Elaboration of a Novel Design Pirani Pressure Sensor for High Dynamic Range Operation and Fast Response Time

AbstractWe report a novel design for realizing Pirani sensor with a working range from a 1kPa up to pressure over than atmospheric one. The sensor is specifically designed to achieve high sensitivity, fast response time and high robustness. The proof of concept is composed of four metallic resistors interconnected to form a Wheatstone bridge. Two of them act simultaneously as the heating and sensing elements and the two others are used as a temperature reference. The heating element consists of a metallic wire of platinum Pt (3μm width, 1mm length) maintained on each lateral side by periodic silicon oxide SiO2 micro-bridges. The sensor design, fabrication technologies, electrical characterizations and voltage-pressure responses are described and shown. A future perspective is given, which describe the extension of this concept to elastic wave transduction of pressure using a combination of heater element and thin plate elastic waveguide

Electronic and physico-chemical properties of nanmetric boron delta-doped diamond structures

Heavily boron doped diamond epilayers with thicknesses ranging from 40 to less than 2 nm and buried between nominally undoped thicker layers have been grown in two different reactors. Two types of [100]-oriented single crystal diamond substrates were used after being characterized by X-ray white beam topography. The chemical composition and thickness of these so-called deltadoped structures have been studied by secondary ion mass spectrometry, transmission electron microscopy, and spectroscopic ellipsometry. Temperature-dependent Hall effect and four probe resistivity measurements have been performed on mesa-patterned Hall bars. The temperature dependence of the hole sheet carrier density and mobility has been investigated over a broad temperature range (6K<T<450 K). Depending on the sample, metallic or non-metallic behavior was observed. A hopping conduction mechanism with an anomalous hopping exponent was detected in the non-metallic samples. All metallic delta-doped layers exhibited the same mobility value, around 3.660.8 cm2/Vs, independently of the layer thickness and the substrate type. Comparison with previously published data and theoretical calculations showed that scattering by ionized impurities explained only partially this low common value. None of the delta-layers showed any sign of confinement-induced mobility enhancement, even for thicknesses lower than 2 nm.14 page

Micro-capteur à fort gradient de température pour des mesures de frottement pariétal et de direction de l'écoulement

International audienceWe present an efficient and high-sensitive thermal micro-sensor for near wall flow parametersmeasurements. By combining substrate-free wire structure and mechanical support using siliconoxide micro-bridges, the sensor achieves a high temperature gradient, with wires reaching 1 mmlong for only 3 µm wide over a 20 µm deep cavity. Elaborated to reach a compromise solutionbetween conventional hot-films and hot-wire sensors, the sensor presents a high sensitivity to thewall shear stress and to the flow direction. The sensor can be mounted flush to the wall for research studies such as turbulence and near wall shear flow analysis, and for technical applications, such as flow control and separation detection. The fabrication process is CMOS-compatible and allows on-chip integration. The present letter describes the sensor elaboration, design, and micro-fabrication, then the electrical and thermal characterizations, and finally the calibration experiments in a turbulent boundary layer wind tunnel

Dual role of 3C-SiC interlayer on DC and RF isolation of GaN/Si-based devices

International audienceThe impact of Cubic Silicon Carbide (3C-SiC) transition layer on breakdown voltage and frequency performance of GaN high electron mobility transistors is investigated. A combination of distinct material and device characterizations techniques, including Raman spectroscopy, coplanar waveguides, electrical measurements, and Technology Computer-Aided Design (TCAD) simulations, are adopted to inspect the role of the 3C-SiC interlayer. Raman spectra reveal a good quality of the 3C-SiC layer, similar to the mono-crystalline 3C-SiC spectra. A relatively low transmission loss of ∼0.16 dB/mm at 40 GHz is measured for the device with 3C-SiC layer, rather than 2.1 dB/mm for the device without 3C-SiC. In addition, a soft breakdown voltage around 1530 V at 1 μA/mm is achieved, which is three times larger compared with that of the conventional device. The failure mechanism, related to carrier injection at the nucleation layer, is not observed in the structure with the 3C-SiC layer. Instead, TCAD simulations disclose a substantial improvement of the buffer/substrate interface through the suppression of an interface current path

Developments, characterization and proton irradiation damage tests of AlN detectors for VUV solar observations

For next generation spaceborne solar ultraviolet radiometers, innovative metal-semiconductor-metal detectors based on wurtzite aluminum nitride are being developed and characterized. A set of measurement campaigns and proton irradiation damage tests was carried out to obtain their ultraviolet-to-visible characterization and degradation mechanisms. First results on large area prototypes up to 4.3 mm diameter are presented here. In the wavelength range of interest, this detector is reasonably sensitive and stable under brief irradiation with a negligible low dark current (3-6 pA/cm2). No significant degradation of the detector performance was observed after exposure to protons of 14.4 MeV energy, showing a good radiation tolerance up to fluences of 1 × 1011 protons/cm2. © 2013 Elsevier B.V. All rights reserved

A cost-effective technology to improve power performance of nanoribbons GaN HEMTs

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Diamond Coated LW-SAW Sensors-Study of Diamond Thickness Effect

This study focuses on the fabrication and characterization of Love wave surface acoustic wave (LW-SAW) sensors with a thin nano-crystalline diamond (NCD) coating with an integrated microfluidics system. The effect of diamond layer thickness on the acoustic wave phase velocity and the sensor’s sensitivity have been investigated experimentally and compared with theoretical simulations. The fabricated sensors have been tested with a several liquids using a home-made microfluidics system