Y. Mlik | Ecole Nationale d'Ingénieurs de Sfax (ENIS) (original) (raw)
Papers by Y. Mlik
Journal of Physics C: Solid State Physics, 1983
Acta Crystallographica Section A Foundations of Crystallography, 1984
physica status solidi (b), 1984
ABSTRACT
Canadian Journal of Chemistry, 1984
Journal of Physics C Solid State Physics
The Raman spectra of the isomorphous compounds (CH&NMnCls, (CDs)dNMnC13 and (CH3)4NCdC13 in the r... more The Raman spectra of the isomorphous compounds (CH&NMnCls, (CDs)dNMnC13 and (CH3)4NCdC13 in the regions of the lattice vibrations and of the internal modes of the tetramethylammonium skeleton are reinvestigated at temperatures ranging from 300 to 25 K. On the basis of the hypothesis that group-to-subgroup relations exist between the high-and low-temperature phases of these compounds, a group theoretical analysis of possiblephase transitions has been made. Thecompatibility between the observed spectra and those predicted by group theory leads to the conclusion that for the cadmium compound the phase sequence could be
Journal of Physics C: Solid State Physics, 1982
The Raman spectra of the isomorphous compounds (CH&NMnCls, (CDs)dNMnC13 and (CH3)4NCdC13 in the r... more The Raman spectra of the isomorphous compounds (CH&NMnCls, (CDs)dNMnC13 and (CH3)4NCdC13 in the regions of the lattice vibrations and of the internal modes of the tetramethylammonium skeleton are reinvestigated at temperatures ranging from 300 to 25 K. On the basis of the hypothesis that group-to-subgroup relations exist between the high-and low-temperature phases of these compounds, a group theoretical analysis of possiblephase transitions has been made. Thecompatibility between the observed spectra and those predicted by group theory leads to the conclusion that for the cadmium compound the phase sequence could be
Physica Status Solidi (a), 1979
Physica Status Solidi (a), 1989
Physica Status Solidi (a), 1980
physica status solidi (b), 2003
In this paper we report electron beam induced current (EBIC) measurements on Schottky diodes on u... more In this paper we report electron beam induced current (EBIC) measurements on Schottky diodes on undoped GaN samples grown by the metal organic vapor phase epitaxy method on porous silicon substrates. A 2D simulation model was applied to perform the theoretical EBIC profiles and to compare with the experimental one. A minority carrier diffusion length (L) for holes of 0.72
physica status solidi (b), 1987
ABSTRACT
physica status solidi (a), 2004
A photoluminescence (PL) study of GaN grown on Si(100) substrate using porous silicon (PS) as an ... more A photoluminescence (PL) study of GaN grown on Si(100) substrate using porous silicon (PS) as an intermediate layer is reported. The samples were characterized using PL for the temperature range 5 -300 K under various excitation powers from 5 to 50 mW. For growth temperatures below 800 °C, the room temperature PL shows a broad peak located around cubic GaN emission. This is in clear contradiction with previous scanning electron microscopy and X-ray measurements. At low PL temperature, the observed lines located at 3.306 and 3.364 eV have a narrow full width at half maximum of about 6 and 10 meV, respectively. When the excitation power was varied, no peak shift was observed. These peaks were assigned as deeply localized excitons related to stacking faults near the PS/GaN interface. Quantum confinement (type I or II) due to the presence of nanometric cubic inclusions is another possible explanation for the low-temperature PL.
![Research paper thumbnail of Crystal Structure and Theoretical Symmetry Analysis of the Phase Transition Sequence in [(C2H5)4N]2PtCl6](https://attachments.academia-assets.com/41956088/thumbnails/1.jpg)
](physica status solidi (a), 1986
The crystal structure of the complex [(C2H,),N],PtCI, is determined by X-ray methods. The compoun... more The crystal structure of the complex [(C2H,),N],PtCI, is determined by X-ray methods. The compound crystallizes in the space group C2/c with a = 1.3888(3), 6 = 1.4006(5), c = 1.3252(4) nm, and / 3 = 90.53 (2)". The structure corresponds to a distorted K,PtCI,. The average Pt-CI bond length corrected for libration is 0.2326(4) nm. One of the two non equivalent cations is disordered. The structure has been solved by Patterson and Fourier syntheses and refined by least-squares methods to a final RF = 0.076 (weighted R, f = 0.053). The symmetry relationships between the Fm3m parent structure and the monoclinic one, are clarified. An intermediary phase transition is suggested to explain the symmetry change from C2/c to Fm3m high temperature space group. La X.
