Maniyeri Chandroth Santhosh Kumar

Aluminium doped tin oxide (SnO ₂ :Al) thin films (with doping concentrations 1 to15 at.%) were deposited on glass substrates through chemical spray pyrolysis and comprehensive evaluations were undertaken to determine their structural, optical, morphological, elemental, and electrical properties. SnO₂:Al thin films exhibited n -type conductivity up to 3 at.% Al ³⁺ doping. Higher doping levels resulted in a transition to p -type conductivity. The sample having 10 at.% Al doping exhibited enhanced p -type conductivity of 10.02 S cm ⁻¹ , with a hole mobility of 8.23 cm ² V ⁻¹ · s ⁻¹ and an optical transmittance of 89% in the visible range. A transparent homojunction diode with the structure p -SnO₂:Al/ n -SnO₂ was fabricated with this optimized composition, and its electrical characteristics were evaluated. To the best of our knowledge, this is the first report of a transparent SnO₂-based homojunction diode realized through this approach.

The external structure of launch vehicles is made up of metals or composites, which are insulated with multilayer materials to create a thermal protection system. In some instances, cork phenolic of the required thickness is bonded to the external structures to serve as a thermal protection system. Single-layer thermal insulation paint is applied over the cork phenolic sheet to further enhance thermal insulation. In some instances, multiple thermal insulation paints function as a thermal protection system and are coated by spraying or brushing over external structures. Conventional non-destructive testing methods, such as the eddy current technique, ultrasonic testing, and magnetic gauges, cannot be used for thickness measurement of single-layer and multilayer coatings over carbon fiber-reinforced plastic substrates. Terahertz-time domain spectroscopy in reflection mode is employed in this study for the thickness measurement of cork phenolic/single and multilayer thermal insulation systems over carbon fiber reinforced plastic substrates. A sparse deconvolution method resolves the reflected echo from each interface. The calculated thickness measurements of thermal protection systems closely match the optical microscopy reading.

Cu ₂ MgSnS ₄ (CMTS) is a highly promising material within the copper‐based chalcogenide family for electronic and photovoltaic applications. This report investigates the dependence of top electrode on the CMTS thin film‐based memory‐switching devices. Herein, and devices are fabricated and their performances are compared. CMTS thin films are deposited using vacuum spray pyrolysis. The structural studies are done using X‐ray diffraction of the films. Field emission scanning electron microscopy is used to analyze the surface morphology and electrical properties are analyzed using Hall effect measurements. I – V measurements of the devices indicate memory‐switching behavior in the positive bias region. Endurance characteristics of the devices are measured over 100 cycles. device shows an ON/OFF ratio of 408 whereas device has a lesser ON/OFF ratio of 152. Double logarithmic I – V graphs are used to analyze the switching mechanisms at different voltage ranges.

Copper-based chalcogenides have garnered growing importance in the area of thin film photovoltaics. Cu₂MgSnS₄ (CMTS) is one of the newest materials in this family of materials. It is a p-type material which finds multiple applications in the field of photovoltaics. CMTS thin films were deposited onto soda lime glass substrates using an automated vacuum spray pyrolysis technique at a substrate temperature of 300 °C and annealed at different temperatures, from 300 °C to 375 °C in steps of 25 °C. The structural, elemental, morphological, optical, and electrical properties of the material were studied. X-ray diffraction studies showed that annealing eliminates impurity phases and improves crystallinity. Field emission scanning electron microscopy studies showed improved grain size and uniform deposition of the films. The energy bandgap of the as-prepared film is 2.02 eV and that of the annealed films is around 2.5 eV. Hall measurements show that the material exhibits p-type conductivity with high values of conductivity, mobility and bulk concentration. Heterojunction devices were fabricated with a chemical bath deposited CdS as a buffer layer and spray deposited aluminium doped zinc oxide as an n-layer. Silver contacts were placed as electrodes over the top layer. The fabricated device architecture is . The junction parameters including rectification ratio, knee voltage, series resistance and ideality factor of all the devices are calculated. The device annealed at 375 °C showed an ideality factor of 2.23, which is the best among all the fabricated devices.

In this study, aluminum doped lead sulfide (PbS:Al) thin films were deposited on soda lime glass substrates using chemical bath deposition (CBD) technique. The structural, morphological, optical and electrical properties of as-deposited PbS thin films were studied as a function of Al concentration (0, 2, 4, 6, 8 at. %). The deposited films can be analyzed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), x-ray diffraction (XRD), UV-Vis-NIR spectroscopy and Hall measurement. From SEM, it was evident that the thickness of the films decreased from 750 nm (0 at. %) to 280 nm (8 at. %) with increased Al concentration. XRD analysis revealed that the prepared films exhibited face centered cubic structure without any other binary phases. The average crystallite size of the films decreased from 33.71 to 20.45 nm. The direct optical band gap values were increased from 0.90 to 1.29 eV. The optical parameters such as refractive index (n), extinction coefficient (k), real (ɛ ₁) and imaginary (ɛ ₂) parts of the dielectric constant were 1.51–2.04, 0.0035–0.0075, 2.50–6.20 and 0.005–0.16 respectively. The absorption coefficient (α) of all the deposited films was in the range of ≈10⁵ cm⁻¹. The electrical resistivity of the deposited films was found in the range of 10²–10³ Ω·cm. The overall analysis indicate that the deposited PbS:Al thin film shows promise as an absorbing layer for heterojunction solar cell devices.