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 ΔV ∼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.