Philippe Djemia | Université Sorbonne Paris Nord / Sorbonne Paris Nord University (original) (raw)

Papers by Philippe Djemia

Research paper thumbnail of Identification of acoustic waves in ZnO materials by Brillouin light scattering for SAW device applications

Brillouin light scattering (BLS) was conducted on melt-grown ZnO bulk crystals and ZnO thin films... more Brillouin light scattering (BLS) was conducted on melt-grown ZnO bulk crystals and ZnO thin films grown by pulsed laser deposition. The bulk ZnO crystals presented both longitudinal and transverse bulk acoustic waves. Theoretical calculations agreed well with there being one piezoelectric longitudinal branch and two transverse branches. BLS measurements conducted on ZnO thin films also revealed Rayleigh surface acoustic waves (R-SAW) guided by only the surface of the layer and Sezawa modes, guided by the film thickness. Measurements were conducted for three incidence angles in order to investigate different SAW wave numbers. Higher frequency features were identified as being related to a new class of guided longitudinal (LG) SAW modes which are not usually detected for ZnO thin films. The LG-SAW modes were observed for two incidence angles (θ=45° and 55°) corresponding to frequencies of 17.88 and 20.75 GHz, respectively. BLS measurements enable us to estimate the LG-SAW velocity as 6500 m/s. This value is three times higher than that of the currently used R-SAW. Theoretical simulations were coherent with the presence of LG modes in the ZnO layers. Such LG-SAW modes are promising for the development of novel, higher-speed SAW devices operating in the GHz-band and which could be readily incorporated in Si-based integrated circuitry.

Research paper thumbnail of Identification of acoustic waves in ZnO materials by Brillouin light scattering for SAW device applications

Brillouin light scattering (BLS) was conducted on melt-grown ZnO bulk crystals and ZnO thin films... more Brillouin light scattering (BLS) was conducted on melt-grown ZnO bulk crystals and ZnO thin films grown by pulsed laser deposition. The bulk ZnO crystals presented both longitudinal and transverse bulk acoustic waves. Theoretical calculations agreed well with there being one piezoelectric longitudinal branch and two transverse branches. BLS measurements conducted on ZnO thin films also revealed Rayleigh surface acoustic waves (R-SAW) guided by only the surface of the layer and Sezawa modes, guided by the film thickness. Measurements were conducted for three incidence angles in order to investigate different SAW wave numbers. Higher frequency features were identified as being related to a new class of guided longitudinal (LG) SAW modes which are not usually detected for ZnO thin films. The LG-SAW modes were observed for two incidence angles (θ=45° and 55°) corresponding to frequencies of 17.88 and 20.75 GHz, respectively. BLS measurements enable us to estimate the LG-SAW velocity as 6500 m/s. This value is three times higher than that of the currently used R-SAW. Theoretical simulations were coherent with the presence of LG modes in the ZnO layers. Such LG-SAW modes are promising for the development of novel, higher-speed SAW devices operating in the GHz-band and which could be readily incorporated in Si-based integrated circuitry.

Research paper thumbnail of Nondestructive evaluation of micrometric diamond films with an interferometric picosecond ultrasonics technique

Journal of Applied Physics, 2004

Research paper thumbnail of Elastic properties of ultrathin permalloy/alumina multilayer films using picosecond ultrasonics and Brillouin light scattering

Research paper thumbnail of X-ray strain analysis in thin films enhanced by 2D detection

EPJ Web of Conferences, 2010

Research paper thumbnail of A means for the study of elastic properties of layers and thin multilayers: Brillouin spectroscopy

Research paper thumbnail of Supplementary materials

Research paper thumbnail of X-ray strain analysis in thin films enhanced by 2D detection

The European Physical Journal Conferences

Performing a complete in-situ strain measurement of polycrystalline thin films using X-ray diffra... more Performing a complete in-situ strain measurement of polycrystalline thin films using X-ray diffraction is time consuming with most standard diffraction beamlines at synchrotron facilities and not realistic with laboratory diffractometers. Two dimensional detection is shown to enable relatively fast and reliable X-ray strain measurements during continuous in-situ tensile testing of metallic films deposited on polyimide substrates. We show in this paper the advantages to perform this kind of measurements as compared to those with punctual detection.

Research paper thumbnail of Alloying effects on the structure and elastic properties of hard coatings based on ternary transition metal (M=Ti, Zr or Ta) nitrides

Surface and Coatings Technology, 2014

ABSTRACT Multicomponent alloying is an effective design route to increase toughening in hard nitr... more ABSTRACT Multicomponent alloying is an effective design route to increase toughening in hard nitride-based coatings. We provide density functional theory calculations and experimental assessment of the elastic properties of a series of ternary transition metal nitride coatings. M11 − xM2xN films (M1, M2 = Ti, Zr, Ta) were elaborated by reactive magnetron co-sputtering. The structural (texture and microstructure) and growth morphology evolution as a function of film thickness and chemical composition were investigated by X-ray diffraction, X-ray reflectivity, electron probe microanalysis and scanning electron microscopy. The effective elastic constants, C33 and C44, were obtained from longitudinal and transverse sound velocity measurements, using picosecond ultrasonics (PU) and Brillouin light scattering (BLS), respectively. We employ Blackman diagram, as well as Pugh and Pettifor criteria, to derive trends in elastic anisotropy, bonding character and brittleness vs. ductility. The influence of microstructure and preferred orientation on the elastic response of polycrystalline films is discussed. For Ta-rich TiTaN and TaZrN systems, the formation of a nanocomposite system consisting of a mixture of cubic and hexagonal phases has a beneficial contribution to toughening.

