D. Mariolle

Cea Leti, Grenoble, Rhône-Alpes, France

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Publications (73)133.38 Total impact

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    ABSTRACT: We report the first measurements of photo-carrier lifetimes in silicon nanocrystal-based third generation solar cells by Kelvin force microscopy and x-ray photoelectron spectroscopy under modulated frequency light illumination. A high concentration of active defects at the interface between the nanocrystals and silicon oxide matrix may be passivated by annealing under hydrogen. We found that the carrier lifetime, τ, is τ = 7 × 10(-5) s and τ = 3.5 × 10(-5) s within 10% accuracy for the hydrogen passivated and non-passivated nanocrystals, respectively. We used an exponential model to confirm the experimental potential measurements and to estimate photo-carrier lifetimes.
    Nanotechnology 06/2014; 25(26):265703. · 3.84 Impact Factor
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    ABSTRACT: Silicon nanowires (SiNWs) with axial doping junctions were synthesized via the Au-catalyzed vapor–liquid–solid growth method with the use of HCl. In this work, dopant profiling from three axially doped SiNWs with p–i, p–n and n–i–p junctions were investigated using both scanning electron microscopy (SEM) and scanning capacitance microscopy (SCM). It turns out that observed doping contrasts in SEM are also affected by the surface roughness and sample charging. In contrast, SCM allows us to delineate with sub-10 nm resolution the electrical junctions and provides a relative value of the doping concentration in each segment of the NW. SCM clearly evidences the expected doping regions within these SiNWs thanks to the addition of HCl during the growth that strongly prevents shell overgrowth. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
    physica status solidi (RRL) - Rapid Research Letters 03/2014; · 2.39 Impact Factor
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    ABSTRACT: We report on the efficiency and thermal stability of p-doping by iodine on single and randomly stacked, weakly coupled bilayer polycrystalline graphene, as directly measured by photoelectron emission microscopy. The doping results in work function value increase of 0.4–0.5 eV, with a higher degree of iodine uptake by the bilayer (2%) as compared to the single layer (1%) suggesting iodine intercalation in the bilayer. The chemistry of iodine is identified accordingly as I3− and I5− poly iodide anionic complexes with slightly higher concentration of I5− in bilayer than monolayer graphene, likely attributed to differences in doping mechanisms. Temperature dependent in-situ annealing of the doped films demonstrated that the doping remains efficient up to 200 °C.
    Applied Physics Letters 01/2014; 105(1):011605-011605-5. · 3.79 Impact Factor
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    ABSTRACT: Organic photodetectors with inverted structure are fabricated by solution process techniques. A very thin interfacing layer of polyethyleneimine leads to a homogenous interface with low work function. The devices exhibit excellent performances, in particular in terms of low dark current density, wide range linearity, high detectivity, and remarkable stability in ambient air without encapsulation.
    Advanced Materials 10/2013; · 14.83 Impact Factor
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    ABSTRACT: The influence of strain on the thermally induced dewetting mechanism of silicon films is reported. This study shows that the initial strain level in the silicon film significantly affects the final size and shape of the silicon agglomerates resulting from the film dewetting. With the increase of the biaxial strain up to 1.6%, the size of the silicon agglomerates is significantly reduced while their density increases. Moreover, the shape of the agglomerates becomes elongated when the strain favors one of the in-plane crystallographic directions to minimize the total energy of the system. A quantitative analysis of the dewetting mechanism is presented in terms of the agglomerates size and density versus the strain level. Finally, phenomenological laws are extracted, which predict the size and shape of the agglomerates.
    Journal of Applied Physics 08/2013; 114(6). · 2.21 Impact Factor
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    ABSTRACT: Structural, chemical and electronic properties of electroforming in the TiN/HfO(2) system are investigated at the nanometre scale. Reversible resistive switching is achieved by biasing the metal oxide using conductive atomic force microscopy. An original method is implemented to localize and investigate the conductive region by combining focused ion beam, scanning spreading resistance microscopy and scanning transmission electron microscopy. Results clearly show the presence of a conductive filament extending over 20 nm. Its size and shape is mainly tuned by the corresponding HfO(2) crystalline grain. Oxygen vacancies together with localized states in the HfO(2) band gap are highlighted by electron energy loss spectroscopy. Oxygen depletion is seen mainly in the central part of the conductive filament along grain boundaries. This is associated with partial amorphization, in particular at both electrode/oxide interfaces. Our results are a direct confirmation of the filamentary conduction mechanism, showing that oxygen content modulation at the nanometre scale plays a major role in resistive switching.
