Growth and characterization of niobium oxide memristors

Niobium oxide memristors have gained a surge of recent attention owing to their applicability as selectors in resistive random access memory, elements of the neuristor and components of a neuromorphic computer operated at the... [ view full abstract ]

Niobium oxide memristors have gained a surge of recent attention owing to their applicability as selectors in resistive random access memory, elements of the neuristor and components of a neuromorphic computer operated at the edge of chaos. The underlying principle of these applications is the local activity exhibited by NbOx upon an energy stimulus, often seen as a region of negative differential resistance (NDR) in a plot of current and voltage. Here we experimented with various growth conditions for reactively sputtered NbOx films, characterized in relative variations in composition and structure using x-ray spectroscopic techniques. We built devices with a variety of film stacks, especially with the inclusion of a reactive electrode material, TiN. We correlated these variations with their electrical characteristics and identified growth parameters and the resulting film’s compositional and structural characteristics that allowed the devices to exhibit NDR. We found that the presence of a TiN electrode was necessary for NDR. There have been several recent efforts to model the origins of the NDR behavior based on multiple conduction mechanisms. We show that our data can be modeled using a Poole-Frenkel-like emission leading to a superlinear temperature dependence of conductivity, confirming the generality of recently proposed models.