Articles you may be interested inResistance switching behaviors of amorphous (ZrTiNi)Ox films for nonvolatile memory devices J. Vac. Sci. Technol. A 32, 061505 (2014); 10.1116/1.4896329 Effect of embedded metal nanocrystals on the resistive switching characteristics in NiN-based resistive random access memory cells J. Appl. Phys. 115, 094305 (2014); 10.1063/1.4867639Effect of Hf incorporation in solution-processed NiOx based resistive random access memory Appl. Phys. Lett.

We have fabricated and investigated the bipolar resistive switching characteristics of Pt/rutile-TiO2∕TiN devices for resistance memory applications. Data writing for five-level resistance states has been demonstrated by varying the amplitude of 5ns voltage pulses. In addition, data retention of more than 256h at 85°C and an excellent endurance of over 2×106cycles have been confirmed. These results indicate that Pt∕TiO2∕TiN devices have a potential for nonvolatile multiple-valued memory devices.

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We propose a parallel resistance model (PRM) in which total resistance (Rtotal) is given by the parallel connection of resistance of a filament (Rfila) and that of a film excluding the filament (Rexcl)—that is, 1/Rtotal = 1/Rfila + 1/Rexcl—to understand direct current (dc) electric properties of resistive random-access memory (ReRAM). To prove the validity of this model, the dependence of the resistance on temperature, R(T), and the relative standard deviation (RSD) of RHRS of Pt/NiO/Pt on the area of a top electrode, S, are investigated. It is clarified that both the R(T) and RSD depended on S, and all such dependencies can be explained by the PRM. The fact that Rtotal is decided by the magnitude relation between Rfila and Rexcl makes transport properties S-dependent and hinders the correct understanding of ReRAM. Smaller S is essential to observe the intrinsic transport properties of ReRAM filaments.

Ruthenium dioxide ( RuO2) thin films are evaluated as a bottom electrode for SrTiO3. It was found that a thin RuO2(50 nm)/Ru(20 nm) layer on Si is quite effective as a barrier layer for both orygen atoms and metals when depositing SrTiO3 at a relatively low temperature of 450° C. To test its suitability for high-temperature processes such as CVD of SrTiO3, the RuO2/Ru electrode on Si was annealed in air at 600° C for 1 hour. Even under this severe condition, the electrode using 100-nm-thick RuO2 was sufficient for preventing oxygen diffusion into Si.