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Grazing-angle x-ray diffraction was used to investigate the efficiency of vacuum-evaporated polyphenylene sulphide as an insulating overlayer on GaAs. The results showed that the material allows the formation of arsenic sulphide at the interface and the reduction of the dangling bond density. In addition, diffusion length increased while surface recombination velocity decreased. Polyphenylene sulphide allowed the stability of GaAs during annealing up to 300 degrees celsius.

Thermally stimulated exoelectron emission measurements were used to determine the native surface defects of gallium arsenide. It was shown that photoluminescence intensity of gallium arsenide was improved by plasma polymerized polythiophene grown on cleaned gallium arsenide and that this is followed by the disappearance of one the emission peaks correlated to the As(sub Ga) antisite defect.

Nanocrystalline zinc oxide-thin films have drawn the attention of researchers due to its attractive properties like transparency in visible region, abundance in nature and gas sensitivity. Nanostructured Zinc oxide (ZnO) thin films were grown on silicon, alumina and glass substrates at various substrate temperatures using a 6 kW electron beam evaporation technique. The effects of film thickness, growth temperature and substrate on the crystallinity of deposited ZnO films were investigated using X-ray diffraction, scanning electron microscopy, optical absorption and photoluminescence studies. Our studies show that good quality films are obtained for silicon substrate for a growth temperature of 250°C. Film thickness plays an important role on the evolution of the nanostructures. SEM studies combined with XRD analysis reveal that ultrathin nanorods are grown with (002), (101) and (102) orientations. All the ZnO films show room temperature photoluminescence emission bands at 394 nm and 468 nm. Optical absorption studies show strong absorption at 377 nm. Details of the structure and optical properties correlation will be presented and potential of a simple technique such as e-beam deposition to grown ZnO nanostructures suitable for optoelectronic application will be assessed. [ABSTRACT FROM AUTHOR]

Investigates the effects of the deposition and annealing conditions on the physical and electrical properties of calcium fluoride thin films. Deposition of the thin film on gallium arsenide substrate by thermal evaporation; Improvement of the interfacial electrical properties; Possibility for metal-insulator-semiconductor application.

Investigates the CuO impregnated SnO[sub 2] films using spray pyrolysis and microwave plasma chemical vapor deposition. Detection of hydrogen sulfide and methyl mercaptan; Conductivity change of films upon exposure to H[sub 2]S gas; Context of the band theory of solids.

The photoluminescence (PL) studies of powder phosphors are under rigorous study in view of the applications they have in the field of technology. Different methods are available for the preparation of rare earth ions doped in different host environment of powder phosphors. In the present work, a novel route known as sol–gel technique is employed to prepare spinel phosphor MgAl1.8Y0.2-xO4:Eux (x=2–6 mol%). Then the studies have been carried out to optimize the dopant concentration in the host lattice with the help of photoluminescence spectra. These phosphors have displayed bright red color under UV source. The emission intensities were determined and the relative fluorescence intensities have been estimated. The richness of the red color has been verified by determining their chromaticity coordinates (&Xmacr;, &Ymacr;) from the CIE standard charts. With the help of XRD, electron spin resonance (ESR), and photo-acoustic (PA) spectra of the samples prepared are also used for the confirmity of the host and analyzing of the data. [Copyright &y& Elsevier]