Subthreshold Bias-Induced Threshold Voltage Shift of the Ovonic Threshold Switch

Abstract

In this study, we report on the subthreshold bias-induced threshold voltage shift (SITS) phenomenon of an ovonic threshold switch (OTS) that can occur during array inhibit operation in a cross-point memory. We found that the threshold voltage ( V-th) of the OTS increases after applying a bias to the subthreshold region of the OTS. In particular, the closer the subthreshold bias is to the V(th )of the OTS, and the longer the width of the bias pulse, the greater the SITS effect. As this SITS phenomenon can occur at half-biased cells during the inhibit operations of read and write, it should be considered as a factor affecting V-th instability. Based on the changes in drift characteristics after subthreshold biasing and the analysis of off-leakage fitting parameters, it can be concluded that the SITS phenomenon is likely to be associated with the acceleration of the defect annihilation in the OTS film.