Material and Structural Engineering of Ovonic Threshold Switch for Highly Reliable Performance

As a selection device for highly integrated crossbar-type data storage, the chalcogenide-based ovonic threshold switch (OTS) shows high selectivity, fast switching speed, and bi-directional operation ability for stacking with versatile memory devices. These promising performance features of OTS are based on electronic resistance switching through the amorphous chalcogenide active layer. However, there is a need to improve the thermal stability of the chalcogenide material, which is essential for maintaining the amorphous structure, and the minimization of the operation voltage shift phenomenon, which is essential for achieving sufficient endurance performance. In this study, the active layer of Se-doped (at 5%) GeTe (SGT) is investigated as a selection device with the potential for high thermal stability (<400 degrees C) and extreme endurance performance (>10(12)). The Se introduced into the GeTe (GT) layer compensates for the Te vacancy in the GT layer, making the SGT layer resistant to crystallization in high-thermal-budget circumstances. To achieve extremely high endurance performance, a device structural reconfiguration is proposed that minimizes the operation voltage shift by restricting the surge current in its initial resistance switching stage. The results of analyses of the materials and electrical characteristics of the OTS demonstrate its enhanced performance.