Fabrication and Characteristics of Nano-Floating Gate Memories with ZnO Nano-Crystals as Charge-Storage Layer

Nano-floating gate memory devices with ZnO nano-crystals as charge storage layers are fabricated, and the influence of post-deposition annealing temperature and thickness of the ZnO layer are investigated. Atomic force microscopy and scanning electron microscopy reveal the morphology of discrete ZnO nano-crystals. For capacitance-voltage measurements, it is found that the memory device with 1.5 nm ZnO and annealed at 700^\circ\!C shows a larger memory window of 4.3 V (at \pm6 V) and better retention characteristics than memory devices with 2.5 nm ZnO or annealed at other temperatures. These results indicate that the nano-floating gate memory with ZnO nano-crystals can obtain good trade-off memory properties.