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S. Lebib

Bio: S. Lebib is an academic researcher from École Polytechnique. The author has contributed to research in topics: Silicon & Thin film. The author has an hindex of 7, co-authored 10 publications receiving 214 citations.

Papers
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Journal ArticleDOI
TL;DR: In this paper, the effects of substrate temperature, radiofrequency power, and total pressure on the crystal size and hydrogen bonding in nanocrystalline silicon thin films codeposited on the grounded and rf electrodes of an asymmetric radio frequency glow discharge reactor were studied.
Abstract: We present a detailed study of the effects of the substrate temperature, radio-frequency (rf) power, and total pressure on the crystal size and hydrogen bonding in nanocrystalline silicon thin films codeposited on the grounded and rf electrodes of an asymmetric radio frequency glow discharge reactor. Raman spectroscopy, x-ray diffraction, and spectroscopic ellipsometry measurements show that by varying the deposition parameters we can obtain crystal sizes in the range of 3–10nm and crystalline fractions in the range of 20% up to 97%. The obtaining of small crystallite sizes (4–5nm) in films submitted to high-energy (100–300eV) ion bombardment is highlighted by infrared-absorption and hydrogen evolution measurements, which display characteristic features of hydrogen bonded at the surface of the crystallites. Therefore, hydrogen bonding is a unique way to demonstrate the presence of small crystallites in films at the transition between amorphous and nanocrystalline, films which look amorphous when character...

53 citations

Journal ArticleDOI
TL;DR: In this article, a study on the deposition of polymorphous silicon at an excitation frequency of 27.12 MHz in a large-area plasma enhanced chemical vapor deposition (PECVD) reactor is presented.
Abstract: This work presents for the first time a study on the deposition of polymorphous silicon at an excitation frequency of 27.12 MHz in a large-area plasma enhanced chemical vapor deposition (PECVD) reactor. Moreover, the films produced at 13.56 MHz were also investigated to compare their performance with that of the films produced at 27.12 MHz. The SiH4/H2 plasma was characterized by impedance probe measurements, aiming to identify the plasma conditions that lead to produce polymorphous films, under quasi-isothermal conditions. The films were characterized by spectroscopic ellipsometry, infrared absorption, Raman spectroscopy, and hydrogen exodiffusion experiments. These techniques enable a detailed structural characterization of the polymorphous films and a study of the differences between the films deposited at 27.12 MHz and 13.56 MHz. Conductivity measurements were also performed to determine the transport properties of the films. The results show that by using a 27.12 MHz frequency, the growth rate increased by 70% and a more stable, relaxed and denser structure was obtained.

37 citations

Journal ArticleDOI
TL;DR: In this paper, a detailed study of the structure and hydrogen bonding in silicon thin films ranging from amorphous to microcrystalline is presented, and the results for hydrogenated polymorphous silicon films obtained under plasma conditions close to powder formation where silicon clusters and nanocrystals contribute to growth.
Abstract: We present a detailed study of the structure and hydrogen bonding in silicon thin films ranging from amorphous to microcrystalline. We emphasize the results for hydrogenated polymorphous silicon films obtained under plasma conditions close to powder formation where silicon clusters and nanocrystals contribute to growth. Fourier Transform Infra-Red (FTIR) spectroscopy, Raman spectroscopy, X-Ray-Diffraction (XRD), and hydrogen evolution measurements are performed to characterize the hydrogen bonding and the structure of the films in their as-deposited state and after isochronal annealing at increasing temperature in the range of 300 to 600 °C. While Raman spectroscopy and XRD give an average information on the structure of the films, without clear evidence of the presence of crystallites in the polymorphous films, infrared spectroscopy and hydrogen evolution measurements which probe the local hydrogen related structure are shown to be perfectly adapted to characterize polymorphous silicon films. In particular, IR spectroscopy measurements, reveal the presence of a stretching band at 2030 cm −1 , associated with a peak at 873 cm −1 in the bending region and a downward shift in the Si-H wagging mode from 640 cm −1 to 622 cm −1 . We attribute the 2030 cm −1 mode to the presence of hydrogen bonded at the surface of the plasma produced silicon clusters and nanocrystals. This assignment is supported by hydrogen evolution measurements in which a sharp low-temperature hydrogen evolution peak appears at around 420 °C followed by up to five peaks at higher temperatures. This particular hydrogen bonding in polymorphous silicon films is also supported by isochronal annealing studies which show that the bands at 2030 cm −1 and 873 cm −1 vanish at annealing temperatures corresponding to the low temperature hydrogen evolution peak. Based on these results and their correlation with the hydrogen-related material structure, we propose a picture for the structure of polymorphous silicon films that accounts for the observed features.

