Bending effect on resistive switching behavior of HfO2/NiO p-n heterojunction

The HfO2/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 10(3). 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 HfO2, the NiO/HfO2 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. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

The HfO2/NiO nanocomposite films were fabricated using a sol-gel spin-coating method to investigate the bending effect on resistive switching of p-n heterojunctions, showing reliable bipolar switching performance with a decrease in on/off ratio after bending. Finite element studies identified channel cracks and delamination as main fatigue damage sources, affecting the resistance switching. The different mechanical properties of NiO and HfO2 at the p-n interface may help restrain crack propagation and improve anti-bending properties. Numerical calculations indicated a drastic fatigue-life drop above a threshold stress of 300 Mpa due to interfacial delamination and increased crack spacing.