Unravelling the atomic mechanisms of tetrahedral doping in chalcogenide glass for electrical switching materials

Abstract

The ovonic threshold switching (OTS) selector is crucial for the development of high-density memory devices based on three-dimensional semiconductor integration technology, as it could suppress leakage current. However, the performance of OTS materials based on chalcogenide glass is not yet satisfactory, hindering the progress of industrial advancement. Si doping, by introducing tetrahedral sp³ bonding into materials, is a key method to improve the thermal stability of chalcogenide glass, but the specific mechanism of such a dopant is not very clear. In this study, we investigated the effect of Si doping on the local structure, bonding nature, and electronic properties of amorphous GeSe (a-GeSiSe), to gain a better understanding of the doping effect. Our results suggest that Si atoms form tetrahedral motifs with stronger Si–Ge and Si–Se bonds, thus slowing down the atomic mobility to increase the activation energy of crystallization. Moreover, the resulting narrowed band gap of a-GeSiSe is advantageous in decreasing the threshold voltage (V_th). In addition, Si doping leads to stable mid-gap states and thus effectively suppresses the V_th drift. Our study elucidates the important role of Si doping in OTS materials and facilitates the development of 3D phase-change memory.