Figure signaling pathway 3a indicates that the overall resistance of the WO3 nanowire decreases firstly, and then increases unconventionally with increasing temperature. It also indicates that these I-V curves become more nonlinear and asymmetric at elevated temperature, and the differential resistance even becomes negative in two bias ranges (near −1 and 0 V when swept from −1 to +1 V). The WO3 nanowire device with asymmetric contacts demonstrates good rectifying characteristic when the temperature reaches

425 K. Figure 3 I – V curves recorded for WO 3 nanowire with asymmetric contacts. (a) I-V curves recorded for an individual WO3 nanowire (with a diameter of 100 nm) with asymmetric contacts between the two ends of the nanowire and electrodes under different temperatures in vacuum. Inset in the upper left corner is a SEM image of the WO3 nanowire with asymmetric contacts. Inset in the lower right corner shows the I-V curve recorded within a small sweep range near zero bias. (b) I-V curves recorded for the WO3 nanowire with different bias sweep rates at 425 K. Inset shows the close view of the I-V curves near zero-bias. In order to investigate the memristive electrical switch in more detail, I-V curve was recorded at 425 K under different bias sweep rates. As shown in Figure 3b, the shape of the hysteresis

loop exhibits a significant dependence on the bias sweep rate. buy ARRY-438162 As the sweep rate is decreased, the current will increase or decrease more quickly with bias voltage in the negative bias region, and the width of the hysteresis in bias voltage will decrease noticeably. Moreover, the current under large negative bias will increase

remarkably, while the bias range with negative differential resistance (near −1 V) will also decrease correspondingly. The inset in Figure 3b shows the close Cediranib (AZD2171) view of the I-V curves near zero-bias, which indicates that the electric current increases at first, and then decreases quickly to near zero as the bias voltage is increased. It also indicates that the switch from low resistance state to high resistance state is more quickly, and the switch can be triggered by an even smaller bias voltage when the sweep rate is slowed down. These results suggest that the time scale of the memristive electrical switch might be comparable to that of bias sweep. Generally, more electrons are thermally activated with increasing temperature, and the electron and hole quasi-Fermi level of the WO3 nanowire will rise up and lower respectively, which might alter electronic structures of the junctions between the WO3 nanowire and electrodes and then lead to nonlinearity and hysteresis in I-V curves MEK inhibitor discussed above.