Apr 4, 2014
A new conceptual structure for high-density memory applications
Resistive random access memory (RRAM)-based cross-point arrays have excellent scalability and 3D integration at high density. A hindrance to practical memory applications, however, is the issue of cross-talk. Now, reporting in Nanotechnology, researchers have proposed a new conceptual structure to counteract this.
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.
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.
About the author
Yingtao Li is currently a faculty member at the School of Physical Science and Technology, Lanzhou University in China. His current research interests include semiconductor materials, fabrication and integration of emerging nonvolatile RRAM devices.