This title appears in the Scientific Report :
2001
Hydrogen diffusion through deformed Si-Si bonds at grain boundaries in hot-wire CVD polycrystalline silicon films
Hydrogen diffusion through deformed Si-Si bonds at grain boundaries in hot-wire CVD polycrystalline silicon films
In this paper the site and bonding configurations of hydrogen have been probed to understand its thermal stability as well as defect passivation process. Secondary ion mass spectrometry (SIMS) depth profile of implanted deuterium showed that hydrogen migration in our device quality hot -wire chemica...
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Personal Name(s): | Rath, J. K. |
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Schropp, R. E. I. / Beyer, W. | |
Contributing Institute: |
Institut für Photovoltaik; IPV |
Published in: | Solid state phenomena, 80 - 81 (2001) S. 109 - 114 |
Imprint: |
Uetikon
Trans Tech Publ.
2001
|
Physical Description: |
109 - 114 |
Document Type: |
Journal Article |
Research Program: |
Grundlagen und Technologie von Dünnschichtsolarzellen |
Series Title: |
Solid State Phenomena
80 - 81 |
Subject (ZB): | |
Publikationsportal JuSER |
In this paper the site and bonding configurations of hydrogen have been probed to understand its thermal stability as well as defect passivation process. Secondary ion mass spectrometry (SIMS) depth profile of implanted deuterium showed that hydrogen migration in our device quality hot -wire chemical vapour deposition (HWCVD) poly-Si is diffusion limited. These films are characterised by Si-H vibration at 2000 cm(-1), not at 2100 cm(-1) as typically observed in poly-Si films. Though the coefficient (D similar to 10(-14) cm(2)s(-1)) of hydrogen diffusion in these films is similar to hydrogen implanted in c-Si, the diffusion prefactor, (D(o)similar to 10 cm(2)s(-1)), and activation energy (E(D)similar to2.1eV) are higher than those for c-Si implanted with comparable hydrogen content, but similar to those for amorphous silicon with comparable hydrogen content (either implanted or as grown). The hydrogen migration is anisotropic; it is predominantly at the grain boundary and negligible inside the c-Si grains. We attribute this behaviour to hydrogen diffusion through deformed. Si-Si bonds (at compact sites) inside thin grain boundary (we propose [110] tilt boundary) region. The diffusion coefficient is time independent, inferring that there are negligible voids in the network. The diffusion parameters follow Meyer-Neldel rule (which we attribute to statistical shift of chemical potential) that explains simultaneous high activation energy and diffusion prefactor. Diffusion characteristics is explained by a model of continuous hydrogen density of states distribution with a variation of trap depths depending on hydrogen concentration. |