Frédéric Wyczisk - Academia.edu (original) (raw)

Papers by Frédéric Wyczisk

Applied Surface Science, 2011

The diffusion of Mg in pulsed laser deposited K(Ta 0.65 Nb 0.35)O 3 thin films epitaxially grown ... more The diffusion of Mg in pulsed laser deposited K(Ta 0.65 Nb 0.35)O 3 thin films epitaxially grown on (1 0 0) MgO single crystal substrate were investigated by Auger electron spectroscopy (AES). A diffusion of Mg from the substrate into the whole thickness (400 nm) of the as-deposited K(Ta 0.65 Nb 0.35)O 3 films was observed with an accumulation of Mg at the surface. Ex situ post-annealing (750 • C/2 h) has led to a homogeneous distribution of Mg in all the ferroelectric coating. This strong reaction between film and substrate promotes a doping effect, responsible for the reduction of K(Ta 0.65 Nb 0.35)O 3 dielectric losses in comparison with films grown on other substrates.

Journal of Applied Physics, 1983

Plasma enhanced chemically-vapor-deposited silicon-rich oxides (200 Å and 500 Å in thickness) of ... more Plasma enhanced chemically-vapor-deposited silicon-rich oxides (200 Å and 500 Å in thickness) of various excess silicon content were deposited onto thermal silicon dioxide (SiO2) layers (103, 207, and 530 Å in thickness) grown on a p-type silicon (Si) substrate. The dielectric constant, electron injection efficiency, current-voltage (I-V) reproducibility, and breakdown property of these composite structures were examined. The dielectric constants of Si-rich oxide were observed to increase with Si content from 3.8 for films deposited at a gas phase ratio (R0) of the concentration of nitrous oxide (N2O) to silane (SiH4) of 150 to ∼10 for films deposited with R0=0. The Si-rich oxides with R0≤5 were found to work as electron injectors. The average oxide field needed to induce a current of 4.8×10−7 A/cm2 through the SiO2 (530 Å in thickness) decreased about 40% in magnitude by adding a Si-rich oxide layer with the optimized R0(=1) compared to that of a control sample which had no Si-rich...

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena, 2009

This article presents the results of microstructural, compositional, and optical characterization... more This article presents the results of microstructural, compositional, and optical characterization of GaN films grown on ZnO buffered c-sapphire substrates. Transmission electron microscopy showed epitaxy between the GaN and the ZnO, no degradation of the ZnO buffer layer, and no evidence of any interfacial compounds. Secondary ion mass spectroscopy revealed negligible Zn signal in the GaN layer away from the GaN∕ZnO interface. After chemical removal of the ZnO, room temperature (RT) cathodoluminescence spectra had a single main peak centered at ∼368nm (∼3.37eV), which was indexed as near-band-edge (NBE) emission from the GaN layer. There was no evidence of the ZnO NBE peak, centered at ∼379nm (∼3.28eV), which had been observed in RT photoluminescence spectra prior to removal of the ZnO.

Physical Review B, 2007

A comparative study of La x Bi 1−x MnO 3 thin films grown on SrTiO 3 substrates is reported. It i... more A comparative study of La x Bi 1−x MnO 3 thin films grown on SrTiO 3 substrates is reported. It is shown that these films grow epitaxially in a narrow pressure-temperature range. A detailed structural and compositional characterization of the films is performed within the growth window. The structure and the magnetization of this system are investigated. We find a clear correlation between the magnetization and the unit-cell volume that we ascribe to Bi deficiency and the resultant introduction of a mixed valence on the Mn ions. On these grounds, we show that the reduced magnetization of La x Bi 1−x MnO 3 thin films compared to the bulk can be explained quantitatively by a simple model, taking into account the deviation from nominal composition and the Goodenough-Kanamori-Anderson rules of magnetic interactions.

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena, 1992

It is shown by reflection high-energy electron diffraction that the temperature at which As and S... more It is shown by reflection high-energy electron diffraction that the temperature at which As and Si interact is a key factor in surface reconstruction: at low (TS = 400 °C) and high (TS= 600–700 °C) substrate temperature, and at As4 pressure ∼ 10−5 Torr, the dangling bonds of arsenic are, respectively, perpendicular or parallel to the step edges of the vicinal surface. Photoelectron diffraction shows that, from the very first steps of GaAs molecular-beam epitaxial growth on such surfaces, the GaAs lattice (i) exhibits two orientations determined by As initial orientation and related by a 90° rotation, (ii) is without antiphase domains within the sensitivity limit of the method.

