(a) Typical I-V characteristics of Cu/GeO x /W and (b) Al/GeO x /W www.selleckchem.com/products/iwr-1-endo.html cross-point memories. Figure 5 Current–voltage characteristics. I-V measurements of pristine (a) Cu/GeO x /W (S1) and (b) Al/GeO x /W (S2) devices. A high formation voltage is needed for Al TE. More than eight devices were measured randomly. Further, the RESET current is independent of CCs from 1 nA to 1 mA for the Al/GeO x /W cross-point memory device, as shown in Figure  6. This suggests that the RESET current scalability as well as device scaling is difficult for the Al TE devices, which form larger filament diameter (or many conducting filaments) even at a small CC of 1 nA. This is due to a strong current overshoot

effect in the Al/GeO x /W cross-point memory devices. It is noted that the

diameters of the conducting filaments are the same at all CCs from 1 nA to 2 mA, which is due to the defective AlO x layer this website at the Al/GeO x interface or unstable interface. Selleckchem TPCA-1 A high RESET current of >20 mA was also reported by Kato et al. using Al TE [44]. Lin et al. [12] also reported a high RESET current for Al2O3-based resistive switching memory using a Ti/Al2O3/Pt structure. According to several reported results, using Al electrode or Al2O3-based resistive memory devices requires higher operation voltages as well as high RESET currents [12, 44, 45]; however, a few results were reported on low-current operation [6–8, 14]. As we can see, the formation voltage of the Al/GeO x /W device is higher

than that of the Cu/GeO x /W device. It seems that the parasitic capacitance [46] of the Al/GeO x /W device as well as the current overshoot effect is higher. Even if the SET voltage is lower, the RESET current is still very high or the same with the RESET current of formation. This suggests that the current overshoot effect is not due to the higher operation voltage but to the AlO x formation at the Al/GeO x interface or unstable interface. This is a very important difference between these Al and Cu TEs. An excellent scaling of the RESET current is observed for the Cu/GeO x /W cross-point memory devices with CCs from 1 nA to 50 μA. Furthermore, the RESET current is lower than the SET current, which proves no current overshoot effect PRKACG even in the 1R configuration or no parasitic effect [46]. The formation and dissolution of Cu nanofilament under SET and RESET are responsible for the switching mechanism of the Cu/GeO x /W cross-point memory devices. The Cu ions will migrate through the defects into the GeO x film and start to grow first at the GeO x /W BE under SET operation by reduction process (Cu z+ + ze- → Cuo). The Cu nanofilament will start to dissolve at the Cu/GeO x interface under RESET operation by oxidation process (Cuo → Cu z+ + ze-). In the case of the Al/GeO x /W cross-point memory, oxygen vacancy filament formation and oxidation are responsible for the switching mechanism.