35 citations

Journal ArticleDOI
TL;DR: The optical, defect-related, and transport properties of both types of carriers have been studied using a set of complementary techniques before light soaking, after light soaking and after subsequent annealing as discussed by the authors.
Abstract: Hydrogenated polymorphous silicon–germanium samples with Ge content x up to 0.35 have been deposited in a plasma-enhanced chemical vapor deposition system from silane and germane precursors highly diluted in hydrogen and in a high pressure range. The optical, defect-related, and transport properties of both types of carriers have been studied using a set of complementary techniques before light soaking, after light soaking, and after subsequent annealing. Before light soaking, we observe a small deterioration of the electron transport properties with increasing Ge content. This is related to the widening of the conduction band tail and to the increase of a deep defect band with emission energies at about 0.4 eV below the conduction transport path, which is attributed to Ge dangling bonds. The hole transport properties are much less sensitive to the incorporation of Ge, which we attribute to the unchanged Urbach tail parameter. Light soaking results in a deterioration of the transport properties due to an ...

28 citations

Journal ArticleDOI
TL;DR: In this paper, the authors compare the hydrogen incorporation and the optoelectronic properties of hydrogenated polymorphous silicon (pm-Si:H) films deposited by the decomposition of either silane-hydrogen or silanehelium mixtures.
Abstract: Here we compare the hydrogen incorporation and the optoelectronic properties of hydrogenated polymorphous silicon (pm-Si:H) films deposited by the decomposition of either silane–hydrogen or silane–helium mixtures. The use of He dilution leads to higher deposition rate and films with a lower hydrogen content with respect to hydrogen dilution. On the contrary, hydrogen dilution leads to films with high hydrogen content that show a characteristic infrared stretching band at 2040 cm−1. We propose that this absorption band is due to hydrogen bonded at the surface of crystallites and clusters in a platelet-like configuration. This peculiar hydrogen bonding is related to low temperature hydrogen diffusion, which gives rise to a sharp hydrogen effusion peak at around 420 °C. Interestingly enough, the higher deposition rate in the films from the He-dilution series does not result in degradation of the film’s electronic and transport properties, which are strongly improved with respect to those of standard amorphou...

27 citations


Cited by
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Journal ArticleDOI
TL;DR: An overview of dynamic self-organization phenomena in complex ionized gas systems, associated physical phenomena, and industrial applications is presented in this paper, where the most recent experimental, theoretical, and modeling efforts to understand the growth mechanisms and dynamics of nano- and micron-sized particles, as well as the unique properties of the plasma-particle systems (colloidal, or complex plasmas) and the associated physical effects are reviewed and the major technological applications of micro- and nanoparticles are discussed.