    Nanotechnology 02/2013; 24(8):085706. · 3.84 Impact Factor
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    ABSTRACT: The influence of strain on the thermally induced dewetting mechanism of silicon films is reported. This study shows that the initial strain level in the silicon film significantly affects the final size and shape of the silicon agglomerates resulting from the film dewetting. With the increase of the biaxial strain up to 1.6%, the size of the silicon agglomerates is significantly reduced while their density increases. Moreover, the shape of the agglomerates becomes elongated when the strain favors one of the in-plane crystallographic directions to minimize the total energy of the system. A quantitative analysis of the dewetting mechanism is presented in terms of the agglomerates size and density versus the strain level. Finally, phenomenological laws are extracted, which predict the size and shape of the agglomerates.
    Journal of Applied Physics 01/2013; 114:063502. · 2.21 Impact Factor
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    ABSTRACT: In this article we demonstrate the growth of silicon carbide pyramidal shaped nanoparticles from the carbonate contamination of (001) silicon surface. The growth process involves thermal annealing under ultra high vacuum conditions at temperatures ranging from 1050 K to 1150 K. The silicon carbide composition of the particles is confirmed by scanning Auger microscopy measurements. These particles have sizes ranging from 5 nm to 20 nm and the same orientation imposed by the underlying crystalline silicon surface. Finally, we show that the density of the nanoparticles can be controlled by monitoring the quantity of carbonated species deposited on top of the silicon surface.
    Thin Solid Films 01/2013; 527:133–136. · 1.87 Impact Factor
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    Year: 11/2012
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    Year: 11/2012
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    ABSTRACT: High density vertically aligned carbon nanotube (VACNT) forests are considered as a promising conductive material for many applications (interconnects in microelectronics or contact material layer in sliding contact applications). It is thus crucial to characterize the electrical resistance of these forests, especially in contact with the inherent top/bottom conductive substrates. This paper aims to develop an original method to determine the contribution of the different terms in this electrical resistance, which is measured with a tipless atomic force microscope used in high accuracy “force mode.” VACNT stacks with different heights on AlCu substrate with or without Au/Pd top coating are studied. The electrical contact area between the probe tip and the forest is considered to be equivalent to the classical electrical contact area between a tip and a rough surface. With this assumption, the scattering resistance of a mono-wall CNT is 14.6 kΩ μm−1, the top/bottom contact resistance is, respectively, 265 kΩ/385 kΩ. The bottom resistance divided in half is obtained by an interface substrate/CNT catalyst treatment. The same assumption leads to an effective compressive modulus of 175 MPa. These results are consistent with the values published by other authors. The proposed method is effective to optimise the CNT interface contact resistance before integration in a more complex functional structure.
    Journal of Applied Physics 08/2012; 112(4). · 2.21 Impact Factor
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    ABSTRACT: We have studied the etching properties of silicon-on-insulator (SOI) substrates in recently developed chromium-free solutions containing halogens. We have shown that the presence of halogen compounds X (I{sup -}, Br{sup -}...) in HF/HNO{sub 3}/CH{sub 3}COOH solutions is required for a selective and preferential etching on SOI. The etching rate of such solutions increases with the dissolved halogen concentrations. The chemical reactivity of Si-X (X = Br{sup -}, I{sup -}..) bonds has been analyzed by X-ray Photoelectron Spectroscopy (XPS), Pseudo-MOS (flatband potential) and Kelvin Force Microscopy (KFM) measurements. A negative shift of flatband potential values is explained by an increasing concentration of halogen compounds in the solution and a substitution of Si-H (F) bonds by Si-X bonds during the reaction. Though Si-X bonds, and more particularly Si-I bonds, have been confirmed only at trace levels using XPS, we believe that the formation of Si-X bonds is supported by a mechanism of surface dipoles. Unexpectedly, no significant change in work function could be detected using KFM measurements. Some suggestions, based on KFM technique improvements, are made to explain such results. Finally, though the interaction mechanism between silicon, fluoride, iodide, and nitric acid is not clearly elucidated by our experimental results, the formation of Si-halogen bonds is crucial for etching and defect decoration capability.
    Journal of Applied Physics 03/2012; 111(6). · 2.21 Impact Factor
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    ABSTRACT: We report the charge storage capacity of silicon nitride using Kelvin force microscopy (KFM). KFM is performed under various environments and for different thicknesses of Si3N4 (3 nm, 6 nm, and 9 nm) on top of a 10-nm SiO2 blocking oxide. We prove increased storage capacity with increased thickness and strong localization of charge characteristics — under reduced surface contamination. We have found that surface contamination is here linked with baking and presence of nitrogen flux. The structure shows strong retention under ultra high vacuum and Si3N4 thickness dependency. The total charge stored in each of these structures is calculated using Poisson solver.
