The electrical properties of Cu-doped CdTe films sintered with or without flux were investigated.
The experimental results showed a trend that the hole concentration increased and then decreased with the increasing amount of CuCl added.
It was thought that the decrease in the hole concentration with CuCl was caused by the self-compensation and association of Cu because of its amphoteric property.
For the films sintered without flux, the carrier mobility decreased monotonously with the amount of CuCl added, probably due to the remained CuCl after sintering.
For the films sintered with flux, the carrier mobility increased monotonously with the amount of CuCl, probably due to the increase of grain size and the precipitation of the conducting phases at the grain boundaries or at some other lattice defects.
The combination of the carrier concentrations and mobilities resulted in the minimization of the film resistivity at about $10^{-2}$ m/o CuCl.