Effect of Silicon Doping in B–Te (B<sub>4</sub>Te₆) Binary Ovonic Threshold Switch System
Sanghyun Ban, Sangmin Lee, Jangseop Lee, Hyunsang Hwang
Abstract
In this study, we comprehensively investigated the effect of Si doping on a boron-tellurium (B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> Te <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> ) based binary ovonic threshold switch (OTS). Through Si doping, we achieved an OTS that is more suitable for mass-produced large arrays featuring low off-leakage current ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{I}_{\mathrm {off}}$ </tex-math></inline-formula> ) characteristics improved by more than one order, low drift characteristics improved by ~33%, and a higher threshold voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{V}_{\mathrm {th}}$ </tex-math></inline-formula> ) at the same thickness. Raman spectroscopy was used to determine the mechanism governing this significant electrical change caused by Si doping. The results revealed that the improvement in the drift characteristics may be related to the reduction of thermodynamically unstable homopolar Te–Te bonds and the formation of additional stable heteropolar bonds. Furthermore, investigations of the optical bandgap ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{E}_{{\mathrm {g}}}^{{\mathrm {opt}}}$ </tex-math></inline-formula> ) based on the ultraviolet-visible absorbance and sub-threshold <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{I}-\text{V}$ </tex-math></inline-formula> analyses indicated that the increase in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{V}_{\mathrm {th}}$ </tex-math></inline-formula> and improvement in the off-leakage characteristics caused by Si doping were associated with the increased bandgap. In addition, X-ray diffraction (XRD) analysis indicated that excellent thermal stability characteristics were maintained up to 450 °C even after Si doping.