SYNTHESIS AND ELECTRICAL PROPERTIES OF THIN FILMS OF FULLERITES ON THE VARIOUS SUBSTRATES

In the process of intercalation, C60 samples in the form of polycrystalline films prepared on various substrates are used. To obtain a homogeneous doping we test two geometrical set-ups of our apparatus, horizontal and vertical. In the present work we focus on the study of transport properties of the samples. We demonstrate the temperature dependence of the conductivity of doped C60 films during the doping process. The time evolutions of the sample resistivity after its exposure to the atmosphere are studied. The structural properties of the samples are examined by X-ray diffraction technique in Bragg-Brentano geometry and Raman Spectroscopy. Scanning Electron Microscopy is used to compare the surface morphology of the undoped and doped C60 films

Growth of high crystalline quality thin epitaxial CeO2 films on (1102) sapphire

We have prepared (001) oriented epitaxial CeO2 films on (1102) sapphire by metal organic chemical vapour deposition. The film thickness was in the range from 10 to 100 nm. The films exhibit extremely degree of preferred orientation, having half width at half maximum (FWHM) values of the X-ray diffraction rocking curve of the (002) CeO2, reflection as low as 0.05°. This value is comparable to the FWHM of the rocking curve of the single crystal. We show the evolution of CeO2 the film rocking curve as a function of the thickness, deposition temperature and quality of the substrate. These results are compared with atomic force microscopy images of the film surface. A possible mechanism of the growth of CeO2 films exhibiting narrow peak of the rocking curve is discussed

Growth of magnetoresistant La1-xMnO3 films on r-plane cut sapphire

We have prepared thin La1-xMnO3 films on r-plane cut sapphire by liquid source MOCVD. Tetramethylheptadionates of La and Mn (La(thd)3 and Mn(thd)3) were used as precursors and diethyleneglycol dimethyl ether as a solvent. The films were grown at deposition temperature TD = 800 °C . Temperature dependence of resistivity of the films was typical as for epitaxial films, with insulator-metal transition between 260 and 300 K and sharp decrease of the resistivity below. X-ray diffraction analysis show (100) and (110) preferred orientation of the film. Transition electron microscopy revealed epitaxial grains with grain size about 100 nm distributed in polycrystalline matrix

Properties of Thin Epitaxial Aerosol MOCVD CeO2 Films Grown on (1102) Sapphire

We have examined the properties of thin epitaxial CeO2 films prepared by aerosol MOCVD. The films were deposited on (1-102) sapphire at deposition temperatures between 500 °C and 900 °C. The best properties were observed for the film grown at high deposition temperatures. The films have thickness ≈ 0.2 µm and the full width at half maximum of the rocking curve 0.3 ° - 0.4 °. The minimal yield measured by backscattering spectrometry in the channeling mode was 5.5 %, confirming high preferred orientation of the deposited films. The epitaxial character of the CeO2 films was revealed by the measurement of the φ-scan. The aerosol MOCVD CeO2 films were found to be suitable as a buffer layer for a preparation of superconducting high-Tc films. YBa2Cu3O7 superconducting films deposited on the CeO2 / (1-102) sapphire exhibit superconducting transition temperature Tc(R=0) = 86 K

PROPERTIES OF Nb3Ge TAPE SUPERCONDUCTOR PREPARED BY CVD METHOD

Nous avons étudié les propriétés de rubans supraconducteurs de Nb3Ge, préparés par la méthode de CVD, dans les champs magnétiques jusqu'à 19 T. L'analyse au rayonnement X a été utilisée pour déterminer les phases de la couche supraconductrice. Les propriétés de nos rubans sont comparées avec les résultats obtenus ailleurs.The properties of tape Nb3Ge superconductor prepared by CVD method in magnetic fields up to 19 T were studied and X-ray phase analysis was performed. The properties of our conductor are compared with results obtained by other laboratories

Growth and Structure of Buffer Layers for High Temperature Superconducting Films

We have studied thin CeO$\text{}_{2}$ buffer layers prepared by aerosol MOCVD on (11̅02) Al$\text{}_{2}$O$\text{}_{3}$ substrate at high deposition temperature, T$\text{}_{d}$= 900°C. A texture analysis by X-ray diffraction showed a high degree of epitaxial character of CeO$\text{}_{2}$ films. A study of the microstructure by transmission electron microscopy revealed that the CeO$\text{}_{2}$ films are in a relaxed state being composed of slightly misoriented blocks surrounded by dislocations. The films are smooth, giving mean square root values of the surface roughness measured by atomic force microscopy up to 1 nm

Characterization of epitaxial LSMO films grown on STO substrates

Epitaxial manganite La_{0.67}Sr_{0.33}MnO₃ (LSMO) layers, with a thickness of 20-50 nm, are prepared on single crystal (001) SrTiO₃ (STO) substrates by pulsed laser deposition technique. Structural characterization (composition analysis, surface morphology), investigated by the Rutherford backscattering spectroscopy and atomic force microscopy, reveals the growth of stoichiometric LSMO films with a smooth surface (root-mean-square value of 0.21-1.6 nm). The prepared LSMO films possess high Curie temperature ( ≈ 412 K), low room temperature resistivity (1-2 mΩ cm) and maximum of temperature coefficient of resistivity TCR = 2.7% K¯¹ at 321 K

Ru and RuO\u3csub\u3e2\u3c/sub\u3e gate electrodes for advanced CMOS technology

\u3cp\u3eDue to the downscaling of device dimensions in CMOS technology, the introduction of metal gate electrodes and high-k dielectrics will be necessary in order to meet future performance requirements. In particular, deposition techniques such as chemical vapor deposition (CVD) and molecular beam epitaxy (MBE) have been identified as promising methods for growth of these materials. In this scope, we have analysed properties of Ru and RuO\u3csub\u3e2\u3c/sub\u3e gate electrodes in metal-oxide-semiconductor (MOS) gate stacks prepared on SiO \u3csub\u3e2\u3c/sub\u3e, atomic-layer chemical vapor deposition (ALCVD) Al \u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e3\u3c/sub\u3e and MBE Y\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e3\u3c/sub\u3e dielectric films. The Ru and RuO\u3csub\u3e2\u3c/sub\u3e films were grown by metal-organic chemical vapor deposition (MOCVD) at 250°C. The dielectric and metal gate electrode films were analysed by X-ray diffraction and time-of-flight secondary ion mass spectroscopy (TOF-SIMS). The resistivity of the films at room temperature were 20 and 150μΩcm for the Ru and RuO\u3csub\u3e2\u3c/sub\u3e films, respectively. Thermal stability of the films in forming gas (10% H\u3csub\u3e2\u3c/sub\u3e + 90% N \u3csub\u3e2\u3c/sub\u3e), nitrogen and oxygen environments was investigated by applying low temperature (420°C, 30min) and rapid thermal (800°C) annealing. The results indicate good thermal behavior of the Ru films but limited thermal stability of the RuO\u3csub\u3e2\u3c/sub\u3e films. The Ru and RuO\u3csub\u3e2\u3c/sub\u3e gate electrode workfunctions were extracted from high-frequency capacitance-voltage measurements on MOS capacitors. The obtained results are discussed in connection with applications of Ru and RuO\u3csub\u3e2\u3c/sub\u3e films as gate electrodes in CMOS technology.\u3c/p\u3