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Diamond Substrates (diamond + substrate)

Distribution by Scientific Domains

Physics and Astronomy	83%

Selected Abstracts

Silicon incorporation in CVD diamond layers

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2005
J. Barjon
Abstract The silicon incorporation in diamond is an important issue as silicon is widely used as a substrate for the growth of polycrystalline thin films. Incorporated silicon impurities are suspected to come from the hydrogen etching of the silicon substrate. To clearly establish this point we introduced a solid source of silicon during the growth of a homoepitaxial diamond layer on a HPHT diamond substrate. A quantitative SIMS analysis revealed concentrations of silicon up to 3 × 1019 cm,3 in the diamond layer. Then we propose a scenario for the contamination of polycrystalline diamond grown on silicon substrates: after nucleation, the progressive paving of the silicon surface by 3D grains causes a fast decrease of its incorporation. At coalescence, the silicon substrate is completely covered by a 2D diamond film and the silicon concentration in diamond reaches a residual level. The investigated MPCVD and HFCVD diamond layers grown on silicon substrates present comparable features. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Diamond Transistor Array for Extracellular Recording From Electrogenic Cells

ADVANCED FUNCTIONAL MATERIALS, Issue 18 2009
Markus Dankerl
Abstract The transduction of electric signals from cells to electronic devices is mandatory for medical applications such as neuroprostheses and fundamental research on communication in neuronal networks. Here, the use of diamond with its advantages for biological applications as a new material for biohybrid devices for the detection of cell signals is investigated. Using the surface conductivity of hydrogen-terminated single-crystalline diamond substrates, arrays of solution-gate field-effect transistors were fabricated. The characterization of the transistors reveals a good stability in electrolyte solutions for at least 7 days. On these devices, cardiomyocyte-like HL-1 cells as well as human embryonic kidney cells (HEK293), which were stably transfected with potassium channels, are cultured. Both types of cells show healthy growth and good adhesion to the substrate. The diamond transistors are used to detect electrical signals from both types of cells by recording the extracellular potential. For the HL-1 cells, the shape of action potentials can be resolved and the propagation of the signal across the cell layer is visible. Potassium currents of HEK293 cells are activated with the patch-clamp technique in voltage-clamp mode and simultaneously measured with the field-effect transistors. The ion sensitivity of the diamond surface enables the detection of released potassium ions accumulated in the cleft between transistor and cell. [source]

Electrochemical deposition of Pt nanoparticles on diamond substrates

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 9 2009
Jingping Hu
Abstract Platinum nanoparticles were deposited on polished smooth, as-grown large grain and small grain diamond substrates by a potentiostatic method. The influence of deposition potential and the morphology of BDD substrates were studied. A progressive nucleation along with spherical clusters was observed on smooth BDD electrode, accompanied with a heterogeneous segregation of platinum on diamond facets of higher electrochemical activities and a weak binding to the substrate. In contrast, an instantaneous nucleation was observed on as-grown small grain and large grain BDD electrodes, with a dendritic microstructure and a much larger specific active area. The platinum decorated as-grown smaller grain BDD electrodes show a much better electrochemical stability than the other electrodes investigated. [source]

Acceptor compensation by dislocations related defects in boron doped homoepitaxial diamond films from cathodoluminescence and Schottky diodes current voltage characteristics

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 12 2006
P. Muret
Abstract This document shows that new electrically active defects can develop in the homoepitaxial layer grown on Ib diamond substrates, related to the increase of the dislocation density. Deep centres, which are able to compensate the boron acceptors, specially when the growth process allows boron incorporation below 1015 cm,3 like achieved in the samples, are identified after heating in an inert gas ambient both from photo-induced current transient spectroscopy (PICTS) and changes in Schottky diode current,voltage characteristics. Cathodoluminescence spectra are used to monitor the bands and excitonic lines, some of them being specific of dislocations. A correlation is demonstrated between the onset of properties characteristic of a compensated semiconductor and the increase of signals associated to dislocations in cathodoluminescence spectra. These modifications are thermally driven only when the samples are laid on a heating holder immerged in an inert gas, suggesting that a temperature gradient induced an additional stress which finally led to plastic relaxation of the tensile strain in the homoepitaxial layer by an increase of the dislocation density. New deep centres being simultaneously created in this degradation process, the problem of overcoming the onset of these defects for implementing high voltage devices is discussed. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Thermal transfer in SWNTs and peapods under UV-irradiation

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 11 2007
P. Puech
Abstract Results of UV irradiation experiments in vacuum on SWNTs and peapods, as followed by in-situ Raman spectroscopy with increasing laser power up to 300 mW are reported. UV micro-Raman measurements were used to record spectra free of black-body radiation. Photon absorption was found to induce both the shifting and broadening of the G+ and G, bands. The local temperature increase (up to a temperature gain of ,1000 K) was able to be reliably calculated from the band feature variation, more specifically considering the G+ band. Meanwhile, a specific sensitivity to oxidation of the nanotubes from peapods was revealed, due the fullerene-catalysed dissociation of molecular oxygen traces into active species. In addition, both silica and diamond substrates were used. The different thermal conductivity of the substrates has the effect of changing the laser power levels needed to induce structural transformations. Carrying-out UV irradiation of nanotube-based material while monitoring the induced temperature via in situ Raman spectroscopy therefore appears as a new tool likely to be useful for the nano-engineering of nanotube-based devices. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]