Effect of oxygen vacancy and Si doping on the electrical properties of Ta2O5 in memristor characteristics

Abstract The resistive switching behavior in Ta 2 O 5 based memristors is largely controlled by the formation and annihilation of conductive filaments (CFs) that are generated by the migration of oxygen vacancies (OVs). To gain a fundamental insight on the switching characteristics, we have systematically investigated the electrical transport properties of two different Ta 2 O 5 polymorphs ( $$\epsilon$$ ϵ -Ta 2 O 5 and λ-Ta 2 O 5 ), using density functional theory calculations, and associated vacancy induced electrical conductivity using Boltzmann transport theory. The projected band structure and DOS in a few types of OVs, (two-fold (O 2f V), three-fold (O 3f V), interlayer (O IL V), and distorted octahedral coordinated vacancies (O ε V)) reveal that the presence of O IL V would cause Ta 2 O 5 to transition from a semiconductor to a metal, leading to improved electrical conductivity, whereas the other OV types only create localized mid-gap defect states within the bandgap. On studying the combined effect of OVs and Si-doping, a reduction of the formation energy and creation of defect states near the conduction band edge, is observed in Si-doped Ta 2 O 5 , and lower energy is found for the OVs near Si atoms, which would be advantageous to the uniformity of CFs produced by OVs. These findings can serve as guidance for further experimental work aimed at enhancing the uniformity and switching properties of resistance switching for Ta 2 O 5 -based memristors.