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Journal ArticleDOI

Nanopowder of silicon nitride produced in radio frequency modulated glow discharges from SiH4 and NH3

TL;DR: In this paper, the authors reported the production of SiN nanopowder at room temperature and low pressure by RF glow discharge decomposition of SiH 4 and NH 3 gases, where the RF power was modulated at 0.5 Hz with a duty cycle of 20% in order to control the size of the expelled particles.
Abstract: Square-wave modulated radio frequency (RF) plasmas have been shown to be a suitable source of nanometric size powder with high purity and controllable nanostructure. This paper reports the production of SiN nanopowder at room temperature and low pressure by RF glow discharge decomposition of SiH 4 and NH 3 gases. The RF power was modulated at 0.5 Hz with a duty cycle of 20% in order to control the size of the expelled particles. A study of the particle formation process using in-situ monitoring of the RF dissipated power is presented. Transmission electron microscopy showed a narrow size distribution of spherical particles from 25 to 45 nm and their electron diffraction provided evidence of a short range order in Si or SiN units depending on the precursor gas mixture. Analysis by Fourier transform infrared spectroscopy revealed the presence of SiN, NH and SiH bonds and the elemental analysis of the powder determined its chemical composition.
Citations
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Journal ArticleDOI
TL;DR: In this paper, a review of the state of the art on materials produced by fluidized bed chemical vapor deposition (FBCVD) is presented, where the authors focus on the ways to ensure such contact and particularly on the formation of fluidized beds.
Abstract: Chemical vapor deposition (CVD) is an important technique for surface modification of powders through either grafting or deposition of films and coatings. The efficiency of this complex process primarily depends on appropriate contact between the reactive gas phase and the solid particles to be treated. Based on this requirement, the first part of this review focuses on the ways to ensure such contact and particularly on the formation of fluidized beds. Combination of constraints due to both fluidization and chemical vapor deposition leads to the definition of different types of reactors as an alternative to classical fluidized beds, such as spouted beds, circulating beds operating in turbulent and fast-transport regimes or vibro-fluidized beds. They operate under thermal but also plasma activation of the reactive gas and their design mainly depends on the type of powders to be treated. Modeling of both reactors and operating conditions is a valuable tool for understanding and optimizing these complex processes and materials. In the second part of the review, the state of the art on materials produced by fluidized bed chemical vapor deposition is presented. Beyond pioneering applications in the nuclear power industry, application domains, such as heterogeneous catalysis, microelectronics, photovoltaics and protection against wear, oxidation and heat are potentially concerned by processes involving chemical vapor deposition on powders. Moreover, simple and reduced cost FBCVD processes where the material to coat is immersed in the FB, allow the production of coatings for metals with different wear, oxidation and corrosion resistance. Finally, large-scale production of advanced nanomaterials is a promising area for the future extension and development of this technique.

202 citations

Journal ArticleDOI
TL;DR: In this paper, a silicon nitride nanowires were synthesized using silicon monoxide as raw materials and an alumina plate as substrate at 1500°C, where X-ray diffraction was used to characterize them.
Abstract: Silicon nitride nanowires were synthesized using silicon monoxide as raw materials and an alumina plate as substrate at 1500°C. The obtained nanowires were characterized by X-ray diffraction, Fouri...

14 citations


Cites background from "Nanopowder of silicon nitride produ..."

  • ...The peak at 1041 cm-1 is associated with a Si-OSi stretching mode [22] and reveals that the Si3N4 nanowires possess oxygen, and bonds with silicon....

