A study on the unipolar resistive switching of a CoO thin film shows that the compliance current (CC) has strong effects on the local structure of conducting filaments (CFs). Lower CCs produce CFs with simple connectivity and good controllability, resulting in a narrow distribution of switching voltages (SVs) and a high ratio of high-to-low resistance states. In contrast, the stronger net-like CFs are formed at higher CCs, and their complete rupture is difficult. Thus, the lower high-resistance states and a wide distribution of SVs appear in the reversible switching processes. Our results suggest that the generation of CFs with simple local structures is as important as the rupture process.

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