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Evolution of Charged Gap Statesin a- Si:H Under Light Exposure

Published online by Cambridge University Press:  01 February 2011

M. Zeman
Affiliation:
Delft University of Technology – DIMES, P.O. Box 5053, 2600 GB Delft, The Netherlands
V. Nádaždy
Affiliation:
Delft University of Technology – DIMES, P.O. Box 5053, 2600 GB Delft, The Netherlands
R.A.C.M.M. van Swaaij
Affiliation:
Delft University of Technology – DIMES, P.O. Box 5053, 2600 GB Delft, The Netherlands
R. Durný
Affiliation:
Slovak University of Technology, Ilkovičova 3, 812 19 BratislavaSlovakia
J.W. Metselaar
Affiliation:
Delft University of Technology – DIMES, P.O. Box 5053, 2600 GB Delft, The Netherlands
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Abstract

The charge deep-level transient spectroscopy (Q-DLTS) experiments on undoped hydrogenated amorphous silicon (a-Si:H) demonstrate that during light soaking the states in the upper part of the gap disappear, while additional states around and below midgap are created. Since no direct correlation is observed in light-induced changes of the three groups of states that we identify from the Q-DLTS signal, we believe that we deal with three different types of defects. Positively charged states above midgap are related to a complex formed by a hydrogen molecule and a dangling bond. Negatively charged states below midgap are attributed to floating bonds. Various trends in the evolution of dark conductivity due to light soaking indicate that the kinetics of light-induced changes of the three gap-state components depend on their initial energy distributions and on the spectrum and intensity of light during exposure.

Type
Research Article
Copyright
Copyright © Materials Research Society 2003

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