. The electrical characterisation of Ag/CdTe/Al “sandwich” structures was also performed using current–voltage characteristics in the dark at different temperatures. The electrical measurements allowed the identification of charge transport mechanisms through the structure. New relevant information released by the present study points towards 90 W RF power as the optimum for obtaining a high crystallinity of ~1 μm nanostructured thin films deposited onto p-Si and optical glass substrates with optical and electrical properties that are suitable for use as absorber layers. The obtained high-quality CdTe nanostructured thin films are perfectly suitable for use as absorbers in CdTe thin-film photovoltaic cells.
Nanostructured thin films are emerging into a diversified class of materials with unique optical, chemical, and physical capabilities as a result of their nanoscale characteristics. This paper provides a complete review of the manufacturing, characterization, and applications of nanostructured thin films in a range of industries such as photonics, electronics, energy storage, and medicine. The relationship between nanostructure morphology and material performance is discussed, as well as the most recent advances in fabrication technologies such as physical vapor deposition, chemical vapor deposition, and solution-based methods.
Graphene/CNT layers were deposited onto platinum electrodes of an interdigitated sensor using radio-frequency magnetron sputtering. The graphene/CNTs were synthesized in an Argon atmosphere at a pressure of (2 × 10−2–5 × 10−3) mbar, with the substrate maintained at 300 °C either through continuous heating with an electronically controlled heater or by applying a −200 V bias using a direct current power supply throughout the deposition process. The study compares the surface morphology, carbon atom arrangement within the layer volumes, and electrical properties of the films as influenced by the different methods of substrate heating. X-ray diffraction and Raman spectroscopy confirmed the formation of CNTs within the graphene matrix. Additionally, scanning electron microscopy revealed that the carbon nanotubes are aligned and organized into cluster-like structure. The graphene/CNT layers produced at higher pressures present exponential I–V characteristics that ascertain the semiconducting character of the layers and their suitability for applications in gas sensing.