Excellent Selector Characteristics of Nanoscale VO₂ for High-Density Bipolar ReRAM Applications

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">(VO₂)</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">$>$</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">$<$</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">(>10⁶\ A/cm²)</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">VO₂</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">(< 5 × 10⁴\ nm²)</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">VO₂</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">VO₂</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">VO₂ </tex></formula> selection device shows good potential for cross-point bipolar resistive memory applications.