High-endurance megahertz electrical self-oscillation in Ti/NbOx bilayer structures

Abstract

Electrical self-oscillation is reported for a Ti/NbOx negative differential resistance device incorporated in a simple electric circuit configuration. Measurements confirm stable operation of the oscillator at source voltages as low as 1.06 V, and demonstrate frequency control in the range from 2.5 to 20.5 MHz for voltage changes as small as ∼1 V. Device operation is reported for >6.5 × 1010 cycles, during which the operating frequency and peak-to-peak device current decreased by ∼25%. The low operating voltage, large frequency range, and high endurance of these devices makes them particularly interesting for applications such as neuromorphic computing.

Compact oscillation neuron exploiting metal-insulator-transition for neuromorphic computing

“…It has been reported that the oscillation frequency of MIT devices with the circuit configuration in Fig. 2(b) can be up to several 10's to 100's MHz [20,22]. It is highly probable that the reported frequency is limited by the parasitic RC delay in the off-chip electrical measurement setup.…”

Fast Spiking of a Mott VO2–Carbon Nanotube Composite Device

“…16,17 Relaxation oscillators that are constructed with NbO2 or VO2 typically use a DC-current or voltage driven Pearson-Anson-like circuit that includes a capacitor in parallel with the NDR element, and a suitable series resistor. 15,[18][19][20][21][22] However, generation of fast DC-voltage-driven periodic spiking will require aggressive scaling to minimize both the electrical and thermal time constants of these oscillators, 11,23 for instance, by careful electron-beam lithography, which may not be practical for largescale electronics.…”

The role of defects in the electrical properties of NbO2 thin film vertical devices

“…[14][15][16] Within the region of negative differential resistance, the current remains unstable and self-sustained current oscillations can be generated. 12,16 The high MIT temperature of NbO 2 favors fast switching and high frequency current oscillations because the device can cool quickly below T MIT .…”

“…9 Reversible threshold switching in current has been reported mostly using amorphous NbO 2 films, where the current turns off immediately after lowering the input voltage (V in ) below the threshold voltage (V th ). 3,[10][11][12][13] Current-voltage (IV ) characteristics usually exhibit current-controlled (s-type) negative differential resistance (dV /dI < 0) while switching from a low current semiconducting to a high current metallic state. [14][15][16] Within the region of negative differential resistance, the current remains unstable and self-sustained current oscillations can be generated.…”