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Caractérisation d'une décharge micro-onde pulsée dans le mélange CH4-H2 en vue de son optimisation pour la synthèse de films de diamant

Abstract : Owing to its very good physico-chemical properties, diamond is an excellent candidate for applications in optics and in electronics intended to work in hard conditions (high power, high frequençy and high temperature). These applications need high purity diamond to be synthetize. As a consequence, many research works showed that Microwave Plasma Assisted Chemical Vapour Deposition (MWPACVD) is the most suitable process for diamond films deposition. The original aspect of this work concerns the study of the influence of pulsed microwave dis charge parameters - especially the power pulse duration and repetition rate- on the plasma reactivity and the diamond layer properties. Sample characterization was carried out by means of Scanning Electron Microscopy and Raman Spectroscopy. These analyses allowed us to show that an optimum in diamond film quality is reached, without lowering the film growth rate, when both the microwave pulse duration and the afterglow are fixed at 1 ms. The plasma diagnostic was perfomed by using Time Resolved Optical Emission Spectroscopy (TROES), Laser Induced Fluorescence (LIF) and the "double pulse technique" that allows the ground state of species to be re-excited during the afterglow. The influence of the time parameters of the plasma on the gas phase composition was correlated to the modification in the diamond film properties. The time and space resolved study of the main reactive species shows that a gooq adjustment of the power pulse duration and repetition rate allows the concentration of these species to be controlled. Furthermore, we point out that the main processes which govern such pulsed plasma are thermal effects (heating and cooling of the neutral gas) and diffusion to the walls. These points make necessary the time and space resolved plasma characterization.
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http://docnum.univ-lorraine.fr/prive/SCD_T_2000_0126_POUCQUES.pdf
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https://hal.univ-lorraine.fr/tel-01746479
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Submitted on : Thursday, March 29, 2018 - 10:38:39 AM
Last modification on : Wednesday, March 24, 2021 - 10:22:02 AM

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Ludovic de Poucques. Caractérisation d'une décharge micro-onde pulsée dans le mélange CH4-H2 en vue de son optimisation pour la synthèse de films de diamant. Autre [cond-mat.other]. Université Henri Poincaré - Nancy 1, 2000. Français. ⟨NNT : 2000NAN10126⟩. ⟨tel-01746479⟩

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