Showing papers by "Dominique Drouin published in 2016"

Chemical Composition of Nanoporous Layer Formed by Electrochemical Etching of p-Type GaAs

Abstract: We have performed a detailed characterization study of electrochemically etched p-type GaAs in a hydrofluoric acid-based electrolyte. The samples were investigated and characterized through cathodoluminescence (CL), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). It was found that after electrochemical etching, the porous layer showed a major decrease in the CL intensity and a change in chemical composition and in the crystalline phase. Contrary to previous reports on p-GaAs porosification, which stated that the formed layer is composed of porous GaAs, we report evidence that the porous layer is in fact mainly constituted of porous As2O3. Finally, a qualitative model is proposed to explain the porous As2O3 layer formation on p-GaAs substrate.

Novel Concept of Gas Sensitivity Characterization of Materials Suited for Implementation in FET-Based Gas Sensors.

Abstract: We propose a novel technique to investigate the gas sensitivity of materials for implementation in field-effect transistor-based gas sensors. Our technique is based on the measurement of the surface charge induced by gas species adsorption, using an electrometer. Platinum sensitivity to hydrogen diluted in synthetic air has been evaluated with the proposed charge measurement technique in the operation temperature range from 80 to 190 °C at constant H2 concentration of 4 % and for different concentrations ranging from 0.5 to 4 % at 130 °C.

Direct exchange between silicon nanocrystals and tunnel oxide traps under illumination on single electron photodetector

Abstract: In this paper we present the trapping of photogenerated charge carriers for 300 s resulted by their direct exchange under illumination between a few silicon nanocrystals (ncs-Si) embedded in an oxide tunnel layer (SiOx = 1.5) and the tunnel oxide traps levels for a single electron photodetector (photo-SET or nanopixel). At first place, the presence of a photocurrent limited in the inversion zone under illumination in the I–V curves confirms the creation of a pair electron/hole (e–h) at high energy. This photogenerated charge carriers can be trapped in the oxide. Using the capacitance-voltage under illumination (the photo-CV measurements) we show a hysteresis chargement limited in the inversion area, indicating that the photo-generated charge carriers are stored at traps levels at the interface and within ncs-Si. The direct exchange of the photogenerated charge carriers between the interface traps levels and the ncs-Si contributed on the photomemory effect for 300 s for our nanopixel at room temperature.

A manufacturable process for single electron charge detection, a step towards quantum computing

Abstract: This paper presents the fabrication, electrical characterization, and simulation of planar single electron transistors. Two single electron transistors facing each other have been used to demonstrate single charge detection. The manufacturable fabrication process combined with both single charge detection and the simulation tool are a powerful platform for quantum cellular automata that can be applied for interfacing classical computing with future quantum computing.

Selective dry etching of TiN nanostructures over SiO2 nanotrenches using a Cl2/Ar/N2 inductively coupled plasma

Abstract: An inductively coupled plasma etch process for the fabrication of TiN nanostructures over nanotopography is presented. Using a Cl2/Ar/N2 plasma, a selectivity of 50 is achieved over SiO2. The effect of N2 flow rate on the etch rates and the nonvolatile residues on TiN sidewalls is investigated. As N2 flow rate is increased up to 50 sccm, a change in the deposition of the nonvolatile residues on TiN sidewalls is observed. The current density–voltage characterizations of TiN devices fabricated with TiN nanostructure sidewalls are presented. The measured current densities of two different samples etched with low and high N2 flow rate, respectively, demonstrated the presence after cleaning of an insulating layer deposited on the sidewalls for low N2 flow rate only.

Effects of aging on nanoscale planar metal-insulator-metal tunnel junctions

Abstract: The authors use the nanodamascene fabrication process to realize planar metal-insulator-metal tunnel junctions with Ti and TiN as electrodes and TiO2 (plasma oxidation) or Al2O3 (atomic layer deposition) as insulators. The nanodamascene process allows the fabrication of junction areas as small as 20 × 10 nm2 in the current implementation, with room for further scaling. The authors use thorough electrical transport measurements together with a corresponding in-house developed simulation tool to study the aging and find solutions to stabilize junctions. The simulation tool calculates junction current using the Wentzel–Kramers–Brillouin approximation for the tunneling probability with hyperbolic junction shape taking image force into account. The tool is used for two purposes: (1) to extract key parameters of the junctions and (2) to construct a more complete understanding of the changes in current–voltage characteristics as the devices age. The study of a device aged 100 days shows an increase of up to 0.6 ...

Mesoporous germanium by high frequency bipolar electrochemical etching for optical sensor applications

Abstract: Mesoporous germanium layers (MP-Ge) were prepared with high growth rate (up to 300 nm/min) by using a new high-current-density, high-frequency bipolar electrochemical etching (BEE) process. The potential of porous semiconductor layers for optical sensing has been assessed by examining the resonance wavelength shift in the reflectance spectra before and after infiltration of ethanol.

