On the emergence of conductivity at SrTiO3-based oxide interfaces – an in-situ study

Soosten, Merlin von; Christensen, Dennis Valbjørn; Eom, Chang‐Beom; Jespersen, Thomas Sand; Chen, Yunzhong; Pryds, Nini

doi:10.1038/s41598-019-54463-w

Cited by 13 publications

(20 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This ensures that our simulations allow general conclusions on the oxygen vacancy redistribution, although the exact initial distribution is unknown. By choosing this state as a starting point for our simulations, we also assume that the oxygen transfer between the oxygen scavenging layer and the SrTiO 3 substrate has already taken place during sample preparation [31,54]. After sample preparation, the rate of oxygen transfer is expected to become insignificant, because the sheet carrier density in such samples typically remains constant over long periods of time [41,47].…”

Section: A Initial Statementioning

confidence: 99%

“…While there are other studies [19,[21][22][23]31,33,41,50,[52][53][54] that report changes in the oxygen vacancy profile at SrTiO 3 -based heterointerfaces, the involved dynamics of ions in a complex energy landscape, with strong concentration gradients and intrinsic electric fields, has not been discussed in detail yet. Consequently, several questions remain unclear: What are the driving forces involved in the oxygen vacancy redistribution?…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Dynamics of the spatial separation of electrons and mobile oxygen vacancies in oxide heterostructures

Zurhelle

Christensen

Menzel

et al. 2020

Phys. Rev. Materials

View full text Add to dashboard Cite

In the search for an oxide-based 2D electron system with a large concentration of highly mobile electrons, a promising strategy is to introduce electrons through donor doping while spatially separating electrons and donors to prevent scattering. In SrTiO 3 , this can be achieved by tailoring the oxygen vacancy profile through reduction, e.g., by creating an interface with an oxygen scavenging layer. Through reduction, oxygen atoms are removed close to the interface, leaving behind oxygen vacancies in the SrTiO 3 lattice and mobile electrons in the SrTiO 3 conduction band. The commonly assumed picture is that the oxygen vacancies then remain confined close to the interface while the electrons leak a few nanometers into the bulk, resulting in an electron-defect separation and a highly mobile, oxide-based 2D electron system. So far it has remained unclear how the confinement and electron-defect separation develop over time. Here, we present transient finite element simulations that consider three driving forces acting on the oxygen vacancy distribution: diffusion due to the concentration gradient, drift due to the intrinsic electric field, and an oxygen vacancy trapping energy that holds oxygen vacancies at the interface. Our simulations show that at room temperature, three distinct regions are formed in SrTiO 3 within days: (1) Oxygen vacancies are partially held at the interface due to the oxygen vacancy trapping energy. (2) The accompanying positive space charge causes an oxygen vacancy depletion layer with large electron concentration and high mobility just below the interface. This electron-defect separation, indeed, leads to a highly conductive region. (3) While we are able to describe measured conductivity data with an oxygen vacancy trapping energy of −0.2 eV, this value does not prevent oxygen vacancy diffusion into the bulk: A diffusion front progresses into the bulk and leads to significant conductivity arising over the first micrometer within a couple of months. An enhanced oxygen vacancy trapping energy of −0.5 eV or below would suppress this loss of confinement, leading to a static and pronounced electron-defect separation. Consequently, our results highlight the importance of oxygen vacancy redistribution and suggest the trapping energy of oxygen vacancies at the interface as an important design parameter for oxygen-vacancy-based 2D electron systems.

show abstract

Section: A Initial Statementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dynamics of the spatial separation of electrons and mobile oxygen vacancies in oxide heterostructures

Zurhelle

Christensen

Menzel

et al. 2020

Phys. Rev. Materials

View full text Add to dashboard Cite

show abstract

“…Several studies also investigate the effect of the particle bombardment along with other stimuli occurring during the PLD . This can be done by measuring the conductivity of the STO‐based heterostructure in real‐time during the deposition.…”

Section: Other Factors: Adsorbates Particle Bombardment and Temperamentioning

confidence: 99%

“…The real‐time monitoring of the conductivity in STO‐based heterostructures offers the potential for tailoring the conductivity on‐the‐fly by in situ switching from one target to another or by varying the deposition conditions . Combined with other in situ characterization techniques such as reflective high‐energy electron diffraction and XPS, this is a powerful method for achieving the desired properties of heterostructures.…”

Section: Other Factors: Adsorbates Particle Bombardment and Temperamentioning

confidence: 99%

Stimulating Oxide Heterostructures: A Review on Controlling SrTiO₃‐Based Heterointerfaces with External Stimuli

