Carbon electrode for Ge-Se-Sb based OTS selector for ultra low leakage current and outstanding endurance

Abstract : In this paper we study the reliability of a N-doped Ge-Se-Sb based Ovonic Threshold Switching (OTS) Selector targeting high density Crossbar memory arrays. Through TEM analysis, we investigate the interaction between the TiN electrode and the chalcogenide layer, highlighting that the Ti diffusion appears to be the main mechanism responsible for the degradation of the device performances. In order to prevent this phenomenon, we engineered a thin carbon layer inserted in between the TiN electrode and the OTS material. Selector device performances are then considerably improved, achieving an ultra-low leakage current of 10 pA and an endurance of 10$^9$ cycles. These results are, at our knowledge, among the best reported so far in the literature for a back-end-of-line OTS selector technology.