The initial surface chemistry and growth mechanisms of the atomic layer deposition (ALD) of metallic copper on SiO(2) surfaces are investigated using an amidinate precursor (copper(I) di-sec-butylacetamidinate, [Cu((s)Bu-amd)](2)) and molecular hydrogen. Using in situ Fourier transform infrared spectroscopy together with calculations based on density functional theory, we show that the initial surface reaction of [Cu((s)Bu-amd)](2) with hydroxylated SiO(2) takes place by displacement of one of the sec-butylacetamidinate ligands at a surface -OH site, thus forming a Si-O-Cu-((s)Bu-amd) surface species, evident by the stretching vibrations of Si-O-Cu and the chelating -NCN- bonds. Molecular hydrogen exposure during a subsequent pulse dissociates most of the sec-butylacetamidinate ligands bound to surface Cu, which releases free amidine vapor, leaving Cu atoms free to agglomerate on the surface and thus opening more reactive sites for the next [Cu((s)Bu-amd)](2) pulse. Copper agglomeration is evident in the IR absorbance spectra through the partial recovery of the intensity of SiO(2) optical phonon modes upon H(2) reduction, which was lost after the reaction of [Cu((s)Bu-amd)](2) with the initial SiO(2) surface. The thermally activated ligand rearrangement from a bridging to a monodentate structure occurs above 220 degrees C through hydrogenation of the ligand by surface hydroxyl groups after exposure to a [Cu((s)Bu-amd)](2) pulse. As Cu particles grow with further ALD cycles, the activation temperature is lowered to 185 degrees C, and hydrogenation of the ligand takes place after H(2) pulses, catalyzed by Cu particles on the surface. The surface ligand rearranged into a monodentate structure can be removed during subsequent Cu precursor or H(2) pulses. Finally, we postulate that the attachment of dissociated ligands to the SiO(2) surface during the [Cu((s)Bu-amd)](2) pulse can be responsible for carbon contamination at the surface during the initial cycles of growth, where the SiO(2) surface is not yet completely covered by copper metal.

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Surface and interface processes during atomic layer deposition of copper on silicon oxide.

The nature and properties of transition metal hydrides

Copper hydride, CuH, has been prepared by the reduction of aqueous copper sulfate using hypophosphorous acid. The polycrystalline red–brown hydride has been analysed using transmission electron microscopy, powder X-ray diffraction (PXRD) and differential scanning calorimetry, and consists of agglomerates of needle-like particles ca. 100 A in size. It is unstable at room temperature and, in an inert atmosphere, decomposes, as shown by powder XRD, to copper metal and hydrogen. Activation energies of 2.0, 8.5 and 4.7 (±0.4) kcal mol–1 were obtained for the induction, acceleratory and decay stages of the isothermal decomposition process below 100 °C. Above this temperature the solid melts.

Studies of copper hydride. Part 1.—Synthesis and solid-state stability

Novel surface enhanced Raman spectroscopy (SERS) platforms have been prepared and used for the bacteria detection. Unlike typical, expensive SERS platforms prepared from gold or silver, the presented platforms are prepared using copper. A new, simple, cost-efficient and fast high pressure method is used for platform fabrication, through the decomposition of copper hydride. The platform enhancement factors are verified using the malachite green isothiocyanate as a standard. The platforms exhibit extremely high SERS enhancement factors depending on pressure used for their preparation. The calculated enhancement factors have been found in the range between 1.5 × 106 and 4.6 × 107. The SERS spectra reproducibility is established both across a single platform and among different platforms. The average spectral correlation coefficient (Γ) has been calculated to be 0.82. Fully characterized SERS platforms have then been used for detecting Staphylococcus aureus bacteria. These novel platforms have great potential to become excellent tools for biological or medical diagnostics as an alternative to more common silver or gold SERS platforms. Copyright © 2015 John Wiley & Sons, Ltd.

Novel highly sensitive Cu-based SERS platforms for biosensing applications

Studies of the thermal decomposition of copper hydride

1
Es wurde unter Verwertung alterer Literaturangaben eine verbesserte Methode entwickelt zur Herstellung von Kupferhydrid durch Reduktion von Kupfersulfat mit unterphosphoriger Saure und zur Analyse der Praparate. Der Gehalt an CuH der bei 45° hergestellten Praparate schwankte zwischen 70—90%, der bei 0° hergestellten zwischen 65—80%, der Rest ist elementares Kupfer, das zum Teil durch langsame Zersetzung des Hydrids gebildet wird.

James C. Warf

Papers

Zur Kenntnis des Kupferhydrids, insbesondere der Kinetik des Zerfalls