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Papers by Catherine Dubourdieu
Dielectric Properties and Flat-Band Voltages of Doped HfO2
ECS Meeting Abstracts, 2010
ABSTRACT The control of high-symmetry phases of HfO2 can be achieved by cationic substitution for... more ABSTRACT The control of high-symmetry phases of HfO2 can be achieved by cationic substitution for Hf. The electrical properties of HfO2 cubic phase stabilized by addition of yttrium or magnesium are investigated. The introduction of moderate Y or Mg doping content (similar to 10-15 at.%) in HfO2 results in an enhancement of the dielectric constant. No degradation of the interface state density and leakage current is noticed. The flat-band voltage is shifted to positive voltages, similarly as it was observed for monoclinic and cubic pure HfO2 thin films. This result confirms that the contribution of the SiO2/high-kappa interface to the flat-band voltage depends on the structural high-kappa properties.
arXiv (Cornell University), Apr 27, 2022
Conductive bridge random access memory devices such as Cu/SiO2/W are promising candidates for app... more Conductive bridge random access memory devices such as Cu/SiO2/W are promising candidates for applications in neuromorphic computing due to their fast, low-voltage switching, multiple-conductance states, scalability, low off-current, and full compatibility with advanced Si CMOS technologies. The conductance states, which can be quantized, originate from the formation of a Cu filament in the SiO2 electrolyte due to cation-migration-based electrochemical processes. A major challenge related to the filamentary nature is the strong variability of the voltage required to switch the device to its conducting state. Here, based on a statistical analysis of more than hundred fifty Cu/SiO2/W devices, we point to the key role of the activation energy distribution for copper ion diffusion in the amorphous SiO2. The cycleto-cycle variability is modeled well when considering the theoretical energy landscape for Cu diffusion paths to grow the filament. Perspectives of this work point to developing strategies to narrow the distribution of activation energies in amorphous SiO2.
High k SrTiO3 Perovskite on Si/SiO2: CVD Growth, Interface Engineering and Dielectric Properties
ECS Meeting Abstracts, 2009
not Available.
Nature communications, Jan 29, 2024
Strain and Cation Stoichiometry in Epitaxial BaTiO3 Thin Films Grown on Silicon
International audienc
Epitaxial pyroelectric thin films on silicon for thermal energy harvesting
Growth parameters and tetragonality at the nanoscale of MBE epitaxial BaTiO3 films on Si
Thermal energy harvesting through epitaxial pyroelectric oxide films integrated on silicon
Integration of functional oxides on silicon for nanoelectronics and energy
Electro-optic modulation with functional oxides monolithically integrated on silicon
june 29-july 4 2014International audienceno abstrac
Epitaxial pyroelectric Pb(Zr,Ti)O3 thin films on silicon for thermal energy harvesting
11-15 mai 2015International audienceno abstrac
Pulsed-MOCVD Growth of Transition Metal Oxides
ECS Meeting Abstracts, 2005
not Available.
Toward van der Waals epitaxy of transferable ferroelectric barium titanate films via a graphene monolayer
Journal of Materials Chemistry C, 2020
Transferable highly (001)-oriented textured ferroelectric BaTiO3 thin films have been achieved on... more Transferable highly (001)-oriented textured ferroelectric BaTiO3 thin films have been achieved on a graphene monolayer for wearable devices like sensors and actuators for future “Internet of Things” era.
Correlation between the microwave surface resistance and the volumic fraction of a-axis grains in YBa2Cu3O7−x films
Physica C: Superconductivity, 1998
A quantitative study of the effect of a-axis grains (the a-axis is perpendicular to the substrate... more A quantitative study of the effect of a-axis grains (the a-axis is perpendicular to the substrate plane) on the microwave surface resistance in epitaxial YBa2Cu3O7−x films is reported. The films were grown by Metal Organic Chemical Vapor Deposition on MgO and LaAlO3 substrates. The fraction of a-axis grains %a has been varied in the range 0–70% by changing the oxygen partial pressure during the growth. A clear correlation between the surface resistance Rs(0.85Tc), measured at 87 GHz, and the volumic fraction %a is found. At variance, the residual surface resistance Rs(4.2 K) does not correlate to %a.
