P.K. Mochahari; Ananta Rajbongshi; Nava Choudhury; F. Singh; K.C. Sarma
Abstract
Cadmium sulphide (CdS) nanostructured films were prepared by chemical bath deposition (CBD) method at room temperature. The prepared films were subjected to swift heavy ion (SHI) irradiation by using 100 MeV Si 8+ ion beams at various fluences from 1x10 11 to 1x10 13 ions/cm 2 . Structural, morphological, ...
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Cadmium sulphide (CdS) nanostructured films were prepared by chemical bath deposition (CBD) method at room temperature. The prepared films were subjected to swift heavy ion (SHI) irradiation by using 100 MeV Si 8+ ion beams at various fluences from 1x10 11 to 1x10 13 ions/cm 2 . Structural, morphological, optical properties of the pristine and irradiated films were characterized by X-ray diffractrometer (XRD), high resolution transmission electron microscope (HRTEM), UV-Vis spectroscopy and Raman spectroscopy. XRD study confirms the formation of nanocrystalline cubic phase in all the films. The crystallite size is found to increase from 7nm to 9 nm and shift of peak positions are observed due to irradiation. The lattice strain and dislocation density of the samples are of the order of 10 -3 and 10 16 m -2 respectively and the values are found to decrease upon irradiation. HRTEM images show that the shapes of the particles are nearly spherical and the selected area electron diffraction (SAED) pattern of HRTEM have also supported the formation of cubic phase CdS. The optical absorption spectra exhibit shift in the fundamental absorption edge and the optical band gap decreases from 2.585eV to 2.513 upon SHI irradiation. Three intense Raman lines for pristine as well as irradiated CdS have been observed and all the samples show shift in Raman lines relative to bulk CdS due to phonon localization. The SHI irradiation on chemically deposited CdS films is an important tool used for modification of structural, morphological and optical properties of the films for possible applications in device fabrication.
V. V. Siva Kumar; Sunil Ojha;D. Kanjilal; F. Singh
Abstract
In the present study we report the influence of variation in amount of Zn on growth and optical properties of thin films of ZnO nanocrystals in silica matrix deposited by rf magnetron co-sputtering with substrate heating at 200 o C. RBS studies indicate change in the concentration of Zn in the films ...
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In the present study we report the influence of variation in amount of Zn on growth and optical properties of thin films of ZnO nanocrystals in silica matrix deposited by rf magnetron co-sputtering with substrate heating at 200 o C. RBS studies indicate change in the concentration of Zn in the films while Raman spectroscopy measurements indicate presence of excess zinc with different concentration. The XRD spectra of the thin films shows the formation of strong ZnO phase nanocrystals with different sizes in different films while the UV-VIS spectra shows variation in the band edge energy of the ZnO nanocrystals for these films. FT-IR spectra of the films show the Zn-O, Zn-O-Si and Si-O-Si vibrational features related to ZnO, Zn2SiO4 and SiOx phases in the films. The results suggest growth of stable ZnO nanocrystals in silica matrix having better phase and optical quality with increase in the Zn concentration in the thin films, which may be useful in optical applications of ZnO.