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In this paper, the electrical properties different diodes were reported. Pure and Al-doped ZnO thin films of different concentrations (Al: 1, 2 and 3 wt.%) were deposited by sol-gel dip-coating onto p-Si substrate to form heterojunctions. Zinc acetate dehydrate, Hexahydrate aluminum chloride, ethanol and ethanolamine were used as a starting material, doping, solvent and stabilizer, respectively. The dip-coating process with drying was repeated 6 times to obtain multilayer films. The morphological and electrical properties of the thin films as a function of Al concentration have been investigated using atomic force microscopy (AFM) and current-voltage (I-V) measurements at room temperature. AFM images revealed that grain sizes and surface roughness increase with increasing Al concentration. I-V characteristics of the diodes exhibited high and low currents under forward and reverse bias, respectively. The ideality factors (n), rectification ratio (RR) and barrier heights (BH) were found to range from 1.97 to 8.34, 0.84 to 5958 and 0.80 to 0.86 eV for different Al doping concentrations, respectively. These findings showed no monotonic behaviour of the calculated parameters with varying Al doping concentrations. The best electrical characteristic was obtained for the sample n-ZnO: 2 % Al/p-Si, with an ideality factor of 1.97 eV, reverse saturation current of 1.69 ± 10– 8 A, rectification ratio of 5958 at ± 2 V, and barrier height of 0.85 eV. [ABSTRACT FROM AUTHOR]

Pure and Al-doped Zin Oxide ZnO (AZO) thin films with different aluminum (Al) concentrations (0.5, 1, 2, and 3 at.%) were prepared on glass substrates by a dip-coating technique using different Zn and Al precursors. The structural, morphological, optical and electrical properties of these films were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), Atomic force electron microscopy, ultraviolet–visible spectrophotometry, photoluminescence (PL) spectroscopy and four-point probe technique. XRD results showed that the obtained AZO thin films were polycrystalline with a highly c-axis preferred (002) orientation, and the average crystallites size decreased from 29 to 25 nm with the increase in Al doping concentration. EDS microanalysis confirmed the presence of Zn, O and Al elements in the prepared films as expected. The optical study demonstrated that the ZnO thin film had a good transparency in the visible range with a maximum transmittance of 90% and the band gaps varied from 3.16 to 3.26 eV by Al doping. SEM micrographs showed a wrinkles-like morphology of the thin films that changed in density with the increase of Al concentrations. The PL emission spectra indicated that except the thin film doped with 1 at.%, other films exhibited high emission intensities under an excitation of 325 nm which allows to apply them as downconversion layers for solar cell applications. [ABSTRACT FROM AUTHOR]

Spray pyrolysis is a simple and low cost technique used for large thin films fabrication. In this paper, we reported the preparation of Cu2ZnSnS4 (CZTS) thin films with spray pyrolysis on glass substrates using different aqueous solutions. So, we chose to vary anions (S) and cations (Cu, Zn, Sn) concentrations. The purpose of this choice is the EDX analysis so that the percentage of copper is closer to 25 %; on the other hand, zinc and tin are around 12.5 % and sulfur at 50 %. The structural, chemical composition, morphological and optical properties of CZTS thin films were investigated using X-ray diffraction (XRD) and Raman spectroscopy, energy dispersive X-ray analysis (EDAX), scanning electron microscopy (SEM) and atomic force microscopy (AFM), and UV-visible spectroscopy analysis, respectively. The X-ray diffraction showed the formation of kesterite structure with dominant peaks along (112), (220) and (312) directions. Raman spectroscopy confirmed the existence of internal compressive stress in the CZTS thin films. The EDX analysis showed a better stoichiometry when optimizing the precursor concentrations. CZTS thin films showed low optical transmission and optical absorbance higher than 5×104 сm–1, which make the CZTS thin films prepared by spray pyrolysis technique suitable for CZTS solar cells. [ABSTRACT FROM AUTHOR]