Most oxides grown by ALD technique at 300°C are normally amorphous. In this study, the process temperature is 300°C, while the crystallized temperatures of Nb2O5 and Al2O3 are both above 400°C. The chemical compositions of NbAlO films were shown in Figure 2. Figure 2a presents the Al 2p spectrum of the film.

The peak position is found to be at the 74.4 eV, which indicates that Al tends to be oxidized. The Nb 3d spectra can be divided into two edge splits: Nb 3d 3/2 and Nb 3d 5/2. The Nb 3d 3/2 and 3d5/2 peaks are located at 210.2 eV for Nb2O5[9] and 207.5 eV for NbO2[10]. Figure 3 shows the typical bipolar resistive switching characteristics of NbAlO films at temperatures 80 buy Obeticholic Acid to 200 K. By sweeping the positive voltage above a certain value (1.5 to 3 V), an abrupt current increase occurs, indicating the film in LRS. It means that the so-called SET process occurs. There is no obvious difference after more than 1,000 cycles for the current–voltage Selleckchem Caspase inhibitor switching behavior from 80 to 200 K, as shown in Figure 3. It suggests that the conductive filaments statistically formed in the SET process have the same density, diameter, and current conduction. Hence, the difference in RESET current and energy consumption cannot be as ascribed to the

random variation of uncertain conductive filament formation. In other words, the effect of SET process on the RESET difference can be safely excluded. Meanwhile, current–voltage

curves after the RESET process in many cycles also keep the same route, indicative of the high repeatability of RESET characteristics of the NbAlO film, which facilitates our quantitative calculation and simulation of the process in the following research. To clarify this difference and to understand the mechanism of the RESET process, we consider the RESET from an energy point of view combined with joule heat-induced interface thermal reaction [7] and charge trap/detrapping effect [11–14]. Figure 1 The cross-sectional TEM image of NbAlO film. most Figure 2 The XPS spectra of NbAlO film chemical composition. (a) The Al 2p peak shows the Al2O3 and (b) the Nb 3d 3/2 and 3d 5/2 peaks show the Nb2O5 and NbO2, respectively. The B.E. means binding energy in x-axis. Figure 3 The typical resistive switching current–voltage curve of NbAlO-based RRAM device at different environmental temperatures. (a) 80, (b) 120, (c) 160, and (d) 200 K. The inset in (c) shows the schematic diagram of measured device structure and configuration. The I-V curve in different color indicates different resistive switching cycles. Figure 4 shows the statistical results of the typical electrical parameters of RRAM obtained at different temperatures. The LRS resistance, RESET voltage, and RESET current value distribution are shown in Figures 4a,b,c, respectively.