Cross-talk causes the misreading of the high resistance state (HRS) due to leakage current paths through neighbouring cells with a low resistance state (LRS). To avoid this and achieve a reliable high-density crossbar array, a variety of device concepts and structures have been previously proposed to address the sneak path problem in RRAM-based crossbar arrays. For example, the one-transistor one-resistor (1T1R) structure, the complementary resistive switch (CRS) structure and building intrinsic diode characteristics into the RRAM cells.

Here, researchers from Lanzhou University in China, propose a new conceptual structure consisting of two anti-parallel-connected diodes as a bipolar RRAM selector and one RRAM cell (2D1R) for high-density bipolar RRAM crossbar array applications.

Suppressing the sneak current

Both the simulation and experiment are performed utilizing two anti-parallel-connected diodes and a bipolar RRAM cell connected in series with the anti-parallel-connected diodes as the selector for the bipolar RRAM. By using the anti-parallel-connected diodes as a bipolar selector, highly nonlinear I-V characteristics can be realized for suppressing the undesired sneak current in the crossbar array. Experimental results show that sneak current can be effectively suppressed by adding the anti-parallel-connected diodes as the bipolar selector.

High-density memory

At the maximum array size of the 2D1R-based crossbar array, more than 1 Mb is realized at a readout margin of 10% as estimated by the 1/2Vread voltage scheme. These results indicate that the anti-parallel-connected diodes have great potential for use as a selector for high-density bipolar RRAM crossbar array applications.

More information about the research can be found in the journal Nanotechnology 25 185201.

Further reading

Controlled quantum conductance in resistive switches highlights opportunity for atomic-scale memory (Mar 2012)
Non-destructive readout for complementary resistive switches (Oct 2011)