Contributions of acoustical deformation scattering, ion impurity scattering
and grain boundary potential scattering to the conductivity of TCO films h
ave been calculated in order to deduce the intrinsic limit of conductivity
of TCO films regardless of precise details of the preparation procedure. Th
e results indicate that the effective mass of charge carriers has a strong
dependence on carrier concentration. Based on the effective mass correction
, as well as the carrier concentration ionized impurity centre correction,
scattering due to ion impurity has been developed to explain the upper limi
t of mobility or the lower limit of resistivity of TCO films. Two empirical
expressions are introduced to depict the dependence of the upper limit of
mobility and the lower limit of resistivity of TCO films on carrier concent
ration. The dependence of transparency on carrier concentration is also dis
cussed.