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Journal ArticleDOI
TL;DR: In this article, the anti-reflection coating (ARC) layer was modified with pulsed-plasma (PP) PECVD to deal with potential-induced degradation (PID).
Abstract: The issue of potential-induced degradation (PID) has gained more concerns due to causing the catastrophic failures in photovoltaic (PV) modules. One of the approaches to diminish PID is to modify the anti-reflection coating (ARC) layer upon the front surface of crystalline silicon solar cells. Here, we focus on the modification of ARC films to realize PID-free step-by-step through three delicate experiments. Firstly, the ARC films deposited by direct plasma enhanced chemical vapor deposition (PECVD) and by indirect PECVD were investigated. The results showed that the efficiency degradation of solar cells by indirect PECVD method is up to −33.82%, which is out of the IEC 62804 standard and is significantly more severe than by the direct PECVD method (−0.82%). Next, the performance of PID-resist for the solar cell via indirect PECVD was improved significantly (PID reduced from −31.82% to −2.79%) by a pre-oxidation step, which not only meets the standard but also has higher throughput than direct PECVD. Lastly, we applied a novel PECVD technology, called the pulsed-plasma (PP) PECVD method, to deal with the PID issue. The results of the HF-etching rate test and FTIR measurement indicated the films deposited by PP PECVD have higher potential against PID in consideration of less oxygen content in this film. That demonstrated the film properties were changed by applied a new control of freedom, i.e., PP method. In addition, the 96 h PID result of the integrated PP method was only −2.07%, which was comparable to that of the integrated traditional CP method. In summary, we proposed three effective or potential approaches to eliminate the PID issue, and all approaches satisfied the IEC 62804 standard of less than 5% power loss in PV modules.

11 citations


Cites methods from "Nanopowder of silicon nitride produ..."

  • ...reported a high purity and cont ollabl nanostructure achieved by the PP method [19], and Byungwhan Kim et al....

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  • ...reported a high purity and controllable nanostructure achieved by the PP method [19], and Byungwhan Kim et al....

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Journal ArticleDOI
TL;DR: In this article, the kinetics of SiO vapor ammonolysis to produce nano-sized silicon nitride powder was studied with an 80mm-diameter vertical tubular flow reactor operated at temperatures ranging from 1300 °C to 1400 °C.

9 citations

Journal ArticleDOI
TL;DR: In this article, a sine-wave modulated rf plasma has been used to control particle generation and growth in a plasma-enhanced chemical vapor deposition of silicon dioxide thin films using TEOS/O2.
Abstract: Sine-wave modulated rf plasma has been used to control particle generation and growth in a plasma-enhanced chemical vapor deposition of silicon dioxide thin films using TEOS/O2. The density and the size of particles generated in the plasma are greatly reduced when the plasma is modulated with sine-wave modulation at low modulation frequency (<1000 Hz). In addition, particle contamination on the films is significantly reduced also for nanoparticles, and the film growth rates at the range of modulation frequencies where particle generation are greatly reduced do not decrease appreciably. Compared to its counterpart pulse-wave modulation plasma, the sine-wave modulation plasma has demonstrated a better performance in terms of reduction of particle generation and film contamination, and of film growth rate. Thus, the sine-wave modulation plasma has shown as a promising method to be applied in the production of thin film with a high deposition rate and a low particle contamination.

8 citations


Cites background from "Nanopowder of silicon nitride produ..."

  • ...However, since pulse-wave modulation is realized by switching the rf power on-off at a high repetition rate, the plasma operation may become unstable and it may lead to alter the process conditions (Viera et al., 1998)....

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References
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Book
28 Oct 1994
TL;DR: In this paper, the authors introduce the concept of particle and energy balance in discharges and introduce the theory of collision dynamics and wave-heated discharges, as well as chemical reactions and equilibrium.
Abstract: 1. Introduction. 2. Basic Plasma Equations and Equilibrium. 3. Atomic Collisions. 4. Plasma Dynamics. 5. Diffusion and Transport. 6. DC Sheaths. 7. Chemical Reactions and Equilibrium. 8. Molecular Collisions. 9. Chemical Kinetics and Surface Processes. 10. Particle and Energy Balance in Discharges. 11. Capacitive Discharges. 12. Inductive Discharges. 13. Wave-Heated Discharges. 14. DC Discharges. 15. Etching. 16. Deposition and Implantation. 17. Dusty Plasmas. 18. Kinetic Theory of Discharges. Appendix A: Collision Dynamics. Appendix B: The Collision Integral. Appendix C: Diffusion Solutions for Variable Mobility Model.

