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Title:
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Microwave Plasma Assisted VHF-PECVD of Micro-Crystalline Silicon
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Author(s):
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Soppe, W.J.; Bailat, J.; Droz, C.; Graf, U.; Kroll, U.; Meier, J.; Shah, A.
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Published by:
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Publication date:
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ECN
Solar Energy
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1-4-2002
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ECN report number:
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Document type:
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ECN-RX--02-012
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Conference Paper
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Number of pages:
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Full text:
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6
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Download PDF
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Presented at: 2002 MRS Spring Meeting, San Francisco, USA, 1-5 april 2002.
Abstract:
Growth of intrinsic micro-crystalline silicon layers by means of VHF-PECVD,assisted by remote microwave (MW) plasma has been investigated. The
aim of the microwave plasma is to enhance the deposition rate by introducing
additional excited hydrogen and Ar atoms in the VHF deposition zone.
For this purpose a remote microwave plasma source was constructed in
which a H2/Ar plasma is generated in a 20 mm diameter quartz tube. A
gas-shower has been constructed for homogeneous distribution of the
flow of excited gas species from the microwave source into the deposition
zone of the VHF-PECVD reactor where the dissociation of silane takes
place. At high microwave power (> 500 W) and undiluted hydrogen in the
MW source, an increase of the deposition rate of silicon by 20 % with
respect to pure VHF deposition was observed. The silicon
layers grown with MW assistance had a high oxygen content as a result
of a strong reduction of the quartz tube by the hydrogen plasma. In
a second series of experiments Ar dilution and reduced MW power were
used to eliminate the effect of etching of the tube by the microwave
hydrogen plasma. In this series of experiments an increase of the growth
rate of micro-crystalline silicon by about 15 % due to assistance of
the microwave plasma was found. Optical emission spectroscopy indicates
that ? in these experiments ? the main mechanism for the increased dissociation
of silane is through molecular quenching reaction of Ar * metastables.
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