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In this research, we investigate an electroforming and electrically driven insulator-metal transition (E-IMT) characteristic of the NbOx film that follows the framework of nucleation theory. First, we carry out the electroforming process to form the crystalline NbO2 phase, and it separated to nucleation and grain-growth according to external electric field degree. During the electroforming process, we also study the field-induced nucleation that occurred selectively according to the crystallinity of films. We conclude that the E-IMT process was the result of Peierls transition between the tetragonal and the rutile NbO2 phases, and we experimentally deduce the minimum energy pathway for transition. [ABSTRACT FROM AUTHOR]

The development of selector devices is essential for the implementation of dense memory arrays. Ovonic threshold switch (OTS) devices have gained interest as high‐performance selectors, but their material complexity and low thermal stability remain concerns. The effect of element compositions and its types on binary telluride‐based OTS are investigated to develop selectors that meet the simple material composition and high thermal stability requirements while ensuring low OFF‐state leakage current (IOFF). Through a careful control of Te composition in binary tellurides, binary OTS devices with low IOFF (≈5 nA) and fast switching speed (<10 ns) are obtained. In addition, high endurance (108) and thermal stability (450 °C) are achieved by adopting tellurides including small elements. The high thermal stability of the developed OTS devices results from the strong covalent bonds between Te and small elements that prevent crystallization of the tellurides, which is revealed by performing first‐principles calculations. The binary OTS are also compatible with a 3D stacking technology, which is confirmed by fabricating a 3D B‐Te‐based device that shows good OTS characteristics. In addition, the OTS device successfully suppresses the leakage current in half‐selected cells when it is integrated with a resistive random access memory (ReRAM) device. [ABSTRACT FROM AUTHOR]

NbO 2 has the potential for a variety of electronic applications due to its electrically induced insulator-to-metal transition (IMT) characteristic. In this study, we find that the IMT behavior of NbO 2 follows the field-induced nucleation by investigating the delay time dependency at various voltages and temperatures. Based on the investigation, we reveal that the origin of leakage current in NbO x is partly due to insufficient Schottky barrier height originating from interface defects between the electrodes and NbO x layer. The leakage current problem can be addressed by inserting thin NiO y barrier layers. The NiO y inserted NbO x device is drift-free and exhibits high I on /I off ratio (>5400), fast switching speed (<2 ns), and high operating temperature (>453 K) characteristics which are highly suitable to selector application for x-point memory arrays. We show that NbO x device with NiO x interlayers in series with resistive random access memory (ReRAM) device demonstrates improved readout margin (>2 9 word lines) suitable for x-point memory array application.