Understanding of forming and switching mechanism using trap distribution model for ovonic threshold switch device

Abstract

In this study, we investigate the electrical characteristics of a W/Si–Te–As–Ge/W ovonic threshold switch (OTS) under various conditions to reveal the origin of its forming and its effect on the subsequent threshold switching. Our results indicate that the forming of the OTS is a process of generating a metastable filamentary conductive path with a statistical nature, which leaves behind the lowest energy level of the activated trap, thereby significantly affecting the subsequent conduction as well as the dynamics of the threshold switching in the OTS. In addition, we apply a hot forming technique to control the distribution and energy level of the residual traps. By forming at elevated temperatures, the overshoot damage due to abrupt switching can be reduced. As a result, the trap distance and activation energy can be increased, the off current decreases from 54 to 7 nA (1/2 Vth read), and the threshold voltage increases from 1.5 to 1.7 V.