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Defect Relaxation Dynamics in Amorphous Silicon

Published online by Cambridge University Press:  01 January 1993

J. David Cohen ,
Thomas M. Leen ,
Fan Zhong  and
R.J. Rasmussen
J. David Cohen
Affiliation:
Department of Physics and Materials Science Institute, University of Oregon, Eugene, OR 97403
Thomas M. Leen
Affiliation:
Department of Physics and Materials Science Institute, University of Oregon, Eugene, OR 97403
Fan Zhong
Affiliation:
Department of Physics and Materials Science Institute, University of Oregon, Eugene, OR 97403
R.J. Rasmussen
Affiliation:
Department of Physics and Materials Science Institute, University of Oregon, Eugene, OR 97403
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Abstract

Using transient capacitance and transient spin techniques, we have the determined the manner in which the mobility gap energy of the D defect is altered following a change in its charge state. This relaxation process gives rise to a power law rather an exponential thermal release of defect electrons with time and also causes the charge emission and spin transients to obey a scaling law. We also deduce that the D°/D+ transition rate depends on the tenure of the proceeding D-/D° transition. This last aspect of the D defect emission behavior implies that it must be treated as a non-Markovian process. Such relaxation dynamics have profound consequences for the steady state distribution of D defect energies. Using the relaxation parameters determined by the transient measurements we have been able to solve a set of coupled differential equations under steady-state conditions to provide the energy distributions of both the D° and DD+ defect sub-bands. The results of these calculations agree remarkably well with the experimental distributions determined by modulated photocurrent and steady-state capacitance measurements. This implies that the statistical variations in the occupation history of the defect may be the dominant factor determining both distributions.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 297: Symposium A – Amorphous Silicon Technology - 1993 , 1993 , 183
Copyright
Copyright © Materials Research Society 1993

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References

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