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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.

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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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