Structural and electrical characterization of ultra-thin SrTiO₃tunnel barriers grown over YBa₂Cu₃O₇electrodes for the development of highT_cJosephson junctions

Abstract

The transport properties of ultra-thin SrTiO(3) (STO) layers grown over YBa(2)Cu(3)O(7) electrodes were studied by conductive atomic force microscopy at the nano-scale. A very good control of the barrier thickness was achieved during the deposition process. A phenomenological approach was used to obtain critical parameters regarding the structural and electrical properties of the system. The STO layers present an energy barrier of 0.9 eV and an attenuation length of 0.23 nm, indicating very good insulating properties for the development of high-quality Josephson junctions.

High transition temperature superconductor/insulator bilayers for the development of ultra-fast electronics

“…Moreover, the more insulating the barrier (k smaller) is the higher a 0 seems to be. 15 This is coherent with our results. The reduction of the tunnelling current with increasing barrier thickness for GBCO/STO bilayers is smaller than the observed for YBCO/STO bilayers, and in the latter, a 0 is around 3.5, larger than the value obtained for this system ($2.7).…”

Electrical and magnetic properties of FM/MgO/FM (FM = Co90Fe10, Fe20Ni80) heterostructures

“…Due to a lower value of effective roughness and a similar crystalline structure with the electrodes, MgO substrates would favor the crystallinity of the layers improving the conductivity through the insulating barrier. Previous studies on the influence of the substrate roughness on the transport properties of tunnel barriers have also shown an influence on the attenuation length and energy barrier for systems grown on different substrates [11,28]. Calculated value of the current density for the trilayer system grown on MgO substrate was 1.29 nA μm −2 at 1.5 V, One order of magnitude higher than the samples grown on Si(1 0 0).…”

“…the attenuation length, the density of pinholes, the energy barrier, etc). Some effort to address this issue has been done in previous works [11,12]. However, topographical and magnetic features of the electrodes also plays an important role on the electronic tunneling of the charge carriers through the barrier, therefore a good selection of the electrodes should also be made.…”

Understanding Current Instabilities in Conductive Atomic Force Microscopy

“…It is worth noting that, as we are collecting only spectroscopic measurements and negligible lateral frictions apply, the use of a high contact force should not provoke premature CAFM tip degradation. Despite being very useful for the characterization of several nanomaterials, current/resistance maps [22,23,24] are not used in this study, because that exposes the tip to high lateral and nearly uncontrollable frictions.…”