First principle investigation of polaronic resistive switching behavior in titania based memristors with different charge states

Abstract

Resistive random-access memory (RRAM) also referred as memristors are considered a critical component of nano-electronics. In this first principle study we presented a polaron related model. We revealed polaron; a conducting species in mediating resistive switching (RS) mechanism in anatase polymorph of TiO2 bulk based memristors. We examined polaron formation after substitution of silver (Ag), copper (Cu) and nickel (Ni) in place of titanium (Ti) atom. Influence of charge addition (q- and q-), charge removal (q+ and q++) and neutral (q0) states of doped system on polaron based conducting filaments are also explored. Various values of formation energy indicated the influence of charged state variation on conductivity of the three doped systems. Findings of iso-surface charge density plots indicated polaron formed around the substitutional dopants characterized by localized states in band gap region of density of states (DOS). Presence of localized state in band gap region that confirm the achievement of RS mechanism in these doped systems. Our results predicted Cu as a best substitutional dopant for polaron as a conducting species for RS mechanism. Integrated charge density plots also confirmed these results. Interstitially doped Ag, Cu and Ni doped TiO2 systems with different charged states showed the conducting filaments formed for RS mechanism with no polaron formation. This study suggests that charged states tuned polaron in substitutional doped TiO2 will allow to construct conducting pathway for polaronic RS mechanism in nanoelectronics beyond RRAM.