Analysis of Functional Oxide based Selectors for Cross-Point Memories

We present an extensive analysis of functional-oxide based selector devices for cross-point memories from the perspectives of materials through arrays. We describe the design constraints required for proper functionality of a cross-point array and translate these constraints to figures of merit for the selector materials. The proposed figures of merit, related to the resistivities of the functional oxide in the metallic and insulating states and the critical current densities for insulatormetal transitions, determine whether or not a functional oxide is suitable to be employed as a selector for a memory technology. Our analysis shows the importance of co-optimizing the selector length with the read/ write voltages and establishes the range of these parameters for proper functionality. We also perform an extensive material space analysis for the selector, relating the selector properties to the achievable array metrics. For instance, we show that optimized memory array with single crystal VO2 based selector and spin-memory element achieves similar to 25 mu A sense margin with similar to 30% read disturb margin and 40ns write time. The leakage in the half-accessed cell can be as low as 15 mu W. The design principles established in this work will provide guidelines for future exploration of functional oxides for selector applications as well as for the optimization of cross-point arrays.