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Modification of a-Si(:H) by Thermally Generated Atomic Hydrogen: A Real Time Spectroscopic Ellipsometry Study of Si Bond Breaking

Published online by Cambridge University Press:  21 February 2011

Ilsin An
Affiliation:
Materials Research Laboratory, The Pennsylvania State University, University Park, PA 16802
Youming Li
Affiliation:
Materials Research Laboratory, The Pennsylvania State University, University Park, PA 16802
C.R. Wronski
Affiliation:
Materials Research Laboratory, The Pennsylvania State University, University Park, PA 16802
R.W. Collins
Affiliation:
Materials Research Laboratory, The Pennsylvania State University, University Park, PA 16802
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Abstract

We have applied real time spectroscopie ellipsometry (2.5≤hv≤4.5 eV) to investigate in situ hydrogenation of thin film a-Si:H prepared by plasma-enhanced CVD. When a-Si:H is exposed to atomic H generated by a tungsten filament heated in H2, as many as ∼5×1021 Si-Si bonds/cm3 can be converted to Si-H bonds in the top ∼200 Å of the film. We have determined the spectroscopie characteristics of Si-H bonds from optical to near-uv photon energies through an analysis of the changes in the dielectric function of the near-surface of the film upon hydrogenation. The conversion of Si-Si bonds to Si-H bonds is identified as reaction-limited to a depth of ∼500 Å. We find that a surface oxide a few monolayers in thickness acts as an effective diffusion barrier to H-incorporation.

Type
Research Article
Copyright
Copyright © Materials Research Society 1992

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References

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