Gadolinium oxide nanocrystal nonvolatile memory with HfO₂/Al₂O₃ nanostructure tunneling layers

In this study, Gd₂O₃nanocrystal (Gd₂O₃-NC) memories with nanostructure tunneling layers are fabricated to examine their performance. A higher programming speed for Gd₂O₃-NC memories with nanostructure tunneling layers is obtained when compared with that of memories using a single tunneling layer. A longer data retention (<15% charge loss after 10⁴s) is also observed. This is due to the increased physical thickness of the nanostructure tunneling layer. The activation energy of charge loss at different temperatures is estimated. The higher activation energy value (0.13 to 0.17 eV) observed at the initial charge loss stage is attributed to the thermionic emission mechanism, while the lower one (0.07 to 0.08 eV) observed at the later charge loss stage is attributed to the direct tunneling mechanism. Gd₂O₃-NC memories with nanostructure tunneling layers can be operated without degradation over several operation cycles. Such NC structures could potentially be used in future nonvolatile memory applications.