Abstract
Indium–tin–oxide (ITO) is a transparent conductive
thin film that is widely used as a top conducive layer in photovoltaic solar
cells. However, ITO is sensitive to environmental conditions and the electrical
conductivity degrades as a consequence of harsh environmental conditions.
Furthermore, the thermal expansion coefficient mismatch between the ITO film
and the substrate creates stress/strain on the film when the package is subjected
to fluctuating temperatures. This could create micro-cracks and consequently
damage the film. Therefore, this study was designed to study the effect of
the thermal cycling and thermal aging on the ITO thin films to simulate the
effect of continuous high temperatures and fluctuating temperatures that may
be applied on the thin films during the usage. In this study, two sets of
experiments were conducted on a ${\hbox{60}}~\Omega/\square$ sputter-deposited ITO on ${\hbox{127}}~\mu{\hbox{m}}$ heat stabilized Poly Ethylene Terephthalate (PET) substrate. The
first set of experiments contained four samples which were thermally aged
at ${\hbox{100}}\ ^{\circ}{\hbox{C}}$ for 30 days and the other set of experiments contained another
four samples which were thermally cycled for 900 cycles. The thermal profile
consisted of a high temperature of ${\hbox{100}}\
^{\circ}{\hbox{C}}$, a low temperature of ${\hbox{0}}\ ^{\circ}{\hbox{C}}$, dwell
time of 10 minutes, and ramp rate of ${\hbox{10}}^{\circ}{\hbox{C}}/{\min}$, as depicted in Fig. 1 .
The initial results showed that the ITO thin film is not stable in the thermal
aging experiment and the electrical resistivity gradually increased for all
samples until the end of the 30 days. The degradation happened during the
thermal cycling as well. However, SEM images show that the morphology of the
ITO surface is stable under both conditions. Energy-dispersive X-ray (EDX)
spectroscopy analysis showed stability in the ITO thin film in terms of composition.
XRD spectra confirmed the improved crystallinity for the thermally aged films,
which corresponded to the increased transmission in the visible region.
© 2012 IEEE
PDF Article
More Like This
Cited By
You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.
Contact your librarian or system administrator
or
Login to access Optica Member Subscription
Add to BibSonomy