Surface Science, 1985

... etched at TH = 25 (': [A)just after etching, (B) after 6 min air exposure, (C) 30 min ai... more ... etched at TH = 25 (': [A)just after etching, (B) after 6 min air exposure, (C) 30 min air exposure, (I)) 90 min air exposure, (F,) 160 rain exposure. ... the unit mesh of GaAs (d = 2.825 A,), h is the mean free path of As(3d) electrons which is equal to 25 .~, according to Seah and Dench ...

MRS Proceedings, 2015

ABSTRACTThe optimization of the figure of merit of thermoelectric materials requires the simultan... more ABSTRACTThe optimization of the figure of merit of thermoelectric materials requires the simultaneous control of the material composition and microstructure. Assembly of nanoparticles obtained by a solution route is an attractive bulk fabrication method because size and shape of the nanoparticles can be tuned by variation of the synthesis conditions. Recently, new synthetic pathways were reported among which reducing agent assisted, surfactant free processes. We report here the evaluation of this method for the synthesis of Bi2TexSe3-xalloyed nanoparticles with varying selenium concentrations. X-ray diffraction studies conducted on powder and pellet samples show that two alloyed phases are present in the sample even at low selenium content. The careful study of the position of the diffraction peaks as function of the formulation shows that this behaviour could arise from the difference in reactivity of selenium and tellurium. Moreover, the electrical conductivity of the samples is s...

MRS Proceedings, 1987

ABSTRACTWe have studied the influence of different GaAs surface treatments on the chemical compos... more ABSTRACTWe have studied the influence of different GaAs surface treatments on the chemical composition and electrical behavior of the Si 3 N4 -GaAs interface, where Si 3 N4 was plasma enhanced chemical vapor deposited (PECVD) onto the treated GaAs(100) substrate. The chemistry of the resulting interface has been studied by X-ray photoelectron spectroscopy (XPS). It has been demonstrated that the chemical composition of the Si 3 N4-GaAs interface is drastically dependent on GaAs surface pretreatment and r.f. plasma excitation frequency. Output-input powers characteristics have been measured on chemically treated planar MESFET after Si3N4. passivation.

physica status solidi (a), 2003

Materials Science Forum, 2000

The 17th Annual Meeting of the IEEELasers and Electro-Optics Society, 2004. LEOS 2004.

Carbon nanotubes are grown, as opposed to being lithographically defined, with diameters between ... more Carbon nanotubes are grown, as opposed to being lithographically defined, with diameters between 1.3 - 100 nm and lengths of a few micrometers. They have the 'natural' geometry required for field emission. The challenge is to develop a technology which allows the CNTs to be incorporated into a field emission cathode back plane together with the required gating and contact

J. Mater. Chem. A, 2014

This work reports the influence of a Cr layer in boosting the thermoelectric properties of a non-... more This work reports the influence of a Cr layer in boosting the thermoelectric properties of a non-toxic and abundant thermoelectric material, V2O5, deposited as a thin film by thermal evaporation and annealed at 500 °C, reachingZT> 0.1.

Semiconductor Science and Technology, 1991

ABSTRACT

Physica Scripta, 1990

ABSTRACT

Nano Letters, 2013

It has been claimed that graphene growth on copper by chemical vapor deposition is dominated by c... more It has been claimed that graphene growth on copper by chemical vapor deposition is dominated by crystallization from the surface initially supersaturated with carbon adatoms, which implies that the growth is independent of hydrocarbon addition after the nucleation phase. Here, we present an alternative growth model based on our observations that oppose this claim. Our Gompertzian sigmoidal growth kinetics and secondary nucleation behavior support the postulate that the growth can be controlled by adsorption-desorption dynamics and the dispersive kinetic processes of catalytic dissociation and dehydrogenation of carbon precursors on copper.

Microelectronics Reliability, 2009

Ti/Al/Ni/Au stack is widely used to form ohmic contact on GaN based semiconductor material. Long ... more Ti/Al/Ni/Au stack is widely used to form ohmic contact on GaN based semiconductor material. Long term thermal storage tests conducted to assess AlGaN/GaN HEMT technology have shown a dramatic degradation of this metal when stored more than 100 h at temperatures above 340°C. The first evidence of degradation is the increase of resistance and the surface morphology evolution leading passivation film to crack. AES and EDS analyses have demonstrated that Ga out-diffusion and Au inter-diffusion are the root causes of this degradation. Cross sections outlined voids occurrence.

