Electrodes as the protagonists in composite barrier Ferroelectric Tunnel Junctions

Abstract

Abstract The role of electrodes in composite barrier Ferroelectric Tunnel Junctions (FTJs) is investigated for the systems (//Pt/STO/BTO/SRO, //Pt/STO/BTO/Pt, //SRO/STO/BTO/SRO and //SRO/STO/BTO/Pt). The tunneling current is controlled by the potential drop in the accumulation and depletion region in the electrodes which depends on the ratio of their screening length to permittivity (δ/ ϵ ). The Tunneling electro resistance ratio (TER) becomes significant for bias potential V > P δ 1 ϵ 1 + t d ϵ d + δ 2 ϵ 2 wherein the screening charge density σ s remains negative causing the pull-down of the barrier towards the Fermi level and an increase in the tunneling current. Among the studied systems //Pt/20Å STO/24Ǻ BTO/SRO system with an active device length of 7.6 nm is found to have a current density of 3.38 × 104 A cm−2 and 0.22 A cm−2 in the ON and OFF state and an absolute TER of around 1.52 × 105% at the bias of 0.77 V conform to the necessary conditions of efficient application in memory devices.