Exploring the switching nonuniformity of CBRAM for random number generators

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.