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.

Cadmium (Cd)-free photodiodes based on n-type Zinc Selenide/p-type Zinc Telluride (n-ZnSe/p-ZnTe) heterojunctions were prepared by Radio Frequency-Magnetron Sputtering (RF-MS) technique, and their detailed optical and electrical characterization was performed. Onto an optical glass substrate, 100 nm gold (Au) thin film was deposited by Thermal Vacuum Evaporation (TVE) representing the back-contact, followed by the successive RF-MS deposition of ZnTe, ZnSe, Zinc Oxide (ZnO) and Indium Tin Oxide (ITO) thin films, finally resulting in the Au/ZnTe/ZnSe/ZnO/ITO sub-micrometric “substrate”-type configuration. Next, the optical characterization by Ultraviolet-Visible (UV-VIS) spectroscopy was performed on the component thin films, and their optical band gap values were determined. The electrical measurements in the dark and under illumination at different light intensities were subsequently performed. The Current–Voltage (I–V) characteristics in the dark are nonlinear with a relatively high asymmetry, following the modified Shockley–Read equation. From their analysis, the series resistance, shunt resistance, the ideality factor and saturation current were determined with high accuracy. It is worth noting that the action spectrum of the structure is shifted to short wavelengths. A sensibility test for the 420–500 nm range was performed while changing the intensity of the incident light from 100 mW/cm2 down to 10 mW/cm2 and measuring the photocurrent. The obtained results provided sufficient information to consider the present sub-micrometric photodiodes based on n-ZnSe/p-ZnTe heterojunctions to be more suitable for the UV domain, demonstrating their potential for integration within UV photodetectors relying on environmentally-friendly materials.

By doing this research we wanted to evaluate the energetical and control parameters of the group studied and to offer solutions Physical Education teacher to make their work more efficient. The methods we used in this research are: study of bibliographic material, observation and experiment, statistical and mathematical methods. The testing phase was done applying the Miron Georgescu Test. The subjects of the research are a number of 23 students from Gymnasial School “Miron Costin” from Bacau. The subjects are aged 9-11 years old and do not practice any performance sports. The study supports physical education teachers and coaches to better know the level of pupils or future athletes.

In this work, we report the preparation of nanostructured electrodes based on dense arrays of vertically-aligned copper (Cu) nanowires (NWs) to be subsequently covered by cadmium telluride (CdTe) thin films, with great potential to be used within “substrate”-type photovoltaic cells based on AII-BVI heterojunctions. In particular, the multi-step preparation protocol presented here involves an electrochemical synthesis procedure within a supported anodic aluminum oxide (AAO) nanoporous template for first generating a homogeneous array of vertically-aligned Cu NWs, which are then further embedded within a compact CdTe thin film. In a second stage, we tested three deposition methods (vacuum thermal evaporation, VTE; radio-frequency magnetron sputtering, RF-MS; and electrochemical deposition, ECD) for use in obtaining CdTe layers potentially able to consistently penetrate the previously prepared Cu NWs array. A comparative analysis was performed to critically evaluate the morphological, optical, and structural properties of the deposited CdTe films. The presented results demonstrate that under optimized processing conditions, the ECD approach could potentially allow the cost-effective fabrication of absorber layer/collecting electrode CdTe/Cu nanostructured interfaces that could improve charge collection mechanisms, which in turn could allow the fabrication of more efficient solar cells based on AII-BVI semiconducting compounds.