Integration of ammonia-plasma-functionalized graphene nanodiscs as charge trapping centers for nonvolatile memory applications

Graphene nanodiscs (GNDs), functionalized using NH₃ plasma, as charge trapping sites (CTSs) for non-volatile memory applications have been investigated in this study. The fabrication process relies on the patterning of Au nanoparticles (Au-NPs), whose thicknesses are tuned to adjust the GND density and size upon etching. A GND density as high as 8 × 10¹¹ cm⁻² and a diameter of approximately 20 nm are achieved. The functionalization of GNDs by NH₃ plasma creates N[sbnd]H⁺ functional groups that act as CTSs, as observed by Raman and Fourier transform infrared spectroscopy. This inherently enhances the density of CTSs in the GNDs, as a result, the memory window becomes more than 2.4 V and remains stable after 10⁴ operating cycles. The charge loss is less than 10% for a 10-year data retention testing, making this low-temperature process suitable for low-cost non-volatile memory applications on flexible substrates.