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Effect of Cationic Interface Defects on Band Alignment and Contact Resistance in Metal/Oxide Heterojunctions
Author(s) -
Andrä Michael,
Funck Carsten,
Raab Nicolas,
Rose MarcAndré,
Vorokhta Mykhailo,
Dvorˇák Filip,
Šmíd Brˇetislav,
Matolín Vladimír,
Mueller David N.,
Dittmann Regina,
Waser Rainer,
Menzel Stephan,
Gunkel Felix
Publication year - 2020
Publication title -
advanced electronic materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.25
H-Index - 56
ISSN - 2199-160X
DOI - 10.1002/aelm.201900808
Subject(s) - heterojunction , materials science , schottky barrier , ionic bonding , oxide , contact resistance , annealing (glass) , nanotechnology , optoelectronics , chemical physics , layer (electronics) , composite material , ion , chemistry , diode , organic chemistry , metallurgy
Abstract Heterojunctions between high‐work‐function metals and metal oxides typically lead to Schottky‐type transport barriers resulting from charge transfer between the neighboring materials. These yield versatile electronic functionality exploited for current rectification, memristive behavior, or photocatalysis. Height, width, and shape of the interfacial transport barrier are strongly affected by charge screening via ionic defects, which are often extremely difficult to probe. The ionic nature of a variable contact resistance in heterojunctions between Nb‐doped SrTiO 3 (Nb:SrTiO 3 ) and platinum is explored. A control of cationic vacancy defects at the interface is achieved by different annealing procedures in oxidizing and reducing conditions before establishing Pt/Nb:SrTiO 3 heterojunctions. Detailed analysis of electronic transport across the heterojunctions reveal significantly varied transport barriers resulting from the cationic defect structure at the interface. These findings are supported by conductive‐tip atomic force microscopy and in situ photoemission spectroscopy showing diminished conductivity of the Nb:SrTiO 3 surface and the formation of an insulating surface skin layer after oxygenation. At high doping level, oxygen stoichiometry cannot explain the observed behavior. The increased transport barrier height is therefore linked to strontium vacancy defects. The tailored cation disorder yields access to the ionic control of electronic transport in functional oxide heterojunctions.