Size dependence of charge retention in gold-nanoparticles sandwiched between thin layers of titanium oxide and silicon oxide

Nonvolatile memory technology is a necessary component in many electronic devices. With the scaling down of memory devices to achieve high density and low power consumption, floating gate devices encounter various challenges like high leakage current, which leads to reliability issues and a decrease in charge density. Therefore, the use of metal nanoparticles (NPs) as charge storage centers is becoming a promising candidate due to their excellent scalability and favorable reliability. In this work, we demonstrate the charge storage dependency on the size of a gold-nanoparticle (Au-NP) by using a contact mode atomic force microscope. The individually dispersed Au-NPs are sandwiched between a thin layer (3 nm) of TiO₂ blocking layer and SiO₂ (2 nm) tunneling layer thin films. The consecutive I-V sweeps on a pristine device of stacking TiO₂/Au-NP/SiO₂/n-Si show that the threshold voltage (ΔV) increases with the increase in the Au-NP size, whereas the retention shows much more stability time with smaller size NPs, in the range of 10 nm.