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

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