Phase Transitions, 1991
A phenomenological model is proposed for the nematic-smectic A–smectic C transition. Two order pa... more A phenomenological model is proposed for the nematic-smectic A–smectic C transition. Two order parameters which are biquadratically coupled are involved. The first one is primary and characterizes the appearance of layers in the smectic phases. The second order parameter is triggered by the first one and can be identified with the tilt angle.Analytic expressions are obtained for lines and points
Phase Transitions, 1991
ABSTRACT The tetraethylammonium hexachlorostannate [(C2H5)4N]2SnCl6 undergoes three phase transit... more ABSTRACT The tetraethylammonium hexachlorostannate [(C2H5)4N]2SnCl6 undergoes three phase transitions in the temperature range 200–400 K. The high-symmetry phase is described by the space group Fm3m. To carry out the symmetry relationships between Fm3m and the other observed space groups we introduce two primary order parameters, which transform according to the irreducible representations A2g, Eg of Fm3m at the X high symmetry point. These two order parameters are coupled to explain the symmetry change from Fm3m to a non maximal subgroup, in this case the induced representation is the direct sum A2g ⌖ Eg.
Phase Transitions, 1991
ABSTRACT
Microelectronics Journal, 2001
We report preliminary results on the growth of GaN on (100) Si substrate using porous silicon (PS... more We report preliminary results on the growth of GaN on (100) Si substrate using porous silicon (PS) as an intermediate buffer layer. The growth was in situ monitored by laser beam re¯ectivity. Analysis of the evolution of the re¯ectivity signal indicates a change from relativelȳ at surface to rough one as the growth temperature (T g ) is increased. At a temperature of about 10508C, the growth rate is very low and the re¯ected signal intensity is constant. When the growth temperature is varied, no drastic change of the porosity of the intermediate layer was detected. Scanning electron microscope (SEM) observations of the GaN/SP/Si structure revealed a good surface coverage at 5008C. When T g increases, the structure morphology changes to columnar like structure at 6008C, and well-developed little crystallites with no preferential orientation appear at 8008C. These observations agree well with the X-ray diffraction (XRD) analysis. A preferential hexagonal growth is obtained at low growth temperature, while cubic phase begin to appear at elevated temperatures. q
Materials Science and Engineering: B, 2006
ABSTRACT In this paper, we report the electric investigation of thin nitride gallium films by the... more ABSTRACT In this paper, we report the electric investigation of thin nitride gallium films by the capacitance voltage technique and the thermal step method (TSM). The C–V analysis at 1MHz of Au/GaN diode reveals MOS behaviour and shows strong capacitance hysteresis.This may be due to the presence of trapped charge in this structure. The space charge dynamics is studied by thermal step method at different applied voltages. The TS currents are reverted from negative ones to positive ones above inversion threshold of +0.2V. This change corresponds to charge modulation from accumulation to the inversion one, in good agreement with the C–V characteristics. The stored charge in this sample is related to the nature of gallium nitride and to the manufacturing processes. The results confirm the possibility to apply the TSM for the measurement of the space charge in the semiconductor materials.
Journal of Raman Spectroscopy, 1985
ABSTRACT
Journal of Physics C: Solid State Physics, 1983
Acta Crystallographica Section A Foundations of Crystallography, 1984
physica status solidi (b), 1984
ABSTRACT
Canadian Journal of Chemistry, 1984
Journal of Physics C Solid State Physics
The Raman spectra of the isomorphous compounds (CH&NMnCls, (CDs)dNMnC13 and (CH3)4NCdC13 in the r... more The Raman spectra of the isomorphous compounds (CH&NMnCls, (CDs)dNMnC13 and (CH3)4NCdC13 in the regions of the lattice vibrations and of the internal modes of the tetramethylammonium skeleton are reinvestigated at temperatures ranging from 300 to 25 K. On the basis of the hypothesis that group-to-subgroup relations exist between the high-and low-temperature phases of these compounds, a group theoretical analysis of possiblephase transitions has been made. Thecompatibility between the observed spectra and those predicted by group theory leads to the conclusion that for the cadmium compound the phase sequence could be
Journal of Physics C: Solid State Physics, 1982
The Raman spectra of the isomorphous compounds (CH&NMnCls, (CDs)dNMnC13 and (CH3)4NCdC13 in the r... more The Raman spectra of the isomorphous compounds (CH&NMnCls, (CDs)dNMnC13 and (CH3)4NCdC13 in the regions of the lattice vibrations and of the internal modes of the tetramethylammonium skeleton are reinvestigated at temperatures ranging from 300 to 25 K. On the basis of the hypothesis that group-to-subgroup relations exist between the high-and low-temperature phases of these compounds, a group theoretical analysis of possiblephase transitions has been made. Thecompatibility between the observed spectra and those predicted by group theory leads to the conclusion that for the cadmium compound the phase sequence could be
Physica Status Solidi (a), 1979
Physica Status Solidi (a), 1989
Physica Status Solidi (a), 1980
physica status solidi (b), 2003
In this paper we report electron beam induced current (EBIC) measurements on Schottky diodes on u... more In this paper we report electron beam induced current (EBIC) measurements on Schottky diodes on undoped GaN samples grown by the metal organic vapor phase epitaxy method on porous silicon substrates. A 2D simulation model was applied to perform the theoretical EBIC profiles and to compare with the experimental one. A minority carrier diffusion length (L) for holes of 0.72
physica status solidi (b), 1987
ABSTRACT
physica status solidi (a), 2004
A photoluminescence (PL) study of GaN grown on Si(100) substrate using porous silicon (PS) as an ... more A photoluminescence (PL) study of GaN grown on Si(100) substrate using porous silicon (PS) as an intermediate layer is reported. The samples were characterized using PL for the temperature range 5 -300 K under various excitation powers from 5 to 50 mW. For growth temperatures below 800 °C, the room temperature PL shows a broad peak located around cubic GaN emission. This is in clear contradiction with previous scanning electron microscopy and X-ray measurements. At low PL temperature, the observed lines located at 3.306 and 3.364 eV have a narrow full width at half maximum of about 6 and 10 meV, respectively. When the excitation power was varied, no peak shift was observed. These peaks were assigned as deeply localized excitons related to stacking faults near the PS/GaN interface. Quantum confinement (type I or II) due to the presence of nanometric cubic inclusions is another possible explanation for the low-temperature PL.