    Journal of Applied Physics 01/2012; 111(2). · 2.21 Impact Factor
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    ABSTRACT: Dark current is a drastic specification for any kind of sensor and particularly for imagers dedicated to low light level. We propose here a method for optimizing the InGaAs photodiode properties. An anomalous doping profile feature revealed by scanning capacitance microscopy is counterbalanced by modifying Zn-diffusion process. We analyze the electrical results before further investigation.
    Indium Phosphide and Related Materials (IPRM), 2012 International Conference on; 01/2012
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    ABSTRACT: Spectroscopic x-ray photoelectron emission microscopy was used to study the role of the pn junction on imaging of micron scale n- and p-doped silicon patterns epitaxially grown on p- and n-type substrates, respectively. In the closed n-doped patterns, contrast with respect to open patterns is observed in both work function and Si 2p binding energy. Reverse bias at the junction creates a shift of electrical potential induced by photoemission in the closed patterns. No shift is observed for p-doped patterns on n substrate, pointing to the importance of doping combination and pattern geometry in the contrast observed in electron microscopy.
    Applied Physics Letters 11/2011; 99(20). · 3.79 Impact Factor
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    ABSTRACT: In this work, we report a series of Kelvin Force Microscopy (KFM) measurements, suitable to observe the topography and the contact potential difference (CPD) distribution of the following stack: CdTe∕CdS∕ITO∕glass. The sample is prepared by mechanical polishing after cleavage to decrease the roughness. In order to have a better understanding of the charge transport inside the solar cell and to vary the Fermi level pinning effect, different bias are applied to the sample. The CPD variations with different bias on cross-section in dark condition are presented. We observe the reverse bias widens the CdTe∕CdS depletion region. Under illumination, electron and holes are generated near the interface and varies the CPD distribution. Additionally, the chemical composition of each layer has been investigated by nano-Auger electron spectroscopy (AES). We observe the interdiffusion at the CdTe∕CdS interface and determine the composition of the active layers to be CdTe∕CdS0.7Te0.3.
    AIP Conference Proceedings. 11/2011; 1395(1).
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    ABSTRACT: Thanks to their outstanding electrical properties and , carbon nanotubes (CNTs) are promising candidate to replace Cu in advanced interconnects , , , , and . In damascene based CNT via integration scheme, CNTs growth occurs on the whole surface of the wafers: in vias, but also on top surfaces [5]. CNTs on top are subsequently removed by polishing. In this paper, an alternative integration scheme is proposed which avoids CNTs on top. Thanks to careful choice of top surface (TiN) and bottom electrode (doped silicon) materials, CNT growth occurs only in vias. Dense growth (6 × 1011 CNTs/cm2) of small multi wall CNTs is achieved in vias over doped poly-silicon lines. Good encapsulation of CNTs is obtained with SACVD SiO2 or ALD Al2O3 materials. Thanks to polishing of emerging CNTs, planarized CNT vias are obtained. Initial electrical measurements by conductive AFM show the conductivity of these CNT vias.
    Microelectronic Engineering. 01/2011;
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    ABSTRACT: Scanning probe microscopy (SPM) characterizations were performed on nonintentionally doped n-type ZnO nanopillars (NPs) embedded in a polymer matrix. Transport properties investigations using scanning capacitance microscopy revealed local p-type space charge regions spreading over the outer shell of the polymer-coated ZnO NP. Correlatively, different electrical behaviors were found for the core and shell parts of the NPs using scanning spreading resistance microscopy. From SPM imaging at various voltage biases and local I-V curves, an electrical transport analysis was carried out based on surface states arising from the surrounding environment. Surface barrier potential inducing p-type conductivity in polymer-coated ZnO NPs was discussed and estimated to amount to several hundreds of milli-electron-volt. As a further consequence a critical diameter under which full p-type conductivity occurs in the NPs was demonstrated both theoretically and experimentally.
    Journal of Applied Physics 07/2010; · 2.21 Impact Factor
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    ABSTRACT: We report on the VLS (vapour-liquid-solid) fabrication and characterization of in situ axially doped silicon nanowires (SiNWs) at both ends, and on their integration into a bottom gate-top contact geometry on both rigid and flexible substrates to realize field-effect transistors (FETs). To improve contact resistance between SiNWs and source/drain electrodes, we axially tuned the level of doping at both ends of the SiNWs by sequential in situ addition of PH(3). Characterisation of SiNWs by scanning spreading resistance microscopy in the device configuration allowed us to determine precisely the different sections of the SiNWs. The transfer to flexible substrates still allowed for workable FET structures. Transistors with electron mobilities exceeding 120 cm(2) V(-1) s(-1), I(on)/I(off) ratios greater than 10(7) and ambipolar behaviour were achieved.
    Nanoscale 05/2010; 2(5):677-80. · 6.73 Impact Factor