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Metastable Phenomena in the Thermally Activated Conductivity of Hydrogenated Amorphous Germanium (a-Ge:H)

Published online by Cambridge University Press:  01 January 1993

T. DrÜsedau ,
D. Pang ,
E. Sauvain ,
P. Wickboldt ,
E.Z. Liu ,
J.H. Chen  and
W. Paul
T. DrÜsedau
Affiliation:
Harvard University, Division of Applied Sciences, Cambridge, MA 02138 Feodor Lynen-Fellow of the Alexander von Humboldt - Foundation, Inst. Exper. Physik, Tech. Univ. “Otto von Guericke” , O-3010 Magdeburg , Germany
D. Pang
Affiliation:
Harvard University, Division of Applied Sciences, Cambridge, MA 02138
E. Sauvain
Affiliation:
Division of Engineering, Brown University, Providence, RI 02912
P. Wickboldt
Affiliation:
Harvard University, Division of Applied Sciences, Cambridge, MA 02138
E.Z. Liu
Affiliation:
Harvard University, Division of Applied Sciences, Cambridge, MA 02138
J.H. Chen
Affiliation:
Boston College Dept. of Physics, Chestnut Hill, MA 02167
W. Paul
Affiliation:
Harvard University, Division of Applied Sciences, Cambridge, MA 02138
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Abstract

The activated conductivity of a-Ge:H between room temperature and 460K was investigated using heating and cooling rates in the range between .001 and 0.1 K/s. A splitting of the cooling curves obtained at different rates, which defines the so called equilibrium temperature TE, is observed mainly between 420 and 430K. Taking into consideration that TE depends on the maximum cooling rate, the present results are in good agreement with those reported by Eberhardt et al. The higher cooling rate always leads to the lower conductivity at any temperature below TE. These effects can be rationalized in terms of a reversible shift of the Fermi level towards midgap at higher temperature. Though reversible changes of the mobility cannot be excluded, they cannot account for our set of experimental data. Rather, changes in the density of electronic states within the mobility gap can explain the effects observed.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 297: Symposium A – Amorphous Silicon Technology - 1993 , 1993 , 729
Copyright
Copyright © Materials Research Society 1993

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References

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