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Published online by Cambridge University Press: 01 February 2011
The discovery of the steep increase of electrical conductivity in Porous Silicon (PS) samples in contact with Nitrogen Dioxide, NO2, opens the possibility to study the electrical conduction processes in nanostructured systems from a completely new point of view. The system undergoes a change of conductivity of 5 orders of magnitude when exposed to few ppm of NO2, whereas the free charge concentration increases by only one order of magnitude in the same pressure range. Upon NO2 exposure the system transition from an “insulator-like” to a “semiconductor-like” behaviour can be studied by means of several techniques. In this paper, the results from a Space Charge Limited Current (SCLC) study unambiguously demonstrate the change of the charging status of defects upon NO2exposure, and explain some “exotic” effects recently reported.