Thin films of antimony sulfide have been deposited from chemical baths containing antimony trichloride and sodium thiosulfate maintained at 10°C. Upon annealing in nitrogen at 300°C for 1 h, the films become photosensitive with photo-to dark-current ratio of two to three orders of magnitude at 2 kW m2 tungsten halogen radiation. The annealed films are crystalline with an X-ray diffraction pattern matching that of stibnite, 5b753, (JCPDS 6-0474) and show an optical bandgap of 1.78 eV. Deposition of a thin film of CuS on the antimony sulfide thin film and subsequent annealing in nitrogen at 250°C for 1 h produces films with acceptable solar control characteristics: integrated visible transmittance, 15%; integrated visible reflectance, 12%; integrated infrared transmittance, Tir, 14%; integrated infrared reflectance, R1,, 36%; and a shading coefficient of about 0.35. The X-ray diffraction patterns of the annealed 5b757-CuS thin films indicate the formation of a ternary compound with the structure of famatinite, Cu35b54.

Cadmium sulphide thin films showing photo-to-dark conductivity ratio up to l O9 and photoconductivity up to 3 Cl'. ' cm " for white illumination -300 W m -* can be prepared from chemical baths containing thiourea and triethanolamine complex of cadmium ions. The photocurrent decay time depends on the bath temperature and the duration of storage and it ranges from a few seconds to lo4 S per decade. The optical transmission of the films also varies significantly: from about 10% to 70-80% (above the band-gap absorption), depending on the deposition conditions. The high activation energy -1 eV for dark conductivity a s well a s the high photosensitivity suggest the nearly stoichiometric nature of the films. The implications of these characteristics in various opto-electronic applications are discussed.

The adsorption and formation of DNA and cationic surfactant complexes at the silica-aqueous interface have been studied by ellipsometry. The interaction between the DNA-surfactant complexes at the mica-aqueous interface has been determined by the interferometric surface force apparatus. Adsorption was as expected not observed on negatively charged hydrophilic surfaces for DNA and when DNA-cationic surfactant complexes were negatively charged. However, adsorption was observed when there is an excess of cationic surfactant, just below the point of phase separation. The adsorption process requires hours to reach steady state. The adsorbed layer thickness is large at low surface coverage but becomes more compact and thinner at high coverage. A long-range repulsive force was observed between adsorbed layers of DNA-cationic surfactant complexes, which was suggested to be of both electrostatic and steric origin. The forces were found to be dependent on the equilibration time and the experimental pathway.

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Raman spectroscopy results obtained under visible (non-resonant) and UV (resonant) excitation for nanocrystalline ZnO, ZnO:Mn and ZnO:Mn:Al thin films grown by radio frequency magnetron sputtering are presented and compared. The origin of the multiple longitudinal optical (LO) phonon Raman peaks, strongly enhanced under resonance conditions, and the effects of the dopants on them are discussed in the framework of the 'cascade' model. It is suggested that the observed suppression of the higher-order LO phonon lines for ZnO:Mn:Al is caused by the dissociation of excitons in the heavily n-type doped material. On the basis of the cascade model interpretation of the higher-order Raman peaks in the resonant spectra, the LO phonon frequencies for wavevectors away from the Γ point are evaluated and compared to previously published phonon dispersion curves.