Studies on switching mechanisms in Pd-nanodot embedded Nb2O5 memristors using scanning tunneling microscopy

Current imaging tunneling spectrum obtained from scanning tunneling microscopy has been used to probe the formation and/or rupture of conductive filaments responsible for bipolar switching in Pd nano-dots embedded Nb2O5 memristors. Filamentary conduction mechanism has been confirmed by scanning tunneling microscopy study using a Pt–Ir tip that enabled performing electroforming and reset operations at the nanoscale. The back and forth transition between the fully oxidized and metallic sub-oxide states of niobium under applied bias, as observed from X-ray photoelectron spectroscopy, is believed to be the source of bipolar switching in Nb2O5 memristors. The incorporation of Pd nanodots in Nb2O5 matrix plays a critical role by acting as an oxygen ion reservoir and/or by polarizing a large volume of oxygen vacancies. The formation and/or rupture of the conducting filaments through trapping–detrapping phenomena are found to boost the memristive switching performance.

► STM technique has been applied to study the resistance switching.
► Use of Pd nanodots enhances the switching in Nb2O5 memristors.
► Origin of switching is found to be due to multiple oxide states of Nb.