Investigating carrier transport paths in organic nonvolatile bistable memory by optical beam induced resistance change

The so-called optical beam induced resistance change (OBIRCH) method, a non-destructive characterization method, was adopted to investigate the spatial distribution of current transport paths in Au nanoparticle nonvolatile bistable memory devices. In scanning a laser beam to induce local changes of the temperature and the electronic/conduction properties, simultaneously the current change of the device (under the constant bias voltage) at each scanning step was recorded to visualize the distribution of the current conduction paths. The results reveal that in the memory devices using polymer-stabilized Au nanoparticles, the current transport paths during the writing mode or the subsequent reading mode (of the "on" state) are localized, and that once the localized current transport paths are established in the writing mode, the current transport in the subsequent reading mode (of the "on" state) would basically follow the same paths. The established conduction paths would be eliminated in the erasing process and be re-established in the next writing process. Yet, the current conduction paths established for the "on" state are somehow random and vary from writing to writing. Results of this work might have significant implications to operation or applications of such memory devices. This work demonstrates that the OBIRCH technique might be an useful method to characterize localized current transport paths in organic devices. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.