The effect of bottom LaB sub(6) electrode and La sub(2)O sub(3) interlayer on resistance switching in devices based on Li-doped ZnO films

Resistance switching (RS) characteristics of Al/ZnO:Li/LaB sub(6) and Al/ZnO:Li/La sub(2)O sub(3)/LaB sub(6) devices in which LaB sub(6) and lithium-doped ZnO (ZnO:Li) films are regarded as shallow work function metal and p-type semiconductor, respectively, are studied. The alternation from bistable unipolar memory switching (URS) to monostable threshold switching (MTS) in the Al/ZnO:Li/LaB sub(6) device is observed. These two switching behaviors can be activated separately depending on the polarity of applied dc voltage: with a positive polarity the URS behavior is measured, while the MTS behavior is observed with a negative polarity. With increase in the number of switching cycles, the MTS and URS behaviors irreversibly transform to bipolar resistance switching (BRS) behavior. The Al/ZnO:Li/La sub(2)O sub(3)/LaB sub(6) device shows only the BRS behavior, but after certain number of cycles device serves as a rectifying diode. On the basis of the I-V and C-V characteristics, it is concluded that RS properties depend on the barrier height and reactivity between LaB sub(6) metal and ZnO:Li oxide.