A memristor includes a first electrode of a nanoscale width; a second electrode of a nanoscale width; and an active region disposed between the first and second electrodes. The active region has a both a non-conducting portion and a source of dopants portion induced by electric field. The non-conducting portion comprises an electronically semiconducting or nominally insulating material and a weak ionic conductor switching material capable of carrying a species of dopants and transporting the dopants under an electric field. The non-conducting portion is in contact with the first electrode and the source of dopants portion is in contact with the second electrode. The second electrode comprises a metal reservoir for the dopants. A crossbar array comprising a plurality of the nanoscale switching devices is also provided. A process for making at least one nanoscale switching device is further provided.