Charging and discharging characteristics of a single gold nanoparticle embedded in Al₂O₃ thin films

We demonstrate a metal-oxide-semiconductor based nonvolatile memory element structure with a single isolated gold nanoparticle (Au-NP) acting as the storage site. The Au-NPs are sandwiched between amorphous Al₂O₃ thin films, deposited using the atomic layer deposition method to form the blocking and tunneling layers. The current voltage characteristics of the fabricated structure during write/erase cycles are obtained using conductive mode atomic force microscopy (C-AFM) by probing a single isolated NP at a time. Consecutive voltage sweeps show a memory window in I–V characterization with an average of DV ~0.9 V at a reading current of 1.5 nA, demonstrating the presence of stored charge in the Au-NP, which originates from the AFM metal-coated probe. The results show the writing and erasing operation of the device by charging and discharging a single Au-NP. Moreover, the physics is discussed in terms of the electric field enhancement due to the charge confinement and its effect on the conduction mechanisms.