A Microdot Multilayer Oxide Device: Let Us Tune the Strain-Ionic Transport Interaction

Abstract

In this paper, we present a strategy to use interfacial strain in multilayer heterostructures to tune their resistive response and ionic transport as active component in an oxide-based multilayer microdot device on chip. For this, fabrication of strained multilayer microdot devices with sideways attached electrodes is reported with the material system Gd0.1Ce0.9O(2-δ)/Er2O3. The fast ionic conducting Gd0.1Ce0.9O(2-δ) single layers are altered in lattice strain by the electrically insulating erbia phases of a microdot. The strain activated volume of the Gd0.1Ce0.9O(2-δ) is investigated by changing the number of individual layers from 1 to 60 while keeping the microdot at a constant thickness; i.e., the proportion of strained volume was systematically varied. Electrical measurements showed that the activation energy of the devices could be altered by Δ0.31 eV by changing the compressive strain of a microdot ceria-based phase by more than 1.16%. The electrical conductivity data is analyzed and interpreted with a strain volume model and defect thermodynamics. Additionally, an equivalent circuit model is presented for sideways contacted multilayer microdots. We give a proof-of-concept for microdot contacting to capture real strain-ionic transport effects and reveal that for classic top-electrode contacting the effect is nil, highlighting the need for sideways electric contacting on a nanoscopic scale. The near order ionic transport interaction is supported by Raman spectroscopy measurements. These were conducted and analyzed together with fully relaxed single thin film samples. Strain states are described relative to the strain activated volumes of Gd0.1Ce0.9O(2-δ) in the microdot multilayer. These findings reveal that strain engineering in microfabricated devices allows altering the ionic conduction over a wide range beyond classic doping strategies for single films. The reported fabrication route and concept of strained multilayer microdots is a promising path for applying strained multilayer oxides as active new building blocks relevant for a broad range of microelectrochemical devices, e.g., resistive switching memory prototypes, resistive or electrochemical sensors, or as active catalytic solid state surface components for microfuel cells or all-solid-state batteries.

When two become one: An insight into 2D conductive oxide interfaces

“…This approach represents a novel concept which, as also recently proposed for other defective oxides [69,70,123], could be already applied e.g. in strain-activated memristors or other applications where MIEC is desirable.…”

“…by varying the number of individual layers from 1 to 60 nm while keeping the microdot at a constant thickness [123]. Electrical measurements showed that the activation energy of the devices could be altered by 0.31 eV and the conductivity decreased by one order of magnitude [123].…”

“…Electrical measurements showed that the activation energy of the devices could be altered by 0.31 eV and the conductivity decreased by one order of magnitude [123]. …”

Edge dislocation slows down oxide ion diffusion in doped CeO2 by segregation of charged defects

“…Elastic strain is considered as a new knob to enhance the performance of oxide electrochemical devices, including solid oxide fuel cells (SOFCs) [9][10][11] , photocatalysts 22 , batteries 23 , electrolysers 24 and redox-based resistive memories 25 , by accelerating ion conduction. However, in most of these studies, the influence of strain was interpreted in terms of elastic strain alone, while plastic strain, that is, strain accommodated by dislocations, has been overlooked.…”

Interfacial Strain Mapping and Chemical Analysis of Strained-Interface Heterostructures by Nanodiffraction and Electron Energy-Loss Spectroscopy

“…Interfacial strain control of electrical conductivity [1] and resistive switching [2] was reported for sideways-contacted Gd0.1Ce0.9O2-δ|Er2O3 (GCO|ERO) 'microdot' heterostructures with alternating monolayers of insulating ERO and mixed-conducting GCO, whose lattice mismatch yielded compressive strain in the GCO layers. Here we explore these and other GCO heterostructures with alternative straining oxides that impart varying degrees of tensile strain on GCO, such as Bi4NbO8.5|GCO (BNO|GCO).…”