Research paper thumbnail of X-ray strain analysis in thin films enhanced by 2D detection

EPJ Web of Conferences, 2010

Research paper thumbnail of Study of spin waves in magnetic thin films submitted to external mechanical stresses

EPJ Web of Conferences, 2010

Research paper thumbnail of Virtual crystal approximation revisited: Application to dielectric and piezoelectric properties of perovskites

Research paper thumbnail of REPONSE HAUTE FREQUENCE DE PLOTS SUPPORTANT UNE STRUCTURE MAGNETIQUE EN RUBANS

Research paper thumbnail of Tool for studying the elastic properties of thin layers and multilayers: Brillouin spectroscopy

Research paper thumbnail of Surface and bulk characterizations of CN sub x thin films made by r. f. magnetron sputtering

Research paper thumbnail of Interfacial alloying induced shear elastic softening in (111) Ni/(110) Mo multilayers

Research paper thumbnail of Magnonic and phononic properties of inverse opal structures

Research paper thumbnail of Weak stripe domains vibrations description using Thiele equation

Research paper thumbnail of DIFFUSION BRILLOUIN DANS DES COUCHES ET MULTICOUCHES ULTRAMINCES: INFLUENCES DE LA MICROSTRUCTURE ET DES INTERFACES DANS QUELQUES SYSTÈMES REPRÉSENTATIFS(CUxMO 1 -x,  MO/NI, PERMALLOY/ALUMINE, CO/CU)

Research paper thumbnail of Un outil pour l'étude des propriétés élastiques des couches et multicouches minces: la spectroscopie Brillouin

ABSTRACT Some general features concerning inelastic light scattering by hypersonic waves are expo... more ABSTRACT Some general features concerning inelastic light scattering by hypersonic waves are exposed and it is shown that Brillouin spectroscopy can be fruitfully applied in order to study the elastic properties of thin and ultrathin films as well as of multilayers and superlattices. A brief presentation of the various kinds of surface waves and of the mechanisms which monitor the scattering by these excitations is provided. Examples concerning transparent and opaque structures are given. The important influence of the interfaces is pointed out.

Research paper thumbnail of Identification of acoustic waves in ZnO materials by Brillouin light scattering for SAW device applications

Brillouin light scattering (BLS) was conducted on melt-grown ZnO bulk crystals and ZnO thin films... more Brillouin light scattering (BLS) was conducted on melt-grown ZnO bulk crystals and ZnO thin films grown by pulsed laser deposition. The bulk ZnO crystals presented both longitudinal and transverse bulk acoustic waves. Theoretical calculations agreed well with there being one piezoelectric longitudinal branch and two transverse branches. BLS measurements conducted on ZnO thin films also revealed Rayleigh surface acoustic waves (R-SAW) guided by only the surface of the layer and Sezawa modes, guided by the film thickness. Measurements were conducted for three incidence angles in order to investigate different SAW wave numbers. Higher frequency features were identified as being related to a new class of guided longitudinal (LG) SAW modes which are not usually detected for ZnO thin films. The LG-SAW modes were observed for two incidence angles (θ=45° and 55°) corresponding to frequencies of 17.88 and 20.75 GHz, respectively. BLS measurements enable us to estimate the LG-SAW velocity as 6500 m/s. This value is three times higher than that of the currently used R-SAW. Theoretical simulations were coherent with the presence of LG modes in the ZnO layers. Such LG-SAW modes are promising for the development of novel, higher-speed SAW devices operating in the GHz-band and which could be readily incorporated in Si-based integrated circuitry.

Research paper thumbnail of Identification of acoustic waves in ZnO materials by Brillouin light scattering for SAW device applications

Brillouin light scattering (BLS) was conducted on melt-grown ZnO bulk crystals and ZnO thin films... more Brillouin light scattering (BLS) was conducted on melt-grown ZnO bulk crystals and ZnO thin films grown by pulsed laser deposition. The bulk ZnO crystals presented both longitudinal and transverse bulk acoustic waves. Theoretical calculations agreed well with there being one piezoelectric longitudinal branch and two transverse branches. BLS measurements conducted on ZnO thin films also revealed Rayleigh surface acoustic waves (R-SAW) guided by only the surface of the layer and Sezawa modes, guided by the film thickness. Measurements were conducted for three incidence angles in order to investigate different SAW wave numbers. Higher frequency features were identified as being related to a new class of guided longitudinal (LG) SAW modes which are not usually detected for ZnO thin films. The LG-SAW modes were observed for two incidence angles (θ=45° and 55°) corresponding to frequencies of 17.88 and 20.75 GHz, respectively. BLS measurements enable us to estimate the LG-SAW velocity as 6500 m/s. This value is three times higher than that of the currently used R-SAW. Theoretical simulations were coherent with the presence of LG modes in the ZnO layers. Such LG-SAW modes are promising for the development of novel, higher-speed SAW devices operating in the GHz-band and which could be readily incorporated in Si-based integrated circuitry.

