QC505 : Synthesis and Characterization of CuZnS Nanostructures
Thesis > Central Library of Shahrood University > Physics > MSc > 2019
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Abstarct: In this thesis, nanostructured CuZnS (CZS) laxyers were synthesized by spray pyrolysis method. Then the structural, morphological, optical and electrical properties of the films using XRD patterns, Raman spectroscopy, FESEM images, UV-Vis spectroscopy and Hall's effect has been studied. The considered growth parameters were: molar ratio of the precursors Cu: Zn: S (2:1:4.5, 1:1:4.5, 0.4:1:4.5), deposition rate (5, 4 and 3 ml/min), annealing treatment (450 °C at one hour), substrate temperature (350 °C, 400 °C, 450 °C and 500°C) and different substrates (glass and FTO).
The structure of CZS laxyers synthesized with deposition rate of 5 ml/min at 350 °C substrate temperature with molar ratios Cu: Zn: S (1:1:4.5, 0.4:1:4.5) were amorphous and the CZS laxyer synthesized with molar ratio Cu: Zn: S (2:1:4.5) was polycrystalline. The recorded XRD pattern for the laxyer (2:1:4.5) showed the formation of binary and cubic crystalline structures of Cu2S and ZnS.
Also, XRD patterns for the samples synthesized with a deposition rates of 4 and 3 ml/min at 350°C substrate temperature confirmed the formation of Cu2S and ZnS binary and cubic crystal structures. However, the surface morphology of the laxyers significantly changed with the decrease of deposition rate. This study showed that the overall crystalline structure of the laxyers was reduced by decreasing the deposition rate. Investigation of the optical properties of these laxyers showed that the bandgap laxyers were direct. The bandgap of Cu2S phase of the laxyers was found to be in the range of 2.13-2.56 eV and it was in the range of 2.68-3.46 eV for the ZnS phase bandgap. Examination of the electrical properties of the synthesized samples showed that all samples were P-type semiconductors.
In this work also, the synthesized laxyer with molar ratio Cu: Zn: S (2:1:4.5) at 350 °C substrate temperature and deposition rate 5 ml/min was annealed temperature in 450 °C for at 1 hour in the laboratory atmosphere. The XRD pattern of this sample confirmed the formation of CZS nanostructure and also showed that the crystallinity of the laxyers was improved by the annealing. Moreover, the investigation of the optical properties of the sample showed that the bandgap of the laxyers in both Cu2S and ZnS phases) significantly reduced.
Investigation of the substrate temperature (350 °C, 400 °C, 450 °C and 500 °C) on the structure of the laxyers synthesized with molar ratio Cu: Zn: S (2:1:4.5) and deposition rate
5 ml/min showed that as substrate temperature increases, the crystallite quality decreases and the impurity phases are formed in the laxyers. Also, the investigation of the optical properties of the laxyers showed that the bandgap of the Cu2S phase was in the range of2.14-2.46 eV and the bandgap of the ZnS phase was in the range of 2.68-3.37 eV.
The effect of substrate change showed that CZS laxyers synthesized with molar ratio Cu:Zn:S (2:1:4.5) at 350 °C substrate temperature and deposition rate 5 ml/min on the FTO substrate had the better crystalline quality. Also, the optical properties of the sample showed that by changing the substrate from glass to FTO the bandgap of the Cu2S phase decreased by about % 6 and the ZnS phase increased by about % 12.
Keywords:
#Nanostructured CuZnS (CZS) #Spray Pyrolysis Method #Structural properties #Optical properties #Electrical properties Link
Keeping place: Central Library of Shahrood University
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Keeping place: Central Library of Shahrood University
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