Ba 1−x Sr x TiO 3 (x =0.4) nanoparticles dispersion for 3D integration of decoupling capacitors on glass interposer

Abstract: With the aim of scaling up and increasing the frequency of data processing within 3D integration, the placement of decoupling capacitors close to the chip is required in order to increase electrical performances of the module. Thin films deposition of materials with high permittivity (high k materials) ( 8 µF/cm2). Ba 0.6 Sr 0.4 TiO 3 nanoparticles synthesized using supercritical fluid technique and presenting attractive properties, e.g. size ∼15±2 nm, e r = 260 at 1 kHz for T = 300K, have been chosen to overcome technological limits for the realization of such high capacitance density thin films. In this paper, different approaches are proposed to disperse the nanoparticles, since their spontaneous agglomeration is critical. In order to reduce the size of these agglomerates (∼500 nm), nanoparticles are dispersed in methanol or water. In both cases, the effects of the solution concentration and the ultrasonic homogenizer power on the dispersion of nanoparticles are examined. Ultrasonication is used to break the agglomerates. Dynamic light scattering is used to monitor the changes of agglomerates size. The process to take samples from solution was optimized. In the case of dispersion in methanol, the ultrasonication (power =100W - pulse 1s/3s) of concentrated solution (C ≥ 0.1 g/L) during 10 min, leads to agglomerates corresponding to 3–5 particles (60±10nm). In the second case, the measurement of Zeta potential gives access to the optimal pH conditions (pH 9.7) for which the dispersion of Ba 0.6 Sr 0.4 TiO 3 nanoparticles is stabilized.

HfO x complementary resistive switches

Abstract: This paper proposes the fabrication, together with morphological and electrical characterizations of complementary resistive switches using a nanodamascene process. Complementary switches electrical performance are coherent with ReRAM fabricated and characterized with the same procedure that showed Ron/Roff ratios of 100. Complemetary operating voltages of V th1,3 = |0.8| V and V th2.4 = |1.1| V are obtained for 88×22 nm2 junction with 6 nm thick HfOx.

Auto-assemblage de nanoparticules de Ba0.6Sr0.4TiO3 pour la réalisation de condensateurs de découplage intégrés sur interposeur pour l’électronique 3D

Abstract: Dans le contexte de l’integration 3D des composants electroniques avec un objectif de miniaturisation et d’augmentation des vitesses de traitement de l’information, l’ajout de condensateurs de decouplage a proximite de la puce est requis afin d’augmenter les performances electriques du module. Le depot de couches minces ( 8 µF /cm2). Du fait de leur taille et leurs proprietes dielectriques, les ceramiques sont privilegiees. Les nanoparticules Ba0,6Sr0,4TiO3 synthetisees par voie supercritique, presentant des proprietes adaptees (O<20 nm et er =260 a 1kHz), ont ete ciblees pour lever des verrous technologiques permettant d’atteindre de telles densites surfaciques de capacite. Dans cette etude menee dans un contexte de collaboration franco-canadienne, l’approche de rupture proposee vise au depot d’une monocouche reposant sur l’autoassemblage de nanoparticules fonctionnalisees pour favoriser leur adhesion au substrat lors du depot par « spin coating» ou «spray coating ». Neanmoins, pour y parvenir, il est necessaire de disperser de facon optimale ces nanoparticules : en effet a cette echelle, le phenomene spontane d’agglomeration est critique. Afin de reduire la taille de tels agglomerats (500nm), les nanoparticules ont ete dispersees dans un solvant approprie : methanol ou eau. Dans les deux cas, les effets de la concentration de la solution et de la puissance de la sonde a ultrasons, sur la dispersion des nanoparticules, ont ete examines. Une sonde a ultrasons est utilisee pour briser les agglomerats. La technique de diffusion dynamique de la lumiere (DLS) a permis de suivre l’evolution de la taille de ces derniers. Le procede de prelevement en solution a egalement ete optimise. Dans le cas de la dispersion dans le methanol, l’exposition aux ultrasons (puissance = 100 W – pulse 1s /3s) de solutions concentrees (C ≥ 0,1 g / L) pendant 10 min, donne lieu a des agglomerats constitues de 3-5 nanoparticules (60 ± 10 nm). Dans le second cas, la mesure du potentiel zeta permet d'acceder aux conditions de pH pour lesquelles la dispersion des particules de Ba0,6Sr0,4TiO3 est stabilisee.

Enhancing electrical performances of metallic DG-SET based circuits by tunnel junction engineering

Abstract: The development of metallic Single Electron Transistor (SET) is extremely related to the downscaling and the electrical properties of its tunnel junctions. These tunnel junctions should insure high ON current, low OFF current and low capacitance. In this work, we propose an engineered tunnel junction based on multi-dielectric stacking to optimize the tunnel junction's characteristics. The optimized tunnel junction is demonstrated to increase ION current and the ION/IOFF ratio in Double-Gate SET (DG-SET). DG-SET based elementary circuits are demonstrating enhanced electrical characteristics.