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| (a) Measured I-V patterns (sweep rate, 1 V/s) under various Icc. The arrows and the number in the graphs signify the switching direction. Similar responses were recorded by starting the sweeps from 0 V to |Vmax|(not shown here), confirming the completely forming free nature of our devices. (b) Evolution of the rectification ratio (RR) for the LRS and (c) dependence of both resistance states from the device area, under the application of a constant of Icc = 50 mA. |
ABSTRACT
Although multilevel capability is probably the most important property of resistive random access memory (RRAM) technology, it is vulnerable to reliability issues due to the stochastic nature of conducting filament (CF) creation. As a result, the various resistance states cannot be clearly distinguished, which leads to memory capacity failure. In this work, due to the gradual resistance switching pattern of TiO2−x-based RRAM devices, we demonstrate at least six resistance states with distinct memory margin and promising temporal variability. It is shown that the formation of small CFs with high density of oxygen vacancies enhances the uniformity of the switching characteristics in spite of the random nature of the switching effect. Insight into the origin of the gradual resistance modulation mechanisms is gained by the application of a trap-assisted-tunneling model together with numerical simulations of the filament formation physical processes.
Journal of Applied Physics:Investigating the origins of high multilevel resistive switching in forming free Ti/TiO2−x-based memory devices through experiments and simulationsP. Bousoulas, I. Giannopoulos, P. Asenov, I. Karageorgiou, and D. Tsoukalas
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