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Title: Spectroscopic analysis of H{sub 2}/CH{sub 4} microwave plasma and fast growth rate of diamond single crystal

One of the best ways to increase the diamond growth rate is to couple high microwave power to the plasma. Indeed, increasing the power density leads to increase gas temperature the atomic hydrogen density in the plasma bulk, and to produce more hydrogen and methyl at the diamond surface. Experimental and numerical approaches were used to study the microwave plasma under high power densities conditions. Gas temperature was measured by optical emission spectroscopy and H-atom density using actinometry. CH{sub 3}-radical density was obtained using a 1D model that describes temperatures and plasma composition from the substrate to the top of the reactor. The results show that gas temperature in the plasma bulk, atomic hydrogen, and methyl densities at the diamond surface highly increase with the power density. As a consequence, measurements have shown that diamond growth rate also increases. At very high power density, we measured a growth rate of 40 μm/h with an H-atom density of 5 × 10{sup 17} cm{sup −3} which corresponds to a H{sub 2} dissociation rate higher than 50%. Finally, we have shown that the growth rate can be framed between a lower and an upper limit as a function depending only on the maximum ofmore » H-atom density measured or calculated in the plasma bulk. The results also demonstrated that increasing fresh CH{sub 4} by an appropriate injection into the boundary layer is a potential way to increase the diamond growth rates.« less
Authors:
; ; ;  [1]
  1. Laboratoire des Sciences des Procédés et des Matériaux (LSPM), UPR3407 CNRS, Université Paris 13, 99 Avenue Jean Baptiste Clément, 93430 Villetaneuse (France)
Publication Date:
OSTI Identifier:
22303980
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 23; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; BOUNDARY LAYERS; CRYSTAL GROWTH; CRYSTALS; DIAMONDS; DISSOCIATION; EMISSION SPECTROSCOPY; HYDROGEN; INJECTION; METHANE; MICROWAVE RADIATION; MOLECULAR IONS; MONOCRYSTALS; PLASMA; POWER DENSITY; SUBSTRATES; SURFACES