Electrodes as the protagonists in composite barrier Ferroelectric Tunnel Junctions

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 (delta/epsilon). The Tunneling electro resistance ratio (TER) becomes significant for bias potential V > |P| (delta(1)/ epsilon(1) +t(d)/ epsilon(d) + delta(2) /epsilon(2))wherein the screening charge density sigma(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/20 angstrom STO/24 angstrom BTO/SRO system with an active device length of 7.6 nmis found to have a current density of 3.38x10(4) A cm(-2) and 0.22 A cm(-2) in the ON and OFF state and an absolute TER of around 1.52x10(5)% at the bias of 0.77 Vconform to the necessary conditions of efficient application in memory devices.