Non-volatile nano-floating gate memory with Pt-Fe2O3 composite nanoparticles and indium gallium zinc oxide channel

Non-volatile nano-floating gate memory characteristics with colloidal Pt-Fe2O3 composite nanoparticles with a mostly core–shell structure and indium gallium zinc oxide channel layer were investigated. The Pt-Fe2O3 nanoparticles were chemically synthesized through the preferential oxidation of Fe and subsequent pileup of Pt into the core in the colloidal solution. The uniformly assembled nanoparticles’ layer could be formed with a density of ~3 × 1011 cm−2 by a solution-based dip-coating process. The Pt core (~3 nm in diameter) and Fe2O3-shell (~6 nm in thickness) played the roles of the charge storage node and tunneling barrier, respectively. The device exhibited the hysteresis in current–voltage measurement with a threshold voltage shift of ~4.76 V by gate voltage sweeping to +30 V. It also showed the threshold shift of ~0.66 V after pulse programming at +20 V for 1 s with retention > ~65 % after 104 s. These results demonstrate the feasibility of using colloidal nanoparticles with core–shell structure as gate stacks of the charge storage node and tunneling dielectric for low-temperature and solution-based processed non-volatile memory devices.