Generation of electrical self-oscillations in two-terminal switching devices based on the insulator-to-metal phase transition of VO₂ thin films

Abstract

We present the non-linear electrical properties of simple two-terminal switching devices based on vanadium dioxide (VO 2 ) thin films. The current–voltage characteristics of such devices present negative differential resistance (NDR) regions allowing generating electrical self-oscillations across the investigated devices, with frequencies ranging from several kHz up to 1 MHz. We investigate and compare the factors determining the onset of oscillatory phenomenon in both voltage- and current-activated oscillations and explain its origin. For both activation modes, we will correlate the properties of electrical oscillations (amplitude and frequency) with the amplitude of the continuous excitation signal, the physical geometry of the devices or ambient temperature. We conclude by mentioning several possible applications for the oscillation generation in the radiofrequency (RF)/microwave domains (inverters, integrated a.c. signal generators, pressure and temperature sensors, etc.).