Abstract Abstract – The AC electrical characterization of Au/porous silicon/p‐Si structure is presented. The low porosity porous silicon layers were prepared by electrochemical etching in p‐type silicon 〈100〉 with two resistivities. The AC electrical measurements capacitance–conductance–frequency were performed from 5 Hz to 10 MHz, at room temperature in the DC range of ±2 V. We studied two structures; first a conductor type Au/PS/Au and second diode type Au/PS/p‐Si/Al. We found the relationship between the bias voltage in the PS/p‐Si heterostructures with the depletion region formation and the conduction mechanism presents in these structures. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)