Conductivity mapping of nanoparticles by torsional resonance tunneling atomic force microscopy

In this paper, torsional resonance tunneling mode atomic force microscopy is used to study the conductivity of nanoparticles. SnS nanoparticles capped with trioctylphosphine oxide (TOPO) and with In2S3 shell are analyzed. This contactless technique allows carrying out measurements on nanoparticles without destroying them and to obtain simultaneously topography and conductivity maps. This made it possible to achieve complete characterization of individual particles in a single measurement. The results demonstrate that the particles have conductive properties. The results have also showed that the TOPO capping layer may hinder tunneling currents, therefore should be avoided when performing these measurements.