Thierry Baron

Bio: Thierry Baron is an academic researcher from University of Grenoble. The author has contributed to research in topics: Nanowire & Silicon. The author has an hindex of 42, co-authored 328 publications receiving 5303 citations. Previous affiliations of Thierry Baron include Alternatives & Centre national de la recherche scientifique.

Size effects in mechanical deformation and fracture of cantilevered silicon nanowires.

Abstract: Elastic modulus and fracture strength of vertically aligned Si [111] nanowires (o ) 100-700 nm) in an as-grown state have been measured using a new, multipoint bending protocol in an atomic force microscope. All wires showed linear elastic behavior, spring constants which scale with (length) 3 , and brittle failure at the wire-substrate junction. The “effective” Young’s modulus increased slightly (100 f 160-180 GPa) as wire diameter decreased, but fracture strength increased by 2-3 orders of magnitude (MPa f GPa). These results indicate that vapor-liquid-solid grown wires are relatively free of extended volume defects and that fracture strength is likely controlled by twinning and interfacial effects at the wire foot. Small wires (100 nm) grown with a colloidal catalyst were the best performers with high modulus (∼180 GPa) and fracture stress >1 GPa. One-dimensional nano-objects (nanowires, tubes, rods, springs, etc.) have attracted considerable interest lately as building blocks for electromechanical systems (oscillators, sensors, actuators), circuit interconnects, and composite materials of the future. Manipulation and exploitation of these new structures for technological applications requires detailed knowledge of material properties at the single nanostructure level. Previous studies have shown that the “effective” elasticity, strength, and plasticity of materials can all be influenced by size, shape, and “surface effects” (surface stress, oxide layers, roughness, and defects) when nanometer dimensions are involved. 1-5 Given the importance of such issues, it is no surprise that many interrogation techniques have been used to explore these effects: nanoindentation, tensile/bending (static and dynamic) tests, and resonant excitation. 1-16 In particular, atomic force microscope (AFM)based bending experiments on nanobeams and nanowires (NW) are very popular. These approaches typically measure the force required to deform a “beam” fabricated via topdown techniques, 6,7 NWs that have been artificially “fixed” to a surface with metallic pads, 8 or NWs positioned across a gap 9-12 (with and without surface pinning of the wire ends).

Experimental and theoretical investigation of nano-crystal and nitride-trap memory devices

Abstract: In this paper, we propose a thorough experimental and theoretical investigation of memory-cell structures employing discrete-trap type storage nodes, using either natural nitride traps or semiconductor nano-crystals. thus operating with a small finite number of electrons. A detailed account of static and dynamic charging/discharging phenomena occurring in these devices is given, based on bias-, time-, and temperature-dependent measurements. A comprehensive interpretation of experimental results is proposed by means of physical modeling. In particular, two different models are proposed. The first one consists in a modified floating-gate-like approach, while the second one is a trap-like approach, relying on Shockley-Read-Hall statistics. Using these two approaches, some general behavior laws for memory operation are formulated. Considerations on the suitability of each model on the particular structures are suggested.

Laser diodes based on beryllium-chalcogenides

Abstract: Beryllium chalcogenides have a much higher degree of covalency than other II–VI compounds. Be containing ZnSe based mixed crystals show a significant lattice hardening effect. In addition, they introduce substantial additional degrees of freedom for the design of wide gap II–VI heterostructures due to their band gaps, lattice constants, and doping behavior. Therefore, these compounds seem to be very interesting materials for short wavelength laser diodes. Here, we report on the first fabrication of laser diodes based on the wide band gap II–VI semiconductor compound BeMgZnSe. The laser diodes emit at a wavelength of 507 nm under pulsed current injection at 77 K, with a threshold current of 80 mA, corresponding to 240 A/cm2.

Electrical study of Ge-nanocrystal-based metal-oxide-semiconductor structures for p-type nonvolatile memory applications

Abstract: Nonvolatile memory structures using Ge nanocrystals embedded in SiO2 have been characterized by room and low temperature current–voltage and capacitance–voltage measurements. The Ge nanocrystals have been fabricated by low pressure chemical vapor deposition process which is shown to be well suited for a real control of the tunnel oxide thickness. The deposition conditions allow a separate control of nc-Ge density and size. Using capacitance–voltage characterizations on nonvolatile memory structures, we have measured the charging and discharging kinetics of holes for tunnel oxides in the range 1.2–2.5 nm. Using current–voltage measurements and simulations, we have also shown that nc-Ge are at the origin of a tunnel-assisted current. Simulations have demonstrated that the hole’s charging effects strongly reduce the current density across the nonvolatile memory structure. Combined with a good control of nc-Ge properties, the use of Ge dots with large diameters (>10 nm) seems to be a promising way for p-type ...

