Accession Number:

ADA209081

Title:

Experimental and Theoretical Study of Transient Behavior of Varistors

Descriptive Note:

Final rept. 11 Jan 1988-10 Jan 1989

Corporate Author:

NORTH CAROLINA UNIV AT CHAPEL HILL DEPT OF PHYSICS AND ASTRONOMY

Personal Author(s):

Report Date:

1989-04-25

Pagination or Media Count:

11.0

Abstract:

Transient currents below and above the breakdown voltage have been studied for metal oxide zinc oxide varistors. Above the breakdown voltage the voltage overshoot phenomenon effectively lengthens the turn-on time making the turn-off time smaller than the effective turn-on time. Below the breakdown voltage, slow decaying currents following the capacitance-charging peak discharging peak are found to show a power law temporal behavior, 1t to the nth power where n is very close to unity, over a time ranging from one microsecond to thousands of seconds after the beginningend of the applied voltage pulse. Activation energies of these transient currents were found to be approx. 10 meV and approx. 160 meV. We have provided a theoretical explanation of this time dependence tunneling from deep donors into the conduction band as the Fermi level is shifted down across the donor levels by the applied bias. A preliminary effort has been made to relate the cause of the voltage overshoot to the time needed for the depletion layer narrowing and hole creation.

Subject Categories:

  • Electrical and Electronic Equipment

Distribution Statement:

APPROVED FOR PUBLIC RELEASE