Microelectronic Engineering, 2001

Schottky contacts are investigated on n-type 4H-SiC by electrical measurements and microstructura... more Schottky contacts are investigated on n-type 4H-SiC by electrical measurements and microstructural analyses to understand the behaviour of such a barrier. Titanium and tungsten were deposited after RCA cleaning as surface preparation of SiC. Electrical characterisation shows that the Fermi level is partially pinned by interfacial surface states attributed to an interfacial layer between the metal and the SiC. This

Journal of Electronic Materials, 1999

Journal of Electron Spectroscopy and Related Phenomena, 1987

Electron scattering and diffraction in X-ray photoemission spectroscopy (XPS) have been used to c... more Electron scattering and diffraction in X-ray photoemission spectroscopy (XPS) have been used to characterize GaAs(001) and InP(001) chemically etched surfaces. 6a(3d),As(3d), In(4d) and P(2p) photoelectrons have been observed as a function of polar angles for the two [1-103 and (110] azimuths For kinetic energy range of these photoelectrons the experimental results have been correctly predicted by the single-scattering cluster model with spherical-wave corrections. The problems of quantitative measurements in XPS have been discussed in relation with the diffraction phenomena.

Journal of Applied Physics, 1993

The effect of the ultrathin interfacial layer of silicon nitride deposited by remote plasma-enhan... more The effect of the ultrathin interfacial layer of silicon nitride deposited by remote plasma-enhanced chemical vapor deposition technique on the Schottky barrier characteristics of Au/n-GaAs contacts is investigated. The changes of both capacitance-voltage and current-voltage characteristics, in dependence on the interfacial layer thicknesses are discussed and explained on the basis of the surface passivation. The influence of thermal annealing on the structure and electrical properties is also presented. In contrast to the very poor stability of the electrical characteristics of reference Au/GaAs contacts, structures with silicon nitride interfacial layers show much improved thermal stability with the minimum ideality factor for the silicon nitride interfacial layer being 9 Å thick and annealed at 450 °C. The effect of silicon nitride interlayer as a diffusion barrier is confirmed by Auger electron spectroscopy analysis of both reference and silicon nitride containing structures.

Applied Surface Science, 2011

The diffusion of Mg in pulsed laser deposited K(Ta 0.65 Nb 0.35)O 3 thin films epitaxially grown ... more The diffusion of Mg in pulsed laser deposited K(Ta 0.65 Nb 0.35)O 3 thin films epitaxially grown on (1 0 0) MgO single crystal substrate were investigated by Auger electron spectroscopy (AES). A diffusion of Mg from the substrate into the whole thickness (400 nm) of the as-deposited K(Ta 0.65 Nb 0.35)O 3 films was observed with an accumulation of Mg at the surface. Ex situ post-annealing (750 • C/2 h) has led to a homogeneous distribution of Mg in all the ferroelectric coating. This strong reaction between film and substrate promotes a doping effect, responsible for the reduction of K(Ta 0.65 Nb 0.35)O 3 dielectric losses in comparison with films grown on other substrates.

Journal of Applied Physics, 1983

Plasma enhanced chemically-vapor-deposited silicon-rich oxides (200 Å and 500 Å in thickness) of ... more Plasma enhanced chemically-vapor-deposited silicon-rich oxides (200 Å and 500 Å in thickness) of various excess silicon content were deposited onto thermal silicon dioxide (SiO2) layers (103, 207, and 530 Å in thickness) grown on a p-type silicon (Si) substrate. The dielectric constant, electron injection efficiency, current-voltage (I-V) reproducibility, and breakdown property of these composite structures were examined. The dielectric constants of Si-rich oxide were observed to increase with Si content from 3.8 for films deposited at a gas phase ratio (R0) of the concentration of nitrous oxide (N2O) to silane (SiH4) of 150 to ∼10 for films deposited with R0=0. The Si-rich oxides with R0≤5 were found to work as electron injectors. The average oxide field needed to induce a current of 4.8×10−7 A/cm2 through the SiO2 (530 Å in thickness) decreased about 40% in magnitude by adding a Si-rich oxide layer with the optimized R0(=1) compared to that of a control sample which had no Si-rich...