Research paper thumbnail of Nondestructive evaluation of micrometric diamond films with an interferometric picosecond ultrasonics technique

Journal of Applied Physics, 2004

Research paper thumbnail of Elastic properties of ultrathin permalloy/alumina multilayer films using picosecond ultrasonics and Brillouin light scattering

Research paper thumbnail of X-ray strain analysis in thin films enhanced by 2D detection

EPJ Web of Conferences, 2010

Research paper thumbnail of A means for the study of elastic properties of layers and thin multilayers: Brillouin spectroscopy

Research paper thumbnail of Supplementary materials

Research paper thumbnail of X-ray strain analysis in thin films enhanced by 2D detection

The European Physical Journal Conferences

Performing a complete in-situ strain measurement of polycrystalline thin films using X-ray diffra... more Performing a complete in-situ strain measurement of polycrystalline thin films using X-ray diffraction is time consuming with most standard diffraction beamlines at synchrotron facilities and not realistic with laboratory diffractometers. Two dimensional detection is shown to enable relatively fast and reliable X-ray strain measurements during continuous in-situ tensile testing of metallic films deposited on polyimide substrates. We show in this paper the advantages to perform this kind of measurements as compared to those with punctual detection.

Research paper thumbnail of Alloying effects on the structure and elastic properties of hard coatings based on ternary transition metal (M=Ti, Zr or Ta) nitrides

Surface and Coatings Technology, 2014

ABSTRACT Multicomponent alloying is an effective design route to increase toughening in hard nitr... more ABSTRACT Multicomponent alloying is an effective design route to increase toughening in hard nitride-based coatings. We provide density functional theory calculations and experimental assessment of the elastic properties of a series of ternary transition metal nitride coatings. M11 − xM2xN films (M1, M2 = Ti, Zr, Ta) were elaborated by reactive magnetron co-sputtering. The structural (texture and microstructure) and growth morphology evolution as a function of film thickness and chemical composition were investigated by X-ray diffraction, X-ray reflectivity, electron probe microanalysis and scanning electron microscopy. The effective elastic constants, C33 and C44, were obtained from longitudinal and transverse sound velocity measurements, using picosecond ultrasonics (PU) and Brillouin light scattering (BLS), respectively. We employ Blackman diagram, as well as Pugh and Pettifor criteria, to derive trends in elastic anisotropy, bonding character and brittleness vs. ductility. The influence of microstructure and preferred orientation on the elastic response of polycrystalline films is discussed. For Ta-rich TiTaN and TaZrN systems, the formation of a nanocomposite system consisting of a mixture of cubic and hexagonal phases has a beneficial contribution to toughening.

Research paper thumbnail of X-ray strain analysis in thin films enhanced by 2D detection

EPJ Web of Conferences, 2010

Research paper thumbnail of Study of spin waves in magnetic thin films submitted to external mechanical stresses

EPJ Web of Conferences, 2010

Research paper thumbnail of Virtual crystal approximation revisited: Application to dielectric and piezoelectric properties of perovskites

Research paper thumbnail of REPONSE HAUTE FREQUENCE DE PLOTS SUPPORTANT UNE STRUCTURE MAGNETIQUE EN RUBANS

Research paper thumbnail of Tool for studying the elastic properties of thin layers and multilayers: Brillouin spectroscopy

Research paper thumbnail of Surface and bulk characterizations of CN sub x thin films made by r. f. magnetron sputtering

Research paper thumbnail of Interfacial alloying induced shear elastic softening in (111) Ni/(110) Mo multilayers

Research paper thumbnail of Magnonic and phononic properties of inverse opal structures

Research paper thumbnail of Weak stripe domains vibrations description using Thiele equation

Research paper thumbnail of DIFFUSION BRILLOUIN DANS DES COUCHES ET MULTICOUCHES ULTRAMINCES: INFLUENCES DE LA MICROSTRUCTURE ET DES INTERFACES DANS QUELQUES SYSTÈMES REPRÉSENTATIFS(CUxMO 1 -x,  MO/NI, PERMALLOY/ALUMINE, CO/CU)

Research paper thumbnail of Un outil pour l'étude des propriétés élastiques des couches et multicouches minces: la spectroscopie Brillouin

ABSTRACT Some general features concerning inelastic light scattering by hypersonic waves are expo... more ABSTRACT Some general features concerning inelastic light scattering by hypersonic waves are exposed and it is shown that Brillouin spectroscopy can be fruitfully applied in order to study the elastic properties of thin and ultrathin films as well as of multilayers and superlattices. A brief presentation of the various kinds of surface waves and of the mechanisms which monitor the scattering by these excitations is provided. Examples concerning transparent and opaque structures are given. The important influence of the interfaces is pointed out.