Nature Physics, 2017
Ferroelectricity on the nanoscale has been the subject of much fascination in condensed-matter ph... more Ferroelectricity on the nanoscale has been the subject of much fascination in condensed-matter physics for over half a century. In recent years, multiple reports claiming ferroelectricity in ultrathin ferroelectric films based on the formation of remnant polarization states, local electromechanical hysteresis loops, and pressure-induced switching were made. However, similar phenomena were reported for traditionally non-ferroelectric materials, creating a significant level of uncertainty in the field. Here we show that in nanoscale systems the ferroelectric state is fundamentally inseparable from the electrochemical state of the surface, leading to the emergence of a mixed electrochemical-ferroelectric state. We explore the nature, thermodynamics, and thickness evolution of such states, and demonstrate the experimental pathway to establish its presence. This analysis reconciles multiple prior studies, provides guidelines for studies of ferroelectric materials on the nanoscale, and establishes the design paradigm for new generations of ferroelectric-based devices.
Method for Developing Thin Film from Oxide or Silicate of Hafnium Nitride, Coordination Compound Used in Said Method, and Method for Producing Integrated Electronic Circuit
Phase Change Material Cell with Piezoelectric or Ferroelectric Stress Inducer Liner
Nano letters, Jan 9, 2016
Memristive devices, whose conductance depends on previous programming history, are of significant... more Memristive devices, whose conductance depends on previous programming history, are of significant interest for building nonvolatile memory and brain-inspired computing systems. Here, we report half-integer quantized conductance transitions G = (n/2) (2e(2)/h) for n = 1, 2, 3, etc., in Cu/SiO2/W memristive devices observed below 300 mV at room temperature. This is attributed to the nanoscale filamentary nature of Cu conductance pathways formed inside SiO2. Retention measurements also show spontaneous filament decay with quantized conductance levels. Numerical simulations shed light into the dynamics underlying the data retention loss mechanisms and provide new insights into the nanoscale physics of memristive devices and trade-offs involved in engineering them for computational applications.
Controlling ferroelectricity in dielectric films by process induced uniaxial strain
Engineering multiple threshold voltages in an integrated circuit
Dielectric Properties and Flat-Band Voltages of Doped HfO2
ECS Meeting Abstracts, 2010
ABSTRACT The control of high-symmetry phases of HfO2 can be achieved by cationic substitution for... more ABSTRACT The control of high-symmetry phases of HfO2 can be achieved by cationic substitution for Hf. The electrical properties of HfO2 cubic phase stabilized by addition of yttrium or magnesium are investigated. The introduction of moderate Y or Mg doping content (similar to 10-15 at.%) in HfO2 results in an enhancement of the dielectric constant. No degradation of the interface state density and leakage current is noticed. The flat-band voltage is shifted to positive voltages, similarly as it was observed for monoclinic and cubic pure HfO2 thin films. This result confirms that the contribution of the SiO2/high-kappa interface to the flat-band voltage depends on the structural high-kappa properties.
arXiv (Cornell University), Apr 27, 2022
Conductive bridge random access memory devices such as Cu/SiO2/W are promising candidates for app... more Conductive bridge random access memory devices such as Cu/SiO2/W are promising candidates for applications in neuromorphic computing due to their fast, low-voltage switching, multiple-conductance states, scalability, low off-current, and full compatibility with advanced Si CMOS technologies. The conductance states, which can be quantized, originate from the formation of a Cu filament in the SiO2 electrolyte due to cation-migration-based electrochemical processes. A major challenge related to the filamentary nature is the strong variability of the voltage required to switch the device to its conducting state. Here, based on a statistical analysis of more than hundred fifty Cu/SiO2/W devices, we point to the key role of the activation energy distribution for copper ion diffusion in the amorphous SiO2. The cycleto-cycle variability is modeled well when considering the theoretical energy landscape for Cu diffusion paths to grow the filament. Perspectives of this work point to developing strategies to narrow the distribution of activation energies in amorphous SiO2.
High k SrTiO3 Perovskite on Si/SiO2: CVD Growth, Interface Engineering and Dielectric Properties
ECS Meeting Abstracts, 2009
not Available.
