Fig. 20
From: Status and Prospects of ZnO-Based Resistive Switching Memory Devices
a Three-dimensional AFM and b TEM images of one nanoisland; excluding the AFM tip effect, these characterizations show that the nanoislands are discrete and having sizes between 10 and 60 nm. c Schematic of ZnOnanoislands and a C-AFM tip used for measurements. d Threshold-like, e self-rectifying bipolar, and f ordinary bipolar I-V characteristics of a ZnOnanoisland at different current compliance. The nanoisland firstly underwent process (0) as indicated in d, i.e., a voltage sweep from 0 to 10 V under a current compliance of 5 nA. Then, the nanoisland underwent four voltage sweep processes sequentially (process (1): 5 to 0 V; process (2): 0 to 25 V; process (3): 25 to 0 V; process (4): 0 to 5 V) as illustrated in (d). Under the current compliance of 10 nA, 100 nA–10 mA, and 100 mA–1 mA, the voltage sweep processes resulted in three types of resistive switching (threshold-like, self-rectifying bipolar, and ordinary bipolar) in d, e, and f, respectively [78]