Environmental Engineering Reference
In-Depth Information
(a)
(b)
Figure 9.7
Sudden discontinuities and completely distorted I-V curves
observed during measurements after the application of external electrical
stresses to diodes and then removed.
measurement cycle or during the application of electrical stresses,
the Fermi level could switch onto different positions, producing
diodes of different barrier heights. These device structures with
numerous defect levels at their interfaces, therefore, could produce
different I-V characteristics, depending on the immediate history
of the device. Some of the possible different I-V curves are shown
with dotted lines in Fig. 9.11 with different potential barriers.
During the switch-over from one I-V curve to another, peculiar
kinks and sudden discontinuities could occur, as shown in the
diagrams. These kinks and discontinuities could appear at different
positions depending on the defect structures, defect densities, and
their electron occupation.
Since this diode has two interfaces with complex defect
structures, the Fermi level crosses defect levels on both interfaces.
