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Size tunability and enhanced optical properties of cadmium sulphide (CdS) nanoparticles entrapped in polymethyl methacrylate (PMMA) matrix were presented in this paper. The three-dimensional quantum confinement of CdS in the PMMA matrix was achieved by the in situ technique. X-ray diffraction results show the presence of CdS in the PMMA matrix for higher concentration of CdS nanoparticles (1:20). The particle size and energy band gap were determined by UV-visible spectroscopy. The photoluminescence spectrum shows broadened surface trapped emissions that are shifted towards the blue region. The formation of CdS and its stoichiometric ratio has been confirmed using X-ray photoelectron spectroscopy. The transmission electron microscope results reveal the uniform distribution of nanometre sized particles in the PMMA matrix. The size distribution of CdS nanoparticles in the nanocomposite was carried out by atomic force microscope. [ABSTRACT FROM AUTHOR]

Cadmium zinc telluride (CdZnTe) or CZT, a direct band gap semiconductor is used in a variety of applications such as radiation detectors, photo refractive gratings, solar cells and electro-optic modulators. In the present investigation, we have studied the influence of substrate temperature on the structure, morphology and optical properties of radio frequency magnetron sputtered cadmium zinc telluride (Cd0·4Zn0·1Te0·5) thin films deposited onto well cleaned glass substrates. CZT thin films of different thicknesses in the range from 128 to 549 nm with stoichiometric composition were prepared by optimising the process parameters. Transmittance spectra of thin films were recorded using UV-vis spectrophotometer in the wavelength range of 200 to 1500 nm and the optical band gap was determined. Surface topography of CZT thin films was analysed using atomic force microscopy and the root mean square roughness was determined. X-ray diffraction and transmission electron microscopy analysis revealed the presence of zinc blende structure exhibiting the predominant (111) and other planes along (220) and (311) directions. The d-spacing and crystallite size were also calculated. The results are discussed. [ABSTRACT FROM AUTHOR]

We have investigated the effect of post-deposition annealing on the composition and electrical properties of alumina (Al2O3) thin films. Al2O3 were deposited on n-type Si <100> substrates by dc reactive magnetron sputtering. The films were subjected to post-deposition annealing at 623, 823 and 1023 K in vacuum. X-ray photoelectron spectroscopy results revealed that the composition improved with post-deposition annealing, and the film annealed at 1023 K became stoichiometric with an O/Al atomic ratio of 1·49. Al/Al2O3/Si metal-oxide-semiconductor (MOS) structures were then fabricated, and a correlation between the dielectric constant εr and interface charge density Qi with annealing conditions were studied. The dielectric constant of the Al2O3 thin films increased to 9·8 with post-deposition annealing matching the bulk value, whereas the oxide charge density decreased to 3·11×1011 cm−2. Studies on current-voltage IV characteristics indicated ohmic and Schottky type of conduction at lower electric fields (<0·16 MV cm−1) and space charge limited conduction at higher electric fields. [ABSTRACT FROM AUTHOR]