Ambipolar carrier injection of gold nanocrystal nonvolatile memory with different tunneling oxide thickness

Ambipolar carrier injection and charge retention phenomenon of gold-nanocrystal (Au-NC) memories with different tunneling oxide (TO) thickness were investigated. For the samples with thin TO (~3 nm), the electrons were injected from the substrate at positive gate bias. With the increase of TO thickness, the holes injected from the gate became more significant. Compared with the gate injected holes in the sample with thick TO, the substrate injected electrons in the sample with thin TO show a higher charge loss. The poor charge retention can be ascribed to the direct tunneling leakage current through the thin TO. Further, the Au-NC memories with electrons exhibit lower activation energy of charge loss than that with holes, which is due to the lower electron barrier height of the Au-NC memory.