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena, 2009

This article presents the results of microstructural, compositional, and optical characterization... more This article presents the results of microstructural, compositional, and optical characterization of GaN films grown on ZnO buffered c-sapphire substrates. Transmission electron microscopy showed epitaxy between the GaN and the ZnO, no degradation of the ZnO buffer layer, and no evidence of any interfacial compounds. Secondary ion mass spectroscopy revealed negligible Zn signal in the GaN layer away from the GaN∕ZnO interface. After chemical removal of the ZnO, room temperature (RT) cathodoluminescence spectra had a single main peak centered at ∼368nm (∼3.37eV), which was indexed as near-band-edge (NBE) emission from the GaN layer. There was no evidence of the ZnO NBE peak, centered at ∼379nm (∼3.28eV), which had been observed in RT photoluminescence spectra prior to removal of the ZnO.

Physical Review B, 2007

A comparative study of La x Bi 1−x MnO 3 thin films grown on SrTiO 3 substrates is reported. It i... more A comparative study of La x Bi 1−x MnO 3 thin films grown on SrTiO 3 substrates is reported. It is shown that these films grow epitaxially in a narrow pressure-temperature range. A detailed structural and compositional characterization of the films is performed within the growth window. The structure and the magnetization of this system are investigated. We find a clear correlation between the magnetization and the unit-cell volume that we ascribe to Bi deficiency and the resultant introduction of a mixed valence on the Mn ions. On these grounds, we show that the reduced magnetization of La x Bi 1−x MnO 3 thin films compared to the bulk can be explained quantitatively by a simple model, taking into account the deviation from nominal composition and the Goodenough-Kanamori-Anderson rules of magnetic interactions.

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena, 1992

It is shown by reflection high-energy electron diffraction that the temperature at which As and S... more It is shown by reflection high-energy electron diffraction that the temperature at which As and Si interact is a key factor in surface reconstruction: at low (TS = 400 °C) and high (TS= 600–700 °C) substrate temperature, and at As4 pressure ∼ 10−5 Torr, the dangling bonds of arsenic are, respectively, perpendicular or parallel to the step edges of the vicinal surface. Photoelectron diffraction shows that, from the very first steps of GaAs molecular-beam epitaxial growth on such surfaces, the GaAs lattice (i) exhibits two orientations determined by As initial orientation and related by a 90° rotation, (ii) is without antiphase domains within the sensitivity limit of the method.

Surface Science, 1985

... etched at TH = 25 (': [A)just after etching, (B) after 6 min air exposure, (C) 30 min ai... more ... etched at TH = 25 (': [A)just after etching, (B) after 6 min air exposure, (C) 30 min air exposure, (I)) 90 min air exposure, (F,) 160 rain exposure. ... the unit mesh of GaAs (d = 2.825 A,), h is the mean free path of As(3d) electrons which is equal to 25 .~, according to Seah and Dench ...

MRS Proceedings, 2015

ABSTRACTThe optimization of the figure of merit of thermoelectric materials requires the simultan... more ABSTRACTThe optimization of the figure of merit of thermoelectric materials requires the simultaneous control of the material composition and microstructure. Assembly of nanoparticles obtained by a solution route is an attractive bulk fabrication method because size and shape of the nanoparticles can be tuned by variation of the synthesis conditions. Recently, new synthetic pathways were reported among which reducing agent assisted, surfactant free processes. We report here the evaluation of this method for the synthesis of Bi2TexSe3-xalloyed nanoparticles with varying selenium concentrations. X-ray diffraction studies conducted on powder and pellet samples show that two alloyed phases are present in the sample even at low selenium content. The careful study of the position of the diffraction peaks as function of the formulation shows that this behaviour could arise from the difference in reactivity of selenium and tellurium. Moreover, the electrical conductivity of the samples is s...

MRS Proceedings, 1987

ABSTRACTWe have studied the influence of different GaAs surface treatments on the chemical compos... more ABSTRACTWe have studied the influence of different GaAs surface treatments on the chemical composition and electrical behavior of the Si 3 N4 -GaAs interface, where Si 3 N4 was plasma enhanced chemical vapor deposited (PECVD) onto the treated GaAs(100) substrate. The chemistry of the resulting interface has been studied by X-ray photoelectron spectroscopy (XPS). It has been demonstrated that the chemical composition of the Si 3 N4-GaAs interface is drastically dependent on GaAs surface pretreatment and r.f. plasma excitation frequency. Output-input powers characteristics have been measured on chemically treated planar MESFET after Si3N4. passivation.

physica status solidi (a), 2003

Materials Science Forum, 2000

The 17th Annual Meeting of the IEEELasers and Electro-Optics Society, 2004. LEOS 2004.

