Figure 4 (a), (b) dV/d(lnI) versus I for
a-Si:H(i)/MoOx/Ag and
a-Si:H(i)/MoOx/ICO/Ag stacks with different electrode
diameters. The arrow direction represents the electrode diameter
decreasing. (c), (d) (RT-RS) versus
4/(πd2) and the corresponding linear fitting curve.
Two stacks with the architectures of
c-Si(p)/a-Si:H(i)/MoOx/Ag and
c-Si(p)/a-Si:H(i)/MoOx/ICO/Ag were prepared for contact
resistance measurement. The measurement and fitting results were
depicted in Fig. 4. The calculated ρc of the
c-Si(p)/a-Si:H(i)/MoOx/Ag stack and the
c-Si(p)/a-Si:H(i)/MoOx/ICO/Ag stack is 213.94
mΩ·cm2 and 191.28 mΩ·cm2,
respectively. It is worth noting that Rc contains
not only the contact resistance between MoOx and ICO,
but the one between MoOx and c-Si(p), and also the bulk
resistances of each film layers. As far as the investigated two stacks,
there architectures are the same except for the ICO layer. So the
difference in ρc should come from the contact resistance
of MoOx/TCO and MoOx/Ag. As a
conclusion, in addition to improving long wavelength response as
discussed previously, adding ICO between the MoOx and
the Ag electrode can reduce the contact resistance as well.