322 citations

Journal ArticleDOI
TL;DR: In this paper, the role of processing parameters on the electrical performance of GIZO (Ga 2 O 3 :In 2O 3 :ZnO) films and thin-film transistors (TFTs) was analyzed.
Abstract: This work analyzes the role of processing parameters on the electrical performance of GIZO (Ga 2 O 3 :In 2 O 3 :ZnO) films and thin-film transistors (TFTs). Parameters such as oxygen partial pressure, deposition pressure, target composition, thickness, and annealing temperature are studied. Generally, better devices are obtained when low oxygen partial pressure is used. This is related to the damage induced by oxygen ion bombardment and very high film's resistivity when higher oxygen partial pressures are used. Low deposition pressures and targets with richer indium compositions led to films with high carrier concentration, resulting in transistors with field-effect mobility as high as ∼ 80 cm 2 /Vs but poor channel conductivity modulation, becoming ineffective as switching devices. Nevertheless, it is demonstrated that reducing the GIZO thickness from 40 to 10 nm greatly enhances the switching behavior of those devices, due to the lower absolute number of free carriers and hence to their easier depletion. Annealing also proves to be crucial to control device performance, significantly modifying GIZO electrical resistivity and promoting local atomic rearrangement, being the optimal temperature determined by the as-produced films' properties. For the best-performing transistors, even with a low annealing temperature (150°C), remarkable properties such as μ FE = 73.9 cm 2 /Vs, on/off ratio as 7 × 10 7 , V T ≈ 0.2 V, and S = 0.29 V/dec are achieved.

255 citations

Patent
17 Jun 2005
TL;DR: In this paper, a method for the synthesis of single-crystal semiconductor nanoparticles, including photoluminescent silicon nanoparticles with diameters of no more than 10 nm, is described.
Abstract: Methods and apparatus for producing nanoparticles, including single-crystal semiconductor nanoparticles, are provided. The methods include the step of generating a constricted radiofrequency plasma in the presence of a precursor gas containing precursor molecules to form nanoparticles. Single-crystal semiconductor nanoparticles, including photoluminescent silicon nanoparticles, having diameters of no more than 10 nm may be fabricated in accordance with the methods.

191 citations

Journal ArticleDOI
TL;DR: In this article, the tetrahedron model was used to determine the hydrogen content, the crystalline fraction, and the void fraction of amorphous and polymorphous silicon films from UV-visible spectroscopic ellipsometry measurements.
Abstract: The dielectric functions of amorphous and polymorphous silicon films prepared under various plasma conditions have been deduced from UV-visible spectroscopic ellipsometry measurements. The measured spectra have been firstsimulated by the use of the Tauc-Lorentz dispersion model and then the compositions of the films have been obtained by the use of the tetrahedron model combined with the Bruggeman effective medium approximation. This approach allows us to determine the hydrogen content, the crystalline fraction, and the void fraction of the films. This is particularly important in the case of polymorphous films in which the low crystalline fraction (below 10%) can only be detected when an accurate description of the effects of hydrogen on the dielectric function through the tetrahedron model is considered. The hydrogen content and film porosity deduced from the analysis of the spectroscopic ellipsometry measurements are in excellent agreement with the hydrogen content and film density deduced from combined elastic recoil detection analysis and Rutherford backscattering spectroscopy measurements. Moreover, despite their high hydrogen content (∼15%-20%) with respect to hydrogenated amorphous silicon films deposited at the same temperature (8%), polymorphous silicon films have a high density, which is related to their very low void fraction.

181 citations

Journal ArticleDOI
TL;DR: In this article, some fundamental aspects of a complex system involving plasma particles and dust particles in a collective way are reviewed and possible applications are discussed, as well as possible applications of such systems.
Abstract: Dust particles in a plasma are charged negatively and are subject to various types of forces, including a drag force by plasma particles and a force due to the collective nature of a plasma. Dust particles are found in a sheath in laboratories balanced by the gravitational force and the electric force, while dust particles in space are ubiquitous, including planetary magnetospheres and interstellar space. Because of the novel nature of a complex system involving plasma particles and dust particles in a collective way, the dusty plasma is often called a complex plasma. The complex plasma is characterized by two distinctly different scales in time and in space. The plasma with electrons, ions and neutrals is characterized by the collective motion with a fast time scale and a short wavelength, while the dust particles move in a slow time scale and a long spatial scale. Some fundamental aspects of a complex plasma are reviewed and possible applications are discussed.

170 citations