Relaxation oscillations in NbO2 thin film switching devices

Quantum materials for brain sciences and artificial intelligence

“…[20][21][22] In fact, relaxation oscillations in NbO 2 were observed more than 35 years ago, indicating long-standing interest in the unique electronic behavior of phase switches. 23 Such a device can integrate charge and fire at a threshold voltage that directly mimics a biological neuron. By careful choice of the correlated insulator and optimization of the geometry and ground-state conductivity with defects, it is possible to tune the critical voltages needed for firing.…”

Threshold switching and electrical self-oscillation in niobium oxide films

“…Although there are some early reports on NbO 2 selfoscillation, 19,20 Lalevic and Shoga first reported stable and reproducible oscillations with frequency up to $600 kHz in single crystal NbO 2 and polycrystalline NbO x films in 1981. 21 Recently, several reports have highlighted the nonlinear current-voltage (I À V) characteristics of electrically switched NbO x thin films [22][23][24][25] and the occurrence of MHz periodic oscillation signals maintained across two-terminal devices. 7,26,27 Our previous study demonstrated the electrical self-oscillation with a frequency of tens of MHz in a Ti/NbO x NDR device with low operation voltages, large frequency control range, and long endurance.…”

Electronic structure and transport measurements of amorphous transition-metal oxides: observation of Fermi glass behavior

“…[17] has intermediate phases with lower oxidation states (typically MeO and MeO 2 ) than the terminal oxide. The Nb-O system was chosen to represent this class because each of its phases exhibits a unique conduction behavior: pure Nb is a superconductor, NbO is metallic [18], NbO 2 exhibits a metal-insulator transition and a related negative differential resistance (NDR) [19][20][21], and Nb 2 O 5 is a highly insulating dielectric. The last class of TMO's, such as W-O, Ti-O, V-O, etc.…”