Effects of N-doped GeSbTe buffer layer on switching characteristics of Cu/Al₂O₃-based CBRAM

In this paper, we investigated the effects of inserting an N-doped GeSbTe buffer layer on a Cu/Al₂O₃-based conducting-bridge random-access memory (CBRAM). The N-doped GeSbTe buffer layer induced a limited Cu ion injection during the set process due to Cu-Te bonding and N-doping inthe buffer layer. In addition, joule heating confinement resulting from the low-thermal-conductivity buffer layer led to a low-residual conductive filament after the reset process. As a result, the on/off ratio of the Cu/Al₂O₃-based device increased from 10² to 10⁵. Furthermore, the variability of the switching parameters such as high-resistance state and set/reset voltages distributions was significantly mitigated. The N-doping effects were confirmed by comparing the GeSbTe and the N-doped GeSbTe buffer-layer-inserted devices. The N-doped GeSbTe-inserted CBRAM exhibited an on/off ratio of > 10⁵ up to 300 DC cycles without any noticeable data-state degradation.