Search results for "electronics"
showing 10 items of 4340 documents
One-step formation of nanostructures on silicon surfaces using pure hydrogen-radical-initiated reactions
2013
One-step formation of silicon nanowires, sheets, and texture surface on a silicon substrate has been achieved using hydrogen-radical etching reactions. Metallic tungsten and for comparison purposes a tungsten hot wire, were used as catalysts for the hydrogen-molecular cracking. It was shown that a variety of surface structures on silicon such as inverted pyramid texture, V-groove texture, dense silicon nanowire growth over texture, and nanosheet structure can be obtained by controlling the process conditions. The obtained results suggested that the formation of nanotungsten silicide particle is an essential prerequisite to obtain these structures. The particles work as an etching mask again…
Detection and quantification of lung cancer biomarkers by a micro-analytical device using a single metal oxide-based gas sensor
2018
International audience; The analysis of exhaled volatile organic compounds (VOCs) related to lung cancer is a very promising wayin medical diagnosis because it is non-invasive and much less expensive than traditional medical analysisused so far. In that sense, a silicon micro-analytical platform consisting of a micro-preconcentrator cou-pled to a silicon spiral gas chromatographic micro-column was built, and a metal oxide-based gas sensorwas used as a miniaturized gas detector. This micro-fabricated device was successfully tested to selec-tively detect low concentrations of VOCs considered as lung cancer biomarkers, within a few minuteseven in presence of high concentrations of water vapor …
Phonon-plasmon coupling in Si doped GaN nanowires
2016
Abstract The vibrational properties of silicon doped GaN nanowires with diameters comprised between 40 and 100 nm are studied by Raman spectroscopy through excitation with two different wavelengths: 532 and 405 nm. Excitation at 532 nm does not allow the observation of the coupled phonon–plasmon upper mode for the intentionally doped samples. Yet, excitation at 405 nm results in the appearance of a narrow peak at frequencies close to that of the uncoupled A 1 (LO) mode for all samples. This behavior points to phonon–plasmon scattering mediated by large phonon wave-vector in these thin and highly doped nanowires.
Electron-phonon heat transport and electronic thermal conductivity in heavily doped silicon-on-insulator film
2003
Electron–phonon interaction and electronic thermal conductivity have been investigated in heavily doped silicon at subKelvin temperatures. The heat flow between electron and phonon systems is found to be proportional to T6. Utilization of a superconductor–semiconductor–superconductor thermometer enables a precise measurement of electron and substrate temperatures. The electronic thermal conductivity is consistent with the Wiedemann–Franz law. Peer reviewed
Nanocrystal metal-oxide-semiconductor memories obtained by chemical vapor deposition of Si nanocrystals
2002
We have realized nanocrystal memories by using silicon quantum dots embedded in silicon dioxide. The Si dots with the size of few nanometers have been obtained by chemical vapor deposition on very thin tunnel oxides and subsequently coated with a deposited SiO2 control dielectric. A range of temperatures in which we can adequately control a nucleation process, that gives rise to nanocrystal densities of ∼3×1011 cm−2 with good uniformity on the wafer, has been defined. The memory effects are observed in metal-oxide-semiconductor capacitors or field effect transistors by significant and reversible flat band or threshold voltage shifts between written and erased states that can be achieved by …
Characterization of SiPM properties at liquid nitrogen temperature
2016
SiPM operation at cryogenic temperatures fails for many common devices. A particular type with deep channels in the silicon substrate instead of quenching resistors was thoroughly characterized from room temperature down to liquid nitrogen temperature by illuminating it with low light levels. The devices were mounted in vacuum with the temperature stabilized to allow long-term operation. SiPM signals from a LED pulser were acquired with single-pixel resolution. Generalized fits to the charge collection spectra were used to extract properties like single-pixel gain, inter-pixel variation, breakdown voltage, and photon detection efficiency. With these measurements a deeper investigation of th…
Effects of partial self-ordering of Si dots formed by chemical vapor deposition on the threshold voltage window distribution of Si nanocrystal memori…
2006
We study the role that the denuded zone around Si nanocrystals obtained by chemical vapor deposition plays on the fluctuations of the dot surface coverage. In fact, the capture mechanism of the silicon adatoms in the proximity of existing dots restricts the number of possible nucleation sites, the final dot size, and the dot position, thus driving the process toward partial self-order. We numerically evaluate the relative dispersion of surface coverage for several gate areas and compare the results to the fully random case. The coverage dispersion is related to the fluctuations from bit to bit of the threshold voltage window (Δ Vth) distribution of nanocrystal memories. The evaluations, com…
Effect of germanium addition on the properties of reactively sputtered ZrN films
2005
For the first time, Zr-Ge-N films were deposited on silicon and steel substrates by sputtering a Zr-Ge composite target in reactive Ar-N2 mixture. The films were characterised by electron probe microanalysis, X-ray diffraction, micro-Raman spectroscopy and depth-sensing indentation. The effects of the Ge content and substrate bias voltage on the films' structure, internal stress, hardness and oxidation resistance were investigated. Substrate bias strongly influenced the chemical composition of the films being observed by means of a steep decrease in the Ge content for negative bias voltages higher than -80 V. In these cases, a significant hardness improvement was registered. For -100 V bias…
Changes in Amorphous Hydrogenated Carbon Films by Ultraviolet and Infrared Laser Irradiation
2013
Amorphous hydrogenated carbon lms were formed on the Si (100) wafers by a direct-ion beam deposition method from pure acetylene and acetylene hydrogen gas mixtures. The lms were irradiated with a nanosecond Nd:YAG laser working at the rst harmonics (λ1 = 1064 nm), the fourth harmonics (λ4 = 266 nm) or with a Nd:YVO4 laser working at the third harmonic (λ3 = 355 nm). The lms were studied by the Raman scattering, micro-Fourier transform infrared and Fourier transform infrared spectroscopies, null-ellipsometry, optical and scanning electron microscope, and Vickers hardness method. Irradiation by the wavelength λ1 = 1064 nm leads to graphitization and formation of the silicon carbide, because o…
Scanning electron microscopy analysis of defect clusters in multicrystalline solar grade silicon solar cells
2014
Solar cells from an identical commercial manufacturing unit have been investigated by electroluminescence to first detect the defect clusters. A further analysis has been done by scanning electron microscopy in secondary electron imaging mode to understand the propagation mechanism of defects. It appears that defect cluster boundaries can be very sharp or spread in the bulk with little apparent effect on the overall cell efficiency. And it is shown that grain boundaries act clearly as arrests to further propagation of these defects.