Environmental Engineering Reference
In-Depth Information
Figure 9.11
Sudden discontinuities and kinks observed in I-V curves,
showing the Fermi-level changes from one position to another, producing
different I-V characteristics corresponding to different
φ
b
values.
Figure 9.8(a) represents a clear example of the reduction of
V
oc
as a result of forward biasing and the reversal to the original value
after reverse biasing. With further forward biasing, this particular
diode (0.5 mm diameter) shows stable behaviour after this first
variation, indicating a permanent change such as a removal (or
passivation) of temporary defects existing at the interface. These
types of temporary defects may arise due to trapped charges at the
interface. On the other hand, the diode shown by Fig. 9.8(b) shows
reversible behaviour. A forward bias reduces
V
oc
,andareverse
bias restores the value to original figures, with
V
oc
again reducing
after further forward biasing. This behaviour seems reversible for
this diode, indicating the presence of a set of permanent defect
structures at the interface.
