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a-Si:H and a-SiGe:H Alloys Fabricated Close to Powder Regime of RF PECVD

Published online by Cambridge University Press:  15 February 2011

A. R. Middya ,
Suktihazra ,
Swati Ray ,
C. Longeaud  and
J. P. Kleider
A. R. Middya
Affiliation:
Laboratoire de Physique des Interfaces et Couches Minces (CNRS, UPR 258), Ecole Polytechnique, F-91128, Palaiseau Cedex, FRANCE
Suktihazra
Affiliation:
Energy Research Unit, Indian Association for the Cultivation of Science, Jadavpur, Calcutta - 700 032, INDIA
Swati Ray
Affiliation:
Energy Research Unit, Indian Association for the Cultivation of Science, Jadavpur, Calcutta - 700 032, INDIA
C. Longeaud
Affiliation:
Laboratoire de Génie Electrique de Paris (CNRS, URA 0127), Ecole Supérieure d'Electricité, Universités Paris VI et Paris XI, Plateau de Moulon, 91192 Gif-Sur-Yvette Cedex, FRANCE
J. P. Kleider
Affiliation:
Laboratoire de Génie Electrique de Paris (CNRS, URA 0127), Ecole Supérieure d'Electricité, Universités Paris VI et Paris XI, Plateau de Moulon, 91192 Gif-Sur-Yvette Cedex, FRANCE
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Abstract

We have been observing that a-Si:H and a-SiGe:H films deposited under high chamber pressure or close to powder regime (500 to 2000 mT for a-Si:H and 200 to 1000 mT for a-SiGe:H) show many new features : the mobility lifetime product is 10 to 100 times higher and the density of states above Fermi level of a-Si:H and a-SiGe:H ([Ge] < 0.20) is lower than that of standard samples. This enhancement in photoconductivity can neither be attributed to autodoping nor to creation of sensitization centers in the samples. Hydrogen bonding of these films, is mostly monohydride and the density of microstructural (polyhydrides and microvoids) defects is low. Evidence for the presence of nanocrystals is noted. Though the films seems amorphous by all conventional techniques, they crystallize easily under low laser intensity. Kinetics of light induced degradation is very fast (less than 20 hrs), for a-Si:H and the value of photoconductivity in the light soaked state is comparable to that of the standard samples in the annealed state. The process gas utilization efficiency in this regime is also higher than in the low power and pressure regime.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 467: Symposium A – Amorphous and Microcrystalline Silicon Technology - 1997 , 1997 , 615
Copyright
Copyright © Materials Research Society 1997

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References

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