This suggests that the conduction mechanism for both LRS and HRS is trap-controlled space charge-limited current conduction click here mechanism (TC-SCLC). The switching mechanism is based on the formation and rupture of the conducting filament at the IrO x (TE)/GdO x interface, depending upon the electrical bias. By applying negative bias on the TE of the IrO x /GdO x /W via-hole devices, the O2– ions drift toward the W BE and partially oxidize, as well as sink into the W BE. Due to the presence of huge numbers of PD173074 manufacturer oxygen vacancies into the GdO x layer, there is much possibility to form multiple filaments resulting in non-uniform resistive switching. This

phenomenon was also observed for IrO x /TaO x /W structure [46]. By applying positive bias on the IrO x /GdO x /W via-hole devices, the O2– ions migrate Selleck Dorsomorphin toward the IrO x TE. Due to the porous nature of IrO x , some O2– ions drift out and some oxygen are gathered at the IrO x /GdO x interface. The porous IrO x film was also reported recently [47]. Oxygen-rich GdO x layer

at the GdO x /TE interface acts as a series resistance which restricts the overshoot current and makes the filament uniform. This interfacial series resistance helps achieve a repeatable switching cycle; however, few devices are controllable. On the other hand, a cross-point memory device does not exhibit switching under negative bias on the IrO x TE, owing to higher resistivity of thinner IrO x TE, and the device cannot reach a higher operating current. However, the cross-point memory device exhibits excellent resistive switching characteristics under positive bias on the IrO x TE due to both the rough surface of the W BE and oxygen

gathering at the IrO x /GdO x interface. The electric field enhancement on the nanotips of the W BE and the interfacial series resistance of IrO x /GdO x with thinner layer IrO x TE help the structure have controllable resistive switching characteristics. Owing to the structural shape and the W BE surface differences, the cross-point memory devices have low-positive-voltage format, repeatable switching cycles, and self-compliance, and have improved switching characteristics than the via-hole devices. The similar phenomena was also reported recently [48]. However, further study is ongoing to understand the different resistive switching characteristics between the via-hole and cross-point Thymidylate synthase memory devices. To check the uniformity of the cross-point memory devices, the statistical distribution of IRS, HRS, and LRS were randomly measured in more than 20 devices, as shown in Figure 8. Some devices are not switchable, which may be due to process variation from our deposition system. Most of the memory devices exhibit good distribution of IRS, HRS, and LRS. The average values (σ m) of IRS, HRS, and LRS are found to be 29.44G Ω, 9.57 MΩ, and 14.87 kΩ, and those values for standard deviation (σ s) are 89.47, 7.21, and 6.67, respectively.