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To investigate how the p−n interface affects the resistive switching, we studied bilayer and nanocomposite films composed of p−type NiO and n−type CeO 2 . The samples were fabricated on ITO substrate by sol−gel spin coating. The current-voltage curves were measured with GaIn liquid top electrode, which exhibit reversible bipolar resistive switching with the maximum ON/OFF ratio of ∼10 3 at a read voltage of +0.5 V. The ON/OFF ratio of bilayer samples is three times improved than that of the nanocomposite film. This is ascribed to the larger depletion width in bilayer film than that of the nanocomposite one. We show that the p−n structure plays a key role in the formation/rupture of filamentary paths due to different depletion interfaces of the films. [ABSTRACT FROM AUTHOR]

The HfO 2 /NiO nanocomposite films are fabricated by sol-gel spin-coating method to investigate the bending effect on resistive switching of p-n heterojunction. Reliable bipolar switching performance is obtained with on/off ratio over 103. Upon bending times over 2000, the device on/off ratio is deteriorated about one order of magnitude. The finite element studies show that the main fatigue damage includes channel cracks and active−layer/ITO delamination. The switching process is described by the formation and rupture of oxygen vacancy filaments at the p–n interface, which may be partially cut by the cracks leading to the degradation of resistance switching. Owing to different mechanical properties of NiO and HfO 2 , the NiO/HfO 2 p-n interface may restrain crack propagation to some extent and thus ameliorate the anti-bending properties. The numerical calculation of fatigue life further indicates that the devices suffer from a drastic fatigue−life drop above threshold stress of 300 Mpa as a result of both interfacial delamination and the increase of crack spacing inside of the grain interior. Our work may provide some insights into studying how to improve switching performance of p-n heterojunctions under mechanical stimuli. • Switching mechanism dominated by oxygen vacancy filament at HfO 2 /NiO p–n interface • Bending−induced internal stress encourages crack formation and memory degradation • HfO 2 /NiO p-n interface hinders crack propagation and ameliorates fatigue tolerance [ABSTRACT FROM AUTHOR]