Probing hot electron transport across an epitaxial Schottky interface of SrRuO3/Nb:SrTiO3

Abstract

SrRuO 3 (SRO), a conducting transition metal oxide, is commonly used for engineering domains in BiFeO 3. New oxide devices can be envisioned by integrating SRO with an oxide semiconductor as Nb doped SrTiO 3 (Nb:STO). Using a three-terminal device configuration, we study vertical transport in a SRO/Nb:STO device at the nanoscale and find local differences in transport, that originate due to the high selectivity of SRO growth on the underlying surface terminations in Nb:STO. This causes a change in the interface energy band characteristics and is explained by the differences in the spatial distribution of the interface-dipoles at the local Schottky interface.Complex oxide heterointerfaces are of immense interest in oxide electronics and has led to the emergence of new physical phenomena that arises due to competing energy scales involved in the interplay between the structural, charge, spin and orbital degrees of freedom. [1][2][3][4] Moreover, the possibility to control and manipulate carrier spin polarization at heterointerfaces between transition metal oxides [5][6] and the demonstration of novel functionalities at the domain walls in multiferroic materials [7][8] have opened new frontiers in oxide spintronics. A promising material among the complex oxides is SrRuO 3, which apart from being metallic is also ferromagnetic (below 160 K) [9] and thus can find use both in oxide electronics and spintronics. In spite of this, not much is known about electron transport across a functional interface of SRO particularly with an oxide semiconductor as Nb doped SrTiO 3 , although the physical properties of SRO films have been extensively studied. It has been reported that the surface terminating plane of the underlying substrate can influence the initial growth of the deposited SRO films and has been proposed to be an interesting approach to fabricate ordered oxide nanostructures [10][11] . Trenches that are created in thin films of SRO are associated with a local surface termination of SrO at the STO substrate, where the initial growth of SRO is unfavorable. Regions in between the trenches are areas of

Interface control of electronic transport across the magnetic phase transition in SrRuO3/SrTiO3 heterointerface

“…2a ) 23 . It matches well with our previously extracted values for such an interface 24 . As the thickness of SrRuO 3 films is increased, a decrease in transmission is observed.…”

Effect of surface structure on workfunction and Schottky-barrier height in SrRuO3/SrTiO3 (001) heterojunctions

“…26 The SrRuO 3 /SrTiO 3 (001) heterostructure is a prototypical system to study SBH at the oxide metal/dielectric interface. [27][28][29] Here the SrRuO 3 (SRO) and SrTiO 3 (STO) are the metallic and insulating oxides crystallizing in perovskite structure. Recently, reversible resistance switching has been demonstrated at the Schottky interface in SrRuO 3 /Nb:SrTiO 3 structure, 29 which has potential applications in resistance switcing random access memories.…”

Reversible modulation of electric transport properties by oxygen absorption and releasing on Nb:SrTiO3 surface

“…or half-integral multiple of 0.4 nm, which is just the lattice constant of NSTO. 22,23 This result indicates that there are two types of terrace planes (A and B) on sample surface; 11,26,27 the step height between the A-A or B-B planes is an integral multiple of one unit cell, whereas it is half-integral multiple of one unit cell between the A and B planes. These are general features in the AFM images collected from different locations of the sample, confirming that the as-prepared NSTO sample indeed possesses two types of terminated layers.…”

“…Issues concerned include the chemical balance of dopants and defects as well as the properties of surface barrier. [8][9][10][11][12] With the variation of Nb content, the conductivity of NSTO can be semiconductive, metallic, or even superconductive. However, the metal/ NSTO contact is usually non-ohmic, exhibiting a rectifying behavior.…”