Reevaluation of the beneficial effect of Cu(In,Ga)Se2 grain boundaries using Kelvin probe force microscopy

Potential variations at grain boundaries are analyzed on the surface and on untreated cross sections of the absorber in a Cu(In,Ga)Se-2 solar cell applying Kelvin probe force microscopy. We observe three different types of potential variations between grain boundaries (dip-, step-, or peak-shape). The potential variations on cross sections are smaller than that on surfaces. Since the properties of grain boundaries on cross sections can be expected to resemble more closely the ones buried in the bulk as those on absorber surfaces, it is important to interpret functionalities of grain boundaries based on observations on cross sections. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4714905]