Effect of nitrogen doping on characteristics of SiTe Ovonic threshold switch for selectors

Abstract

In this study, the effect of nitrogen doping on silicon telluride (SiTe) chalcogenide materials has been investigated to enhance the performance of the Ovonic threshold switch (OTS) selector devices especially on the off-current density to reduce sneak current. The nitrogen doped SiTe (N–SiTe) device demonstrates significant improvement in selector performance including low off-current (18 nA) and low off-current density (3.4 × 10−4 kA/cm2) resulting in high selectivity (5.5 × 104), low power operation at threshold voltage of 0.96 V, enhanced voltage window (0.24 V), fast switching with slope of < 2.97 mV/dec and potentially fast pulse response/switching speed. Besides, analyses by Raman and X–ray photoelectron spectroscopies indicate that the nitrogen doping changes predominant orbital and bonding configuration and decreases Te lone pairs that act as traps, thus suppressing subthreshold conduction. Increased optical bandgap by nitrogen doping also results in reduced leakage current as well as higher threshold voltage. First-principles calculations reveal that localized electrons with high density near nitrogen are responsible for reduced subthreshold conduction of the chalcogenide. Our results provide new guidance in material selection by demonstrating the effect of nitrogen doping to improve OTS selector performance on an arsenic-free binary chalcogenide.