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Hydrogenated nanocrystalline silicon (nc-Si:H) is a multiphase, heterogeneous material, composed of Si nanocrystals embedded in an amorphous matrix. It has been intensively studied in the last few years due to its great promise for photovoltaic and optoelectronics applications. The present paper aims to study the current transport mechanisms in nc-Si:H by mapping the local conductivity at the nanoscale. The role of B doping in nc-Si:H is also investigated. Conductivity maps are obtained by atomic force microscopy using a conductive tip. Differences and similarities between intrinsic and doped nc-Si:H conductivity maps were observed and these are also explained on the basis of recently published computational studies. [ABSTRACT FROM AUTHOR]

Conductive atomic force microscopy (C-AFM) has been extensively used for making measurements of electrical properties of nanostructures, devices and multiphase materials. Despite its wide use, the mechanical and electrical interactions at the nanoscale between the tip and the sample surface are not yet well understood. These phenomena should be carefully studied and modeled in order to avoid significant measurement artifacts. In the present contribution a study of the interactions occurring between conductive tips and the surface of nanocrystalline silicon thin films that lead to measurement artifacts is presented. A significant deterioration of the tip coating was detected after a few maps, resulting in meaningless maps. The features of the map obtained dramatically depend on the tip coating characteristics and on the load conditions. Moreover, under a constant bias voltage, the electrical current passing through the tip-sample junction degenerates strongly with time. These phenomena were interpreted by considering the effect of strong electric fields present during C-AFM experiments.