Charge storage in metal-chalcogenide bilayer junctions

Abstract

We demonstrate that electrical charges are stored in the bilayer junctions of Al and Bi–Cu–S alloys. The junctions exhibit interfacial resistance switching, which is caused by a spontaneous production of high resistivity compounds at the interface and their electrochemical dissolution under a voltage bias. The charge storage results from the redox reactions that are responsible for the resistance switching. In contrast to conventional secondary batteries, the storing capability increases as the temperature is lowered from room temperature to 77 K, where the charges are released in a time scale nearly on the order of hours. The charging and discharging are thereby indicated not to rely on ionic transport. The battery effect is reversible in polarity. Storage characteristics are modified when Cu in the ternary alloy is replaced with Ag or Ni in a similar manner to the way the properties of the interfacial resistance switching are altered.