Measurement of the creep behavior of thin ZrNi metallic glass films – a comparison between nanoindentation relaxation, nanoindentation creep and lab-on-chips experiments

The characterization of the time-dependent behavior of thin metallic glass films is one of the key-issue for surface engineering. Such a measurement requires loading a constant material volume located in the thin film. Unfortunately, this condition is not fulfilled in the commonly used creep nanoindentation testing, contrary to micro tensile lab-on-chip experiments or micropillar compression testing. In this paper, we show that nanoindentation relaxation is an efficient alternative to nanoindentation creep. For that purpose, an extensive study of ZrNi metallic glasses viscoplastic behavior is performed using several experimental set-up (lab on chips, nanoindentation relaxation, nanoindentation creep, constant strain rate, ...). An innovative nanoindentation methodology is used to perform long-term relaxation tests up to 10 h with excellent reproducibility. It consists in maintaining a constant contact area during the test by controlling the contact stiffness between the tip and the material. Nanoindentation relaxation, constant strain rate loading and lab-on-chips data lead to similar values of apparent activation volume and strain rate sensitivity, whereas nanoindentation creep clearly overestimates the activation volume (Fig 1). Finite element modelling of nanoindentation creep and nanoindentation relaxation also confirms this trend. We evidence, thanks to the long-term indentation relaxation test that the underlying deformation mechanisms remain unchanged on the entire investigated strain rate range. Please click Additional Files below to see the full abstract

Genotoxic effect induced by hydrogen peroxide in human hepatoma cells using comet assay

Background: Hydrogen peroxide is a common reactive oxygen intermediate generated by variousforms of oxidative stress. Aims: The aim of this study was to investigate the DNA damage capacity ofH2O2 in HepG2 cells. Methods: Cells were treated with H2O2 at concentrations of 25 μM or 50 μM for5 min, 30 min, 40 min, 1 h or 24 h in parallel. The extent of DNA damage was assessed by the cometassay. Results: Compared to the control, DNA damage by 25 μM and 50 μM H2O2 increasedsignificantly with increasing incubation time up to 1 h, but it was not increased at 24 h. Conclusions:Our Findings confirm that H2O2 is a typical DNA damage inducing agent and thus is a good modelsystem to study the effects of oxidative stress. DNA damage in HepG2 cells increased significantlywith H2O2 concentration and time of incubation but later decreased likely due to DNA repairmechanisms and antioxidant enzyme

Analytical Expressions for Distortion of SOI MOSFETs using the Volterra Series 3D

The harmonic and intermodulation distortions of SOI MOSFETs are studied with the help of the Wiener-Volterra series. Simple relationships are given and validated through Large-Signal Network Analyser measurements. The simplicity of the formulation makes it attractive to circuit designers. Furthermore, it may be used to determine the validity range of low-frequency based distortion characterization techniques. It is shown that the dominant poles of the HD for a 0.25 µm Partially Depleted SOI MOSFET lies at a few GHz, depending on the load impedance and the biasing and that its IMD3 depends on the tone separation

Direct extraction techniques of microwave small-signal model and technological parameters for sub-quarter micron SOI MOSFETs

Original extraction techniques of microwave small-signal model and technological parameters for SOI MOSFETs are presented. The characterization method combines careful design of probing and calibration structures, rigorous in situ calibration and a powerful direct extraction method. The proposed characterization procedure is directly based on the physical meaning of each small-signal behavior of each model parameter versus bias conditions, the high frequency equivalent circuit can be simplified for extraction purposes. Biasing MOSFETs under depletion, strong inversion and saturation conditions, certain technological parameters and microwave small-signal elements can be extracted directly from the measured S-parameters. These new extraction techniques allow us to understand deeply the behavior of the sub-quarter micron SOI MOSFETs in microwave domain and to control their fabrication process

Deposition time and annealing effects on morphological and optical properties of ZnS thin films prepared by chemical bath deposition

Nanocrystalline zinc sulfide (ZnS) thin films are prepared on glass substrates by chemical bath deposition (CBD) methodusing aqueous solutions of zinc chloride, thiourea ammonium hydroxide along with non-toxic complexing agent tri-sodiumcitrate in alkaline medium at 80 °C. The deposition time and annealing effects on the optical and morphological properties arestudied. The morphological, compositional, and optical properties of the films are investigated by scanning electron microscopy(SEM), X-ray energy dispersive spectroscopy (EDAX) and UV-Vis spectroscopy. SEM micrographs exhibit uniform surfacecoverage. UV-Vis (300 nm to 800 nm) spectrophotometric measurements show transparency of the films (transmittance rangingfrom 69 % to 81 %), with a direct allowed energy band gap in the range of 3.87 eV to 4.03 eV. After thermal annealing at 500 °Cfor 120 min, the transmittance increases up to 87 %

Deposition time and annealing effects on morphological and optical properties of ZnS thin films prepared by chemical bath deposition

Nanocrystalline zinc sulfide thin films were prepared on glass substrates by chemical bath deposition method using aqueous solutions of zinc chloride, thiourea ammonium hydroxide along with non-toxic complexing agent trisodium citrate in alkaline medium at 80 °C. The effect of deposition time and annealing on the properties of ZnS thin films was investigated by X-ray diffraction, scanning electron microscopy, optical transmittance spectroscopy and four-point probe method. The X-ray diffraction analysis showed that the samples exhibited cubic sphalerite structure with preferential orientation along 〈2 0 0〉 direction. Scanning electron microscopy micrographs revealed uniform surface coverage, UV-Vis (300 nm to 800 nm) spectrophotometric measurements showed transparency of the films (transmittance ranging from 69 % to 81 %), with a direct allowed energy band gap in the range of 3.87 eV to 4.03 eV. After thermal annealing at 500 °C for 120 min, the transmittance increased up to 87 %. Moreover, the electrical conductivity of the deposited films increased with increasing of the deposition time from 0.35 × 10−4 Ω·cm−1 to 2.7 × 10−4 Ω·cm−1

Underlap Channel UTBB MOSFETs for Low-Power Analog/RF Applications

In this work, we report on the significance of underlap channel architecture in Ultra Thin Body BOX (UTBB) fully-depleted (FD) SOI MOSFETs to improve analog/RF performance metrics. It is shown that at lower current levels and shorter gate lengths, underlap UTBB MOSFETs can achieve significant improvement > 1.5 times in key analog/RF metrics over devices designed with conventional S/D architecture. Analog/RF figures of merit are analyzed in terms of spacer-to-straggle ratio (s/sigma), a key parameter for the design of underlap devices. Results suggest that underlap S/D design with s/sigma ratio of 3.3 is optimum to enhance analog/RF metrics at low current levels (< 60 muA/mum). The present work provides new viewpoints for realizing future low-power analog devices/circuits with underlap UTBB FETs