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Dielectric relaxation and Charge trapping characteristics study in Germanium based MOS devices with HfO2 /Dy2O3 gate stacks
In the present work we investigate the dielectric relaxation effects and
charge trapping characteristics of HfO2 /Dy2O3 gate stacks grown on Ge
substrates. The MOS devices have been subjected to constant voltage stress
(CVS) conditions at accumulation and show relaxation effects in the whole range
of applied stress voltages. Applied voltage polarities as well as thickness
dependence of the relaxation effects have been investigated. Charge trapping is
negligible at low stress fields while at higher fields (>4MV/cm) it becomes
significant. In addition, we give experimental evidence that in tandem with the
dielectric relaxation effect another mechanism- the so-called Maxwell-Wagner
instability- is present and affects the transient current during the
application of a CVS pulse. This instability is also found to be field
dependent thus resulting in a trapped charge which is negative at low stress
fields but changes to positive at higher fields.Comment: 27pages, 10 figures, 3 tables, regular journal contribution (accepted
in IEEE TED, Vol.50, issue 10
Mass transfer at low reynolds number in liquid fluidized beds
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