Memory effects of carbon nanotubes as charge storage nodes for floating gate memory applications

Abstract

A nonvolatile flash memory device has been fabricated using carbon nanotubes (CNTs) as a floating gate embedded in HfAlO (the atomic ratio of Hf/Al is 1:2) high-k tunneling/control oxides and its memory effect has been observed. Capacitance-voltage (C-V) measurements illustrated a 400 mV memory window during the double C-V sweep from 3 to −3 V performed at room temperature and 1 MHz. Further studies on their programming characteristics revealed that electron is difficult to be written into the CNTs and the memory effect of the structures is mainly due to the holes traps. The memory window width can remain nearly unchanged even after 10⁴ s stressing, indicating excellent long term charge retention characteristics. We therefore suggest that the CNTs embedded in HfAlO can be potentially applied to floating gate flash memory devices.