  The recent surge of interest in brain-inspired computing and power-efficient
electronics has dramatically bolstered development of computation and
communication using neuron-like spiking signals. Devices that can produce rapid
and energy-efficient spiking could significantly advance these applications.
Here we demonstrate DC-current or voltage-driven periodic spiking with sub-20
ns pulse widths from a single device composed of a thin VO2 film with a
metallic carbon nanotube as a nanoscale heater. Compared with VO2-only devices,
adding the nanotube heater dramatically decreases the transient duration and
pulse energy, and increases the spiking frequency, by up to three orders of
magnitude. This is caused by heating and cooling of the VO2 across its
insulator-metal transition being localized to a nanoscale conduction channel in
an otherwise bulk medium. This result provides an important component of
energy-efficient neuromorphic computing systems, and a lithography-free
technique for power-scaling of electronic devices that operate via bulk
mechanisms.

Applied Physics;Mesoscale and Nanoscale Physics