5,728 citations

Journal ArticleDOI
TL;DR: In this article, the particle growth is considered in an analytical model as a chain of negative ion molecular reactions, stimulated by vibrational excitation, and a limitation of first generation particle size is explained as well as the strong temperature effect on cluster growth.
Abstract: Kinetics of the many‐stage process of particle nucleation and growth in low‐pressure rf discharge in silane SiH4–Ar is considered. The particle growth is considered in an analytical model as a chain of negative‐ion molecular reactions, stimulated by vibrational excitation. In the framework of this model, a limitation of first generation particle size is explained as well as the strong temperature effect on cluster growth. A theory of critical phenomena of cluster trapping in discharge area has been elaborated to describe the neutral particle selection by size, and the particle concentration increases during a period exceeding the residence time in plasma. Finally, an analytical model of critical phenomena of particle coagulation and its influence on plasma parameters is developed to explain the latest experimental results on supersmall 2–10 nm cluster kinetics. All theoretical results are presented in comparison with corresponding new experimental data and with results of an especially made computer simulation.

195 citations

Journal ArticleDOI
TL;DR: In this paper, negative ions were only observed over a limited range of power modulation frequency which corresponds to particle-free plasma conditions, and the importance of negative ions regarding particulate formation was demonstrated and commented upon.
Abstract: Negative ions have been clearly identified in silane rf plasmas used for the deposition of amorphous silicon. Mass spectra were measured for monosilicon up to pentasilicon negative ion radical groups in power‐modulated plasmas by means of a mass spectrometer mounted just outside the glow region. Negative ions were only observed over a limited range of power modulation frequency which corresponds to particle‐free plasma conditions. The importance of negative ions regarding particulate formation is demonstrated and commented upon.

109 citations

Journal ArticleDOI
TL;DR: In this paper, experimental evidence for the deposition of nanoparticles, even in the case of a continuous discharge, has been presented, from a comparison of the growth kinetics and the optical properties of films obtained under continuous and modulated discharges.
Abstract: These last few years a great effort has been made to understand the mechanisms of powder formation in silane discharges. It is now well established that powders are negatively charged and thus confined in the plasma. Therefore, one does not expect powders to contribute to the deposition, unless the plasma is switched off. We present here experimental evidence for the deposition of nanoparticles, even in the case of a continuous discharge. Experimental conditions for nanoparticle formation while avoiding powder formation have been determined from light‐scattering and transmission electron microscopy measurements. Nanoparticle deposition has been studied by in situ ellipsometry in silane–argon discharges. From a comparison of the growth kinetics and the optical properties of films obtained under continuous and modulated discharges we conclude that nanoparticle deposition can take place even when the discharge is on. The implications of these discoveries on the properties of hydrogenated amorphous silicon ar...

98 citations

Journal ArticleDOI
TL;DR: In this article, the authors used a Brownian free molecule coagulation model to determine the time evolution of particle size and their number density in situ multi-angle polarization-sensitive laser light scattering.
Abstract: To determine self-consistently the time evolution of particle size and their number density in situ multi-angle polarization-sensitive laser light scattering was used. Cross-polarization intensities (incident and scattered light intensities with opposite polarization) measured at 135 degrees and ex situ transmission electronic microscopy analysis demonstrate the existence of nonspherical agglomerates during the early phase of agglomeration. Later in the particle time development both techniques reveal spherical particles again. The presence of strong cross-polarization intensities is accompanied by low-frequency instabilities detected on the scattered light intensities and plasma emission. It is found that the particle radius and particle number density during the agglomeration phase can be well described by the Brownian free molecule coagulation model. Application of this neutral particle coagulation model is justified by calculation of the particle charge whereby it is shown that particles of a few tens of nanometer can be considered as neutral under our experimental conditions. The measured particle dispersion can be well described by a Brownian free molecule coagulation model including a log-normal particle size distribution. (C) 1996 American Institute of Physics.

90 citations