Fig. 1. (Color online) Structure and morphology characterization of as-synthesized product. (a) XRD pattern. (b) FESEM image.

Fig. 2. I–V characteristics of an individual SnO₂:Sm nanowire-based two-terminal device at 10 V bias voltage. (a) Typical I–V cyclic curve. The numbered arrows 1–6 indicate the direction of voltage sweeping. (b) 10 consecutive I–V cyclic curves, showing an excellent stability and repeatability.

Fig. 3. For the step (1) and (2) curve in Fig. 2(a), the fitted plot by FN tunneling mechanism.

Fig. 4. (Color online) Under only unidirectional voltage sweeping at a forward-biased bias from 0 to +10 V, I–V characteristics of an individual SnO₂:Sm nanowire-based two-terminal device. (a) One typical I–V cyclic curve. (b) 10 consecutive I–V cyclic curves.

Fig. 5. I–V characteristics measured at a relatively low bias voltage of 2 V. (a) One I–V cyclic curve. (b) Consecutive 80 I–V cyclic curves, showing a superior repeatability.

Fig. 6. (Color online) Memory properties of a single nanowire-based device. (a) 7 consecutive writing-reading-erasing-reading cycles, where +6.5, +10, and –10 V are selected as reading, writing and erasing voltage, respectively. (b) An enlargement of a dotted frame in (a).

Fig. 7. (Color online) Memory properties of a single nanowire-based device. (a) 7 consecutive writing-reading-erasing-reading cycles, where +7, +10, and –10 V are selected as reading, writing and erasing voltage, respectively. (b) An enlargement of a dotted frame in (a).

Fig. 8. (Color online) Under different pulse voltages, the response curves of the device current. (a) Consecutive pulse between +7 and +10 V. (b) Consecutive pulse between +7 and –10 V.

Fig. 9. (Color online) Stability of device current in LRS and HRS at a reading voltage of 6.5 V.