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.

Area and Thickness Scaling of NbOₓ-Based Threshold Switches for Oscillation Neurons

“…2(b), Vth was proportional to the thickness, and the Vth started to steadily increase as the device area decreased. The number of oxygen vacancies corresponding to the traps was reduced with area scaling, reducing the probability of oxygen vacancies to induce nucleation [14]. Thus, larger Vth was needed to attract the vacancies farther away from the nucleus in NbOx for the phase transition.…”

Effect of Stochastic Resonance on Classification Accuracy of Neural Networks Utilizing Inherent Stochasticity in Threshold Voltage of Ovonic Threshold Switching Device

“…The switching of OTS is associated with traps in amorphous chalcogenide materials [18][19]. Thus, the OTS devices have inherent stochastic characteristics owing to RTN [20], and random formation of percolation clusters [19]. Furthermore, 1/f fluctuation in the subthreshold regime induces stochastic threshold switching [21].…”

Effect of the Oxygen Composition Control of HfOx Films on Threshold and Memory Switching Characteristics for Hybrid Memory Applications

“…[ 1,2 ] To realize a high‐density cross‐point array with a small cell size, an outstanding selector device is required to suppress the sneak path current with neighboring cells. [ 3–11 ] Among the several types of selector devices, ovonic threshold switches, [ 4,12,13 ] insulator‐to‐metal transition selectors, [ 14,15 ] and programmable metallization cell‐based threshold switching (TS) devices are promising candidates for selector devices in high‐density cross‐point arrays. [ 16–26 ]…”