Abstract

Memristors with various switching characteristics could realise low-power reconfigurable electronics. This paper reports the coexistence of nonvolatile and volatile switching characteristics in Ag/Ti/ZnO/TiN CBRAM memristor devices and examines the feasibility of the cycle-to-cycle fluctuation of both characteristics for memory and random number generator (RNG) applications. A circuit design exploiting the nonuniformity to produce random bits is proposed. We show that random bits can be produced by the circuit regardless of the nonvolatile switching characteristics; nevertheless, volatile behavior may be preferred for low-power operation. Nonvolatile-tovolatile switching transformation can be achieved by inserting an excessively thick barrier layer or applying a low current compliance to form a metastable conducting bridge. We found a close correlation between the statistical distribution of the switching nonuniformity and the randomness parameter for making reliable random bits.