Carbon nanotubes are grown, as opposed to being lithographically defined, with diameters between ... more Carbon nanotubes are grown, as opposed to being lithographically defined, with diameters between 1.3 - 100 nm and lengths of a few micrometers. They have the 'natural' geometry required for field emission. The challenge is to develop a technology which allows the CNTs to be incorporated into a field emission cathode back plane together with the required gating and contact

J. Mater. Chem. A, 2014

This work reports the influence of a Cr layer in boosting the thermoelectric properties of a non-... more This work reports the influence of a Cr layer in boosting the thermoelectric properties of a non-toxic and abundant thermoelectric material, V2O5, deposited as a thin film by thermal evaporation and annealed at 500 °C, reachingZT> 0.1.

Semiconductor Science and Technology, 1991

ABSTRACT

Physica Scripta, 1990

ABSTRACT

Nano Letters, 2013

It has been claimed that graphene growth on copper by chemical vapor deposition is dominated by c... more It has been claimed that graphene growth on copper by chemical vapor deposition is dominated by crystallization from the surface initially supersaturated with carbon adatoms, which implies that the growth is independent of hydrocarbon addition after the nucleation phase. Here, we present an alternative growth model based on our observations that oppose this claim. Our Gompertzian sigmoidal growth kinetics and secondary nucleation behavior support the postulate that the growth can be controlled by adsorption-desorption dynamics and the dispersive kinetic processes of catalytic dissociation and dehydrogenation of carbon precursors on copper.

Microelectronics Reliability, 2009

Ti/Al/Ni/Au stack is widely used to form ohmic contact on GaN based semiconductor material. Long ... more Ti/Al/Ni/Au stack is widely used to form ohmic contact on GaN based semiconductor material. Long term thermal storage tests conducted to assess AlGaN/GaN HEMT technology have shown a dramatic degradation of this metal when stored more than 100 h at temperatures above 340°C. The first evidence of degradation is the increase of resistance and the surface morphology evolution leading passivation film to crack. AES and EDS analyses have demonstrated that Ga out-diffusion and Au inter-diffusion are the root causes of this degradation. Cross sections outlined voids occurrence.

Microelectronic Engineering, 2001

Schottky contacts are investigated on n-type 4H-SiC by electrical measurements and microstructura... more Schottky contacts are investigated on n-type 4H-SiC by electrical measurements and microstructural analyses to understand the behaviour of such a barrier. Titanium and tungsten were deposited after RCA cleaning as surface preparation of SiC. Electrical characterisation shows that the Fermi level is partially pinned by interfacial surface states attributed to an interfacial layer between the metal and the SiC. This

Journal of Electronic Materials, 1999

Journal of Electron Spectroscopy and Related Phenomena, 1987

Electron scattering and diffraction in X-ray photoemission spectroscopy (XPS) have been used to c... more Electron scattering and diffraction in X-ray photoemission spectroscopy (XPS) have been used to characterize GaAs(001) and InP(001) chemically etched surfaces. 6a(3d),As(3d), In(4d) and P(2p) photoelectrons have been observed as a function of polar angles for the two [1-103 and (110] azimuths For kinetic energy range of these photoelectrons the experimental results have been correctly predicted by the single-scattering cluster model with spherical-wave corrections. The problems of quantitative measurements in XPS have been discussed in relation with the diffraction phenomena.

Journal of Applied Physics, 1993

The effect of the ultrathin interfacial layer of silicon nitride deposited by remote plasma-enhan... more The effect of the ultrathin interfacial layer of silicon nitride deposited by remote plasma-enhanced chemical vapor deposition technique on the Schottky barrier characteristics of Au/n-GaAs contacts is investigated. The changes of both capacitance-voltage and current-voltage characteristics, in dependence on the interfacial layer thicknesses are discussed and explained on the basis of the surface passivation. The influence of thermal annealing on the structure and electrical properties is also presented. In contrast to the very poor stability of the electrical characteristics of reference Au/GaAs contacts, structures with silicon nitride interfacial layers show much improved thermal stability with the minimum ideality factor for the silicon nitride interfacial layer being 9 Å thick and annealed at 450 °C. The effect of silicon nitride interlayer as a diffusion barrier is confirmed by Auger electron spectroscopy analysis of both reference and silicon nitride containing structures.