Controlled Sign Reversal of Electroresistance in Oxide Tunnel Junctions by Electrochemical-Ferroelectric Coupling

Switchable Optically Active Schottky Barrier in La0.7Sr0.3MnO3/BaTiO3/ITO Ferroelectric Tunnel Junction

“…[35], and in agreement with previous works from other groups. [20,31,35] Schottky barriers in FE materials are known to increase their very attractive photovoltaic effect. [12][13][14][15][16][36][37][38] FE photovoltaic devices are characterized by a diode-like electric transport with a photocurrent in the opposite direction to the FE polarization.…”

“…[ 35 ] , and in agreement with previous works from other groups. [ 20,31,35 ]…”

“…[ 35 ] ). [ 35 ] Tunnel junctions are fabricated defining eight contact areas of 9 × 18 µm 2 with optical lithography and depositing 150 ± 10 nm ITO as a top electrode through a shadow mask, at room temperature in a DC magnetron sputtering. Electric transport in dark was characterized with a Keithley 2450 source measure unit grounding the top ITO electrode (inset of Figure a).…”

“…Interestingly, it is reported as the fingerprint of a RS ruled by a Schottky barrier formation due to the migration of oxygen vacancies to the LSMO/BTO interface. [ 26,31,33–35,42 ] Therefore, the “chirality” of the I – V and the RS loops of Figure 1a,b indicates the creation and suppression of a Schottky barrier as the oxygen vacancies accumulate ( R High ) or are depleted ( R Low ) at the LSMO/BTO interface, following the external field. Taking into account the LSMO work function W LSMO = 4.8 eV and the BTO electron affinity χ BTO = 3.9 eV, the Schottky–Mott rule estimates a Schottky barrier of ϕ 0 B = 0.9 eV at the LSMO/BTO interface, and a lower ϕ 0 B2 = 0.6 eV at the BTO/ITO ( W ITO = 4.5 eV).…”

“…In this work a series of FTJ are studied, based on epitaxial bilayers of 20 nm La 0.7 Sr 0.3 MnO 3 and 5 nm BaTiO 3 , which were grown on STO substrates using a high pressure RF sputtering in a pure oxygen atmosphere. [8,[33][34][35]41] High resolution electron microscopy STEM imaging and elemental maps, and atomic force microscopy show structurally and chemically atomically sharp interfaces, and one-unit cell terraces in the surface of the BTO layer. [33,34] Piezoelectric force microscopy using both amplitude and phase contrast shows hysteresis loops and FE domain reversal with a few tip volts (see Figure 1 of ref.…”