Nature communications, Jan 29, 2024
Strain and Cation Stoichiometry in Epitaxial BaTiO3 Thin Films Grown on Silicon
International audienc
Epitaxial pyroelectric thin films on silicon for thermal energy harvesting
Growth parameters and tetragonality at the nanoscale of MBE epitaxial BaTiO3 films on Si
Thermal energy harvesting through epitaxial pyroelectric oxide films integrated on silicon
Integration of functional oxides on silicon for nanoelectronics and energy
Electro-optic modulation with functional oxides monolithically integrated on silicon
june 29-july 4 2014International audienceno abstrac
Epitaxial pyroelectric Pb(Zr,Ti)O3 thin films on silicon for thermal energy harvesting
11-15 mai 2015International audienceno abstrac
Pulsed-MOCVD Growth of Transition Metal Oxides
ECS Meeting Abstracts, 2005
not Available.
Toward van der Waals epitaxy of transferable ferroelectric barium titanate films via a graphene monolayer
Journal of Materials Chemistry C, 2020
Transferable highly (001)-oriented textured ferroelectric BaTiO3 thin films have been achieved on... more Transferable highly (001)-oriented textured ferroelectric BaTiO3 thin films have been achieved on a graphene monolayer for wearable devices like sensors and actuators for future “Internet of Things” era.
Correlation between the microwave surface resistance and the volumic fraction of a-axis grains in YBa2Cu3O7−x films
Physica C: Superconductivity, 1998
A quantitative study of the effect of a-axis grains (the a-axis is perpendicular to the substrate... more A quantitative study of the effect of a-axis grains (the a-axis is perpendicular to the substrate plane) on the microwave surface resistance in epitaxial YBa2Cu3O7−x films is reported. The films were grown by Metal Organic Chemical Vapor Deposition on MgO and LaAlO3 substrates. The fraction of a-axis grains %a has been varied in the range 0–70% by changing the oxygen partial pressure during the growth. A clear correlation between the surface resistance Rs(0.85Tc), measured at 87 GHz, and the volumic fraction %a is found. At variance, the residual surface resistance Rs(4.2 K) does not correlate to %a.
Nature Physics, 2017
Ferroelectricity on the nanoscale has been the subject of much fascination in condensed-matter ph... more Ferroelectricity on the nanoscale has been the subject of much fascination in condensed-matter physics for over half a century. In recent years, multiple reports claiming ferroelectricity in ultrathin ferroelectric films based on the formation of remnant polarization states, local electromechanical hysteresis loops, and pressure-induced switching were made. However, similar phenomena were reported for traditionally non-ferroelectric materials, creating a significant level of uncertainty in the field. Here we show that in nanoscale systems the ferroelectric state is fundamentally inseparable from the electrochemical state of the surface, leading to the emergence of a mixed electrochemical-ferroelectric state. We explore the nature, thermodynamics, and thickness evolution of such states, and demonstrate the experimental pathway to establish its presence. This analysis reconciles multiple prior studies, provides guidelines for studies of ferroelectric materials on the nanoscale, and establishes the design paradigm for new generations of ferroelectric-based devices.
Method for Developing Thin Film from Oxide or Silicate of Hafnium Nitride, Coordination Compound Used in Said Method, and Method for Producing Integrated Electronic Circuit
Phase Change Material Cell with Piezoelectric or Ferroelectric Stress Inducer Liner
Nano letters, Jan 9, 2016
Memristive devices, whose conductance depends on previous programming history, are of significant... more Memristive devices, whose conductance depends on previous programming history, are of significant interest for building nonvolatile memory and brain-inspired computing systems. Here, we report half-integer quantized conductance transitions G = (n/2) (2e(2)/h) for n = 1, 2, 3, etc., in Cu/SiO2/W memristive devices observed below 300 mV at room temperature. This is attributed to the nanoscale filamentary nature of Cu conductance pathways formed inside SiO2. Retention measurements also show spontaneous filament decay with quantized conductance levels. Numerical simulations shed light into the dynamics underlying the data retention loss mechanisms and provide new insights into the nanoscale physics of memristive devices and trade-offs involved in engineering them for computational applications.
Controlling ferroelectricity in dielectric films by process induced uniaxial strain
Engineering multiple threshold voltages in an integrated circuit