We report CdTe, CdS, and ITO thin films on glass substrates for solar cell fabrication by closed space sublimation and chemical bath deposition. CdTe and CdS thin films were sublimated to chemical treatment at 25°C in a saturated CdCl2 solution (1.04 g/100 ml methanol) and heat treated at 400°C for 30 minutes. Indium tin oxide and tellurium films were analyzed by spectrophotometer and scanning electron microscopy. It has been observed that solar cell performance can be improved by depositing a CdCl2 layer on the CdTe/CdS layers. The optical, structural, and morphological changes of CdTe and CdS surfaces on CdTe/CdS/ITO/glass solar cells due to CdCl2 solution treatment followed by annealing for 400°C were studied. Optical analysis showed about 15% decrease in transmittance after CdCl2 heat treatment in case of CdTe thin film, whereas CdS thin film demonstrated an increase of about 10–15% transmittance after CdCl2 heat treatment. Similarly, a decrease in band gap values was found for both CdTe and CdS thin films after CdCl2 heat treatment. XRD and SEM results of CdCl2 heat‐treated CdTe and CdS samples showed recrystallization, reorientation, and progressive increase in grain size. The grain sizes of CdTe and CdS samples demonstrated an increase of about 0.2 µm.
Part of the book: Modern Technologies for Creating the Thin-film Systems and Coatings
Zinc oxide (ZnO) is a unique and important metal oxide semiconductor for its valuable and huge applications with wide band gap ( 3.37 eV) and most promising candidate for gas sensor due to its high surface-to-volume ratio, good biocompatibility, stability, and high electron mobility. Due these properties, metal oxide shows good crystallinity, higher carrier mobility, and good chemical and thermal stability at moderately high temperatures. In this chapter nanostructures have been investigated, main focus being their synthesis and sensing mechanism of different toxic chemicals, synthesized by thermal evaporation through vapor transport method using vapor-liquid-solid (VLS) mechanism. The doped ZnO nanobelts showed significant enhanced sensing properties at room temperature, indicating that doping is very much effective in improving the methane CH4 sensing of ZnO nanostructures. ZnO nanowires showed a remarkable sensing response toward acetone and CH4 gas.
Part of the book: Gas Sensors