physica status solidi (a), 1986
The crystal structure of the complex [(C2H,),N],PtCI, is determined by X-ray methods. The compoun... more The crystal structure of the complex [(C2H,),N],PtCI, is determined by X-ray methods. The compound crystallizes in the space group C2/c with a = 1.3888(3), 6 = 1.4006(5), c = 1.3252(4) nm, and / 3 = 90.53 (2)". The structure corresponds to a distorted K,PtCI,. The average Pt-CI bond length corrected for libration is 0.2326(4) nm. One of the two non equivalent cations is disordered. The structure has been solved by Patterson and Fourier syntheses and refined by least-squares methods to a final RF = 0.076 (weighted R, f = 0.053). The symmetry relationships between the Fm3m parent structure and the monoclinic one, are clarified. An intermediary phase transition is suggested to explain the symmetry change from C2/c to Fm3m high temperature space group. La X.
Phase Transitions, 1991
A phenomenological model is proposed for the nematic-smectic A–smectic C transition. Two order pa... more A phenomenological model is proposed for the nematic-smectic A–smectic C transition. Two order parameters which are biquadratically coupled are involved. The first one is primary and characterizes the appearance of layers in the smectic phases. The second order parameter is triggered by the first one and can be identified with the tilt angle.Analytic expressions are obtained for lines and points
Phase Transitions, 1991
ABSTRACT The tetraethylammonium hexachlorostannate [(C2H5)4N]2SnCl6 undergoes three phase transit... more ABSTRACT The tetraethylammonium hexachlorostannate [(C2H5)4N]2SnCl6 undergoes three phase transitions in the temperature range 200–400 K. The high-symmetry phase is described by the space group Fm3m. To carry out the symmetry relationships between Fm3m and the other observed space groups we introduce two primary order parameters, which transform according to the irreducible representations A2g, Eg of Fm3m at the X high symmetry point. These two order parameters are coupled to explain the symmetry change from Fm3m to a non maximal subgroup, in this case the induced representation is the direct sum A2g ⌖ Eg.
Phase Transitions, 1991
ABSTRACT
Microelectronics Journal, 2001
We report preliminary results on the growth of GaN on (100) Si substrate using porous silicon (PS... more We report preliminary results on the growth of GaN on (100) Si substrate using porous silicon (PS) as an intermediate buffer layer. The growth was in situ monitored by laser beam re¯ectivity. Analysis of the evolution of the re¯ectivity signal indicates a change from relativelȳ at surface to rough one as the growth temperature (T g ) is increased. At a temperature of about 10508C, the growth rate is very low and the re¯ected signal intensity is constant. When the growth temperature is varied, no drastic change of the porosity of the intermediate layer was detected. Scanning electron microscope (SEM) observations of the GaN/SP/Si structure revealed a good surface coverage at 5008C. When T g increases, the structure morphology changes to columnar like structure at 6008C, and well-developed little crystallites with no preferential orientation appear at 8008C. These observations agree well with the X-ray diffraction (XRD) analysis. A preferential hexagonal growth is obtained at low growth temperature, while cubic phase begin to appear at elevated temperatures. q
Materials Science and Engineering: B, 2006
ABSTRACT In this paper, we report the electric investigation of thin nitride gallium films by the... more ABSTRACT In this paper, we report the electric investigation of thin nitride gallium films by the capacitance voltage technique and the thermal step method (TSM). The C–V analysis at 1MHz of Au/GaN diode reveals MOS behaviour and shows strong capacitance hysteresis.This may be due to the presence of trapped charge in this structure. The space charge dynamics is studied by thermal step method at different applied voltages. The TS currents are reverted from negative ones to positive ones above inversion threshold of +0.2V. This change corresponds to charge modulation from accumulation to the inversion one, in good agreement with the C–V characteristics. The stored charge in this sample is related to the nature of gallium nitride and to the manufacturing processes. The results confirm the possibility to apply the TSM for the measurement of the space charge in the semiconductor materials.
Journal of Raman Spectroscopy, 1985
ABSTRACT