| AVS 62nd International Symposium & Exhibition | |
| Atom Probe Tomography Focus Topic | Monday Sessions |
| Session AP+AS+MC+MI+NS-MoM |
| Session: | Atom Probe Tomography of Nanomaterials |
| Presenter: | C.-G Park, Pohang University of Science and Technology (POSTECH), National Institute for Nanomaterials Technology (NINT), Republic of Korea |
| Authors: | J.-H. Lee, Pohang University of Science and Technology (POSTECH), Samsung Electronics, Republic of Korea J.-B. Seol, Pohang University of Science and Technology (POSTECH), National Institute for Nanomaterials Technology (NINT), Republic of Korea C.-G. Park, Pohang University of Science and Technology (POSTECH), National Institute for Nanomaterials Technology (NINT), Republic of Korea |
| Correspondent: | Click to Email |
Threshold switching is the basis of electrical or thermal-driven phase change mechanism of oxide layer. That is, some oxide can change their conductivity from the level of insulators to that of metals with above certain current density. Although the mechanism responsible for threshold switching is not fully understood at present, it can be used as a switching device for the solution of sneak leakage problem. In order to apply the bipolar switching materials as the active layer of Resistive-switching Random Access Memory (RRAM), selection device which can minimize the sneak leakage current is needed. Among various candidates, we chose Nb-oxide for the selection device due to its superior compatibility with semiconductor structure. We have elucidated the mechanism of threshold switching of the amorphous NbO2 layer by using in-situ transmission electron microscopy (TEM) technique combined with atom probe tomography (APT).
In this study, we proved that through an ex-situ experiment using TEM the threshold switching of amorphous NbO2 accompanies local crystallization. The change in I-V characteristics after electroforming was examined by evaluating the concentration profile. APT combined with in-situ TEM probing technique was performed to understand the threshold switching in amorphous NbO2. The local crystallization in amorphous NbO2 was validated by the observed difference in time-of-flight (ToF) between amorphous and crystalline NbO2. We concluded that the slower ToF of amorphous NbO2 (a-NbO2) compared to that of crystalline NbO2 (c-NbO2) is due to the resistivity difference and trap-assisted recombination.