Abstracts Book - IMRC 2018

• SA6-P010
QUANTITATIVE INVESTIGATION OF PYROELECTRIC
LUMINESCENCE THROUGH POOLE-FRENKEL EFFECT
Mohamed Swaisi 1 , Andreas Ruediger 1 , Membarka Atantawi 1
1 Université du Québec, Energy and Materials Sciences, Canada.
Pyroelectric luminescence refer to a faint emission of light materials with
spontaneous polariztion. Contrary to thermally stimulated luminescence, it is
not directly thermally activated and might also occur upon cooling. Depending
on the ambient pressure, two different types of emission have been reported.
Under ambient pressure and moderate vacuum condition, electric discharges
through the ambient gas dominate the emission and provide short circuit
conditions, for the electric field across the sample with every discharge. Under
high vacuum conditions,these discharges cease while a more continuous
emission can be observed. This emission, while being reported in almost all
pyroelectrics, has so far not been explained. We invoke the Poole-Frenkel effect,
a field mediated lowering of the coulomb barrier, in deep traps as the origin of
the observed phenomena, bearing in mind that even field emission might occur
for very large fields. Our model qualitatively accounts for all observations
related to this type of pyroelectric luminescence, in particlar the dynamics and
the sensitivity to phase transitions. Our model, while being quantitative, is
challenged through the requirement of having a complete temperature
dependence for a large number of material parameters across the observed
temperature range 77K to 500K. The pyroelectric coefficient, the static
permittivity, the refractive index, and the dark conuctivity. The key experimental
parameters are the excitation wavelenght to fill the defect states at low
temperature, the ambient pressure as well as the heating or cooling rate. Our
presentation will conclude with set of inequalities defining the parameter space
for which this type of emission can be observed as well as with a tentaive model
to extract activation energies of deep traps that are otherwise inaccessible to
thermal ionizations. This work has been supported through a scholarship of the
Libyan goverment and an NSERC discovery grant(A.R)
Keywords: TSL, SPEL, POOLE-FRENKE MODEL
Presenting authors email: sweesymohamed@gmail.coms