Damage-Free ALD Blocking Oxide Layer on Functionalized Graphene Nanosheets as Nonvolatile Memories

Abstract

In this brief, nonvolatile memory (NVM) devices, based on the capacitor structure with the graphene nanosheets (GNSs) as the discrete charge storage media and atomic-layer-deposited (ALD) Al2O3 dielectric as the blocking oxide (BO) layer, have been demonstrated. The GNSs are formed by using the gold (Au) nanoparticles as the self-aligned mask and functionalized by using the NH3 plasma to enrich the charge trapping centers. In addition, the ALD Al2O3 layer is adopted as the BO layer of the GNS NVMs, resulting in a damage-free deposition on GNSs, compared to the conventional chemical-vapor-deposited SiO2 layer. The GNS NVM devices with a 15-nm-thick ALD Al2O3 BO layer can exhibit an excellent endurance of more than 105 cycles and superior data retention of lower than 30% charge loss for 10 years, suitable for future NVM applications.