Pulsed Laser Annealing Effect on Optical and Structural Properties of ZnS/ZnSe Heterostructures

Studies of pulsed laser annealing (PLA) on semiconductor thin films were performed to examine changes of the optical and structural parameters due to the laser heat. Thin films of ZnS/ZnSe were deposited on quartz substrates at a pressure of 8.2*10-6 mbar using PVD technique. These thin films were annealed at different laser powers using CO2 pulsed laser. Transmission and reflection spectra were recorded before and after the annealing process. A decrease in the transmission and reflection spectra after annealing is observed. The absorption coefficient, refractive index, damping coefficient and dielectric constant were calculated before and after the annealing process. Changes in the optical parameters are found after the annealing process. The energy band gaps of ZnS and ZnSe have been determined. Upon annealing, an increase in the absorption coefficient is observed which is due to an improvement in the granular nanostructure of the ZnS/ZnSe thin films. XRD patterns of the prepared samples were obtained before and after the annealing procedure and revealed an enhancement in the crystallite structure upon annealing

Variations in Optical Properties of ZnS/Cu/ZnS Nanostructures Due to Thickness Change of ZnS Cap Layer

Nanostructures of ZnS/Cu/ZnS were deposited on glass substrate using physical vapor deposition technique. The thickness of the first and last ZnS layers was altered, while the thickness of the embedded Cu layer was fixed at 50 nm. The produced nanostructures were of good quality. Spectrophotometric measurements were carried out on the nanostructures to investigate the optical properties. The transmission and reflectivity spectra were recorded and studied in detail. ZnS was selected due to its high refractive index, ease of deposition, and low cost. The copper layer was used because of its low absorption in the visible part of the spectrum and its thermal stability. The ZnS layer was found not only to anti-reflective the Cu layer, but also to stabilize the nanostructure, improve its adherence on glass substrate, and increase the film thermal resistance up to 240 °C. Furthermore, all the samples exhibit good thermal stability up to 240 °C upon annealing for two hours

Multi-Objective Optimization for Ranking Waste Biomass Materials Based on Performance and Emission Parameters in a Pyrolysis Process—An AHP–TOPSIS Approach

The current era of energy production from agricultural by-products comprises numerous criteria such as societal, economical, and environmental concerns, which is thought to be difficult, considering the complexities involved. Making the optimum choice among the various classes of organic waste substances with different physio-chemical characteristics based on their appropriateness for pyrolysis is made possible by a ranking system. By using a feasible model, which combines several attributes of decision-making processes, it is possible to select the ideal biomass feedstock from a small number of possibilities based on relevant traits that have an impact on the pyrolysis. In this study, a multi-criteria decision-making (MCDM) technique model based on the weight calculated from the analytical hierarchy process (AHP) tool has been applied to obtain a ranking of different types of agro-waste-derived biomass feedstock. The technique of order preference by similarity to ideal solution (TOPSIS) is used to examine the possibilities of using/utilizing locally available biomass. From this point of view, multi-criteria are explained to obtain yield maximum energy. The suggested approaches are supported by the experimental findings and exhibit a good correlation with one another. Six biomass alternatives and eight evaluation criteria are included in this study. Sawdust is the highest-ranking agricultural waste product with a closeness coefficient score of 0.9 out of the six biomass components that were chosen, followed by apple bagasse with 0.8. The hybrid approach model that has been built can be evaluated and validated for the ranking method using the Euclidian distance-based approximation. This study offers a unique perspective on decision-making, particularly concerning thermo-chemical conversion