Suppressing the current leakage and voltage drift in indium-modified electrical switching devices

Abstract

Ovonic threshold switching (OTS) devices are essential selectors for high-density memory arrays, but their operational reliability is often limited by the threshold-voltage (V_th) drift arising from structural relaxation in amorphous chalcogenides. Although widely reported, the atomic mechanism behind the V_th drift remains insufficiently understood, limiting the rational design of highly stable OTS devices. Here, we investigate the atomic origin of the V_th drift in In–Te OTS devices (InTe₄, InTe₃, and In₃Te₇) and demonstrate that reducing homopolar Te–Te bonding effectively suppresses the structural relaxation and V_th drift. A higher In content lowers the leakage current, increases V_th, and significantly suppresses the V_th drift. The optimized In₃Te₇ devices achieve an on/off ratio of ∼10⁵, a low V_th drift coefficient of 26 mV dec⁻¹ and endurance exceeding 10⁸ cycles. Ab initio molecular dynamics (AIMD) simulations further demonstrate that a portion of Te–Te homopolar bonds gradually disappear during structural relaxation and that the increased In content suppresses both homopolar bonding and the formation of over-coordinated Te atoms, which are responsible for defect states inside the bandgap. This study clarifies the origin of V_th drift and provides a practical material-engineering strategy for developing reliable OTS selectors for future 3D memory technologies.