Excellent Selector Characteristics of Nanoscale $ \hbox{VO}_{2}$ for High-Density Bipolar ReRAM Applications

Abstract

We herein present a nanoscale vanadium oxide <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$(\hbox{VO}_{2})$</tex> </formula> device with excellent selector characteristics such as a high on/off ratio ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$&gt;$</tex></formula> 50), fast switching speed ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$&lt;$</tex></formula> 20 ns), and high current density <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$(&gt;\hbox{10}^{6}\ \hbox{A/cm}^{2})$</tex></formula> . Owing to extrinsic defects, a large-area device with a 20-nm-thick <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{VO}_{2}$</tex></formula> layer underwent an electrical short. In contrast, after scaling the device active area <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$(&lt; \hbox{5} \times \hbox{10}^{4}\ \hbox{nm}^{2})$</tex></formula> , excellent switching uniformity was obtained. This can be explained by the reduced defects and the metal–insulator transition of the whole nanoscale <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{VO}_{2}$</tex></formula> . By integrating a bipolar resistive random access memory device with the <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{VO}_{2}$</tex></formula> selection device, a significantly improved readout margin was obtained. The <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{VO}_{2}$ </tex></formula> selection device shows good potential for cross-point bipolar resistive memory applications.