Statistics of electrical breakdown field in HfO2 and SiO2 films from millimeter to nanometer length scales

Abstract: The statistics of electrical breakdown field (Ebd) of HfO2 and SiO2 thin films has been evaluated over multiple length scales using macroscopic testing of standardized metal-oxide-semiconductor (TiN∕SiO2∕Si) and metal-insulator-metal (TiN∕HfO2∕TiN) capacitors (10−2mm2–10μm2 area) on a full 200mm wafer along with conductive-atomic-force microscopy. It is shown that Ebd follows the same Weibull distribution when the data are scaled using the testing area. This overall scaling suggests that the defect density is ∼1015cm−2 and Ebd is ∼40MV∕cm for nanometer-length scales; as such, breakdown in these materials is most likely initiated by bond breaking rather than punctual defects.

Prospects of Colloidal Nanocrystals for Electronic and Optoelectronic Applications

Abstract: Nanocrystals (NCs) discussed in this Review are tiny crystals of metals, semiconductors, and magnetic material consisting of hundreds to a few thousand atoms each. Their size ranges from 2-3 to about 20 nm. What is special about this size regime that placed NCs among the hottest research topics of the last decades? The quantum mechanical coupling * To whom correspondence should be addressed. E-mail: dvtalapin@uchicago.edu. † The University of Chicago. ‡ Argonne National Lab. Chem. Rev. 2010, 110, 389–458 389

Metal–Oxide RRAM

Abstract: In this paper, recent progress of binary metal-oxide resistive switching random access memory (RRAM) is reviewed. The physical mechanism, material properties, and electrical characteristics of a variety of binary metal-oxide RRAM are discussed, with a focus on the use of RRAM for nonvolatile memory application. A review of recent development of large-scale RRAM arrays is given. Issues such as uniformity, endurance, retention, multibit operation, and scaling trends are discussed.

Silicon Nanotube Battery Anodes

Abstract: We present Si nanotubes prepared by reductive decomposition of a silicon precursor in an alumina template and etching. These nanotubes show impressive results, which shows very high reversible charge capacity of 3247 mA h/g with Coulombic efficiency of 89%, and also demonstrate superior capacity retention even at 5C rate (=15 A/g). Furthermore, the capacity in a Li-ion full cell consisting of a cathode of LiCoO2 and anode of Si nanotubes demonstrates a 10 times higher capacity than commercially available graphite even after 200 cycles.

Silicon-based Nanomaterials for Lithium-Ion Batteries - A Review

Abstract: There are growing concerns over the environmental, climate, and health impacts caused by using non-renewable fossil fuels. The utilization of green energy, including solar and wind power, is believed to be one of the most promising alternatives to support more sustainable economic growth. In this regard, lithium-ion batteries (LIBs) can play a critically important role. To further increase the energy and power densities of LIBs, silicon anodes have been intensively explored due to their high capacity, low operation potential, environmental friendliness, and high abundance. The main challenges for the practical implementation of silicon anodes, however, are the huge volume variation during lithiation and delithiation processes and the unstable solid-electrolyte interphase (SEI) films. Recently, significant breakthroughs have been achieved utilizing advanced nanotechnologies in terms of increasing cycle life and enhancing charging rate performance due partially to the excellent mechanical properties of nanomaterials, high surface area, and fast lithium and electron transportation. Here, the most recent advance in the applications of 0D (nanoparticles), 1D (nanowires and nanotubes), and 2D (thin film) silicon nanomaterials in LIBs are summarized. The synthetic routes and electrochemical performance of these Si nanomaterials, and the underlying reaction mechanisms are systematically described.

Crystallinity of inorganic films grown by atomic layer deposition: Overview and general trends

Abstract: Atomic layer deposition (ALD) is gaining attention as a thin film deposition method, uniquely suitable for depositing uniform and conformal films on complex three-dimensional topographies. The deposition of a film of a given material by ALD relies on the successive, separated, and self-terminating gas–solid reactions of typically two gaseous reactants. Hundreds of ALD chemistries have been found for depositing a variety of materials during the past decades, mostly for inorganic materials but lately also for organic and inorganic–organic hybrid compounds. One factor that often dictates the properties of ALD films in actual applications is the crystallinity of the grown film: Is the material amorphous or, if it is crystalline, which phase(s) is (are) present. In this thematic review, we first describe the basics of ALD, summarize the two-reactant ALD processes to grow inorganic materials developed to-date, updating the information of an earlier review on ALD [R. L. Puurunen, J. Appl. Phys. 97, 121301 (2005)], and give an overview of the status of processing ternary compounds by ALD. We then proceed to analyze the published experimental data for information on the crystallinity and phase of inorganic materials deposited by ALD from different reactants at different temperatures. The data are collected for films in their as-deposited state and tabulated for easy reference. Case studies are presented to illustrate the effect of different process parameters on crystallinity for representative materials: aluminium oxide, zirconium oxide, zinc oxide, titanium nitride, zinc zulfide, and ruthenium. Finally, we discuss the general trends in the development of film crystallinity as function of ALD process parameters. The authors hope that this review will help newcomers to ALD to familiarize themselves with the complex world of crystalline ALD films and, at the same time, serve for the expert as a handbook-type reference source on ALD processes and film crystallinity.