Maxwell-Wagner polarization in Cu(In,Ga)(S,Se)2

We give experimental evidence of Maxwell-Wagner polarization within Cu(In,Ga)(S,Se)2 and CuInSe2, which is caused by inhomogeneity. The transport of charge carriers is quantitatively described by a percolation network of capacitive and resistive pathways, where the transmissibility of the latter depends on voltage and is strongly narrowed down with decreasing temperature. Additionally, we find that leakage currents through barrier layers with a linkage to inhomogeneous semiconductors may significantly convey a phase-shifted component that gives information on the interface. The finding of percolative charge transport strongly questions results of standard characterization methods, which assume regular charge transport in inhomogeneous semiconductors.