Nonvolatile memory properties of Pt nanoparticle-embedded TiO₂ nanocomposite multilayers via electrostatic layer-by-layer assembly

It is demonstrated that notable resistive switching memory properties depending on voltage polarity (i.e. bipolar switching properties) can be obtained from the layer-by-layer (LbL) assembled multilayers based on transition metal oxides and metal nanoparticles. Cationic poly(allylamine hydrochloride) and anionic titania precursor layers were deposited alternately onto Pt-coated Si substrates using an electrostatic LbL assembly process. Anionic Pt nanoparticles (Pt_NP) with about 5.8nm diameter size were also inserted within the multilayers using the same interactions mentioned above. These multilayers were converted to Pt_NP-embedded TiO₂ films by thermal annealing and the films were then coated with a top electrode. When external bias was applied to the devices, bipolar switching properties were observed at low operating voltages showing the high ON/OFF ratio (>10 ⁴) and the stable device performance. These phenomena were caused by the presence of Pt_NP inserted within TMO films.