Christensen

Trier

Niu

et al. 2019

Adv Materials Inter

Self Cite

View full text Add to dashboard Cite

Oxides are an exciting class of electronic materials which share key properties with conventional semiconductors, but also bring new intrinsic functionalities that are not used in most current electronics: superconductivity, ferro-, pyro-, and piezoelectricity, ferromagnetism, and multiferrocity. Among the large number of oxides, strontium titanate (SrTiO 3 , STO) has been the center of attention in numerous studies for more than half a century. STO both serves as a popular template for epitaxial growth of oxide thin films as well as by itself exhibiting an attractive palettes of properties, including Numerous of the greatest inventions in modern society, such as solar cells, display panels, and transistors, rely on a simple concept: An external stimulus is applied to a material and the response is then utilized. Oxides often exhibit a colorful palette of responses to external stimuli due to the close coupling between lattice, spin, orbital, and charge degrees of freedom. In particular, oxide heterostructures where oxide thin films are deposited on SrTiO 3 have proven to be a fertile playground for material scientists, and a vast amount of interesting theoretical and experimental studies showcase the wide tunabilities of these heterostructures when subjected to external stimuli. Here, the authors review how the properties of SrTiO 3 -based heterostructures can be changed by external stimuli using electric fields, magnetic fields, light, stress, particle bombardment, liquids, gases, and temperature. The application of a single stimulus or several stimuli combined often leads to unexpected changes in properties which can open up for designing new devices as well as expanding the boundaries of our understanding within fundamental science. Hall of Fame Article is a research scientist at the Technical University of Denmark, Department of Energy Conversion and Storage. He received his B.Sc. (2009) and M.Sc. (2012) in nanoscience from the University of Copenhagen, followed by his Ph.D. (2017) and postdoc (2018) from the Technical University of Denmark. His work is currently focused on the physics of oxide materials and oxide devices for information technology and energy harvesting, including oxide electronics, memristors, internet of things, and thermoelectricity. Felix Trier is a postdoctoral researcher at CNRS/Thales, University Paris-Saclay. He obtained his B.Sc. (2009) and M.Sc. (2012) in nanoscience from the University of Copenhagen. Then he earned his Ph.D. degree (2016) from the Technical University of Denmark. His current research is focused on fabrication and characterization of metallic oxide heterointerface devices for the study of the spin-charge interconversion in 2D Rashba systems. His work concerns the LaAlO 3 /SrTiO 3 heterointerface 2D metal and its electrostatic tunability.Nini Pryds is a Professor and head of the research section "Functional Oxides" at the Department of Energy Conversion and Storage, Technical University of Denmark (DTU), where he is leading a group of researchers working in the field...

show abstract

“…[ 2 ] These features render STO a crucial material for the implementation of oxide‐based electronics. [ 3 ] Quickly after the report on the remarkable transport properties emerging at the LAO/STO interface [ 1 ] and other STO‐based heterostructures, [ 4 , 5 , 6 , 7 ] a 2DEG was directly observed by angle‐resolved photoemission (ARPES) on the surface of bare STO, [ 8 , 9 ] renewing the interest in the basic physics of this material.…”

Section: Introductionmentioning

confidence: 99%

Universal Structural Influence on the 2D Electron Gas at SrTiO₃ Surfaces

et al. 2021

View full text Add to dashboard Cite

The 2-dimensional electron gas (2DEG) found at the surface of SrTiO 3 and related interfaces has attracted significant attention as a promising basis for oxide electronics. In order to utilize its full potential, the response of this 2DEG to structural changes and surface modification must be understood in detail. Here, a study of the detailed electronic structure evolution of the 2DEG as a function of sample temperature and surface step density is presented. By comparing the experimental results with ab initio calculations, it is shown that local structure relaxations cause a metal-insulator transition of the system around 135 K. This study presents a new and simple way of tuning the 2DEG via surface vicinality and identifies how the operation of prospective devices will respond to changes in temperature.

show abstract

On the emergence of conductivity at SrTiO3-based oxide interfaces – an in-situ study

Cited by 13 publications

References 35 publications

Dynamics of the spatial separation of electrons and mobile oxygen vacancies in oxide heterostructures

Dynamics of the spatial separation of electrons and mobile oxygen vacancies in oxide heterostructures

Stimulating Oxide Heterostructures: A Review on Controlling SrTiO₃‐Based Heterointerfaces with External Stimuli

Universal Structural Influence on the 2D Electron Gas at SrTiO₃ Surfaces

Contact Info

Product

Resources

About

On the emergence of conductivity at SrTiO3-based oxide interfaces – an in-situ study

Cited by 13 publications

References 35 publications

Dynamics of the spatial separation of electrons and mobile oxygen vacancies in oxide heterostructures

Dynamics of the spatial separation of electrons and mobile oxygen vacancies in oxide heterostructures

Stimulating Oxide Heterostructures: A Review on Controlling SrTiO3‐Based Heterointerfaces with External Stimuli

Universal Structural Influence on the 2D Electron Gas at SrTiO3 Surfaces

Contact Info

Product

Resources

About

Stimulating Oxide Heterostructures: A Review on Controlling SrTiO₃‐Based Heterointerfaces with External Stimuli

Universal Structural Influence on the 2D Electron Gas at SrTiO₃ Surfaces