Inhomogeneous barrier heights at dipole-controlled SrRuO3/Nb:SrTiO3 Schottky junctions

It has recently been shown that the Schottky barrier height (SBH) formed at metal-semiconductor perovskite oxide heterojunctions can be dramatically tuned by the insertion of atomic-scale dipole layers at the interface. However, in idealized form, this would only allow for specific values of the SBH...

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Bibliographic Details
Published in:Applied physics letters 2018-11, Vol.113 (22)
Main Authors: Yajima, T., Minohara, M., Bell, C., Hwang, H. Y., Hikita, Y.
Format: Article
Language:English
Subjects:
Applied physics
Depletion
Dipoles
electronic bandstructure
Heterojunctions
heterostructures
I-V characteristics
MATERIALS SCIENCE
Ohmic contacts
Perovskites
Schottky barriers
semiconductors
Strontium titanates
thermionic emission
Thickness
thin films
transition metal oxides
Unit cell
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Summary:It has recently been shown that the Schottky barrier height (SBH) formed at metal-semiconductor perovskite oxide heterojunctions can be dramatically tuned by the insertion of atomic-scale dipole layers at the interface. However, in idealized form, this would only allow for specific values of the SBH, discretized by the dipole layer thickness. Here, we examine the effect of fractional unit cell LaAlO3 dipoles inserted between SrRuO3 and Nb:SrTiO3 in (001) Schottky junctions, as a function of their in-plane lateral distribution. When the LaAlO3 dipoles are finely dispersed, we observe uniformly rectifying junctions, with SBHs reflecting the fractional LaAlO3 coverage. For larger length-scale distributions, the junction characteristics reflect the inhomogeneous combination of regions with and without the interface dipole. The characteristic length scale dividing the two regimes corresponds to the semiconductor depletion width scaled by the dipole potential, determining the effective scale for which the SBH can be continuously tuned.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.5052712