Inhomogeneity and Segregation Effect in the Surface Layer of Fe-Doped SrTiO3 Single Crystals

Wojtyniak, Marcin; Balin, Katarzyna; Szade, J.; Szot, K.

doi:10.3390/cryst10010033

Cited by 9 publications

(5 citation statements)

References 40 publications

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“…It is also known that with the thermally induced reduction of SrTiO 3 , the surface region becomes Ti-rich and eventually, titanium suboxides form [54,55]. Hence, the incipient phase transformation could lead to clustering effects on the nanoscale, resulting in the observed inhomogeneous photoluminescence lifetime distribution.…”

Section: Investigation Of Photoluminescencementioning

confidence: 99%

The Electronic Properties of Extended Defects in SrTiO3—A Case Study of a Real Bicrystal Boundary

et al. 2020

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This study investigates the impact of extended defects such as dislocations on the electronic properties of SrTiO3 by using a 36.8° bicrystal as a model system. In order to evaluate the hypothesis that dislocations can serve as preferential reduction sites, which has been proposed in the literature on the basis of ab initio simulations, as well as on experiments employing local-conductivity atomic force microscopy (LC-AFM), detailed investigations of the bicrystal boundary are conducted. In addition to LC-AFM, fluorescence lifetime imaging microscopy (FLIM) is applied herein as a complementary method for mapping the local electronic properties on the microscale. Both techniques confirm that the electronic structure and electronic transport in dislocation-rich regions significantly differ from those of undistorted SrTiO3. Upon thermal reduction, a further confinement of conductivity to the bicrystal boundary region was found, indicating that extended defects can indeed be regarded as the origin of filament formation. This leads to the evolution of inhomogeneous properties of defective SrTiO3 on the nano- and microscales.

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Section: Investigation Of Photoluminescencementioning

confidence: 99%

The Electronic Properties of Extended Defects in SrTiO3—A Case Study of a Real Bicrystal Boundary

et al. 2020

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“…This effect has been confirmed using a variety of techniques including secondary ion mass spectrometry (SIMS) and X-ray photoelectron spectroscopy (XPS) 7,28,32 . During the oxidation process, the segregation of Sr to the surface can lead to a local formation of Ruddlesden-Popper phases in the surface layer and eventually to the evolution of SrO islands on the surface.…”

Section: Resultsmentioning

confidence: 88%

Mapping the conducting channels formed along extended defects in SrTiO3 by means of scanning near-field optical microscopy

Rodenbücher

Bittkau

Bihlmayer

et al. 2020

Sci Rep

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Mixed ionic-electronic-conducting perovskites such as SrTiO3 are promising materials to be employed in efficient energy conversion or information processing. These materials exhibit a self-doping effect related to the formation of oxygen vacancies and electronic charge carriers upon reduction. It has been found that dislocations play a prominent role in this self-doping process, serving as easy reduction sites, which result in the formation of conducting filaments along the dislocations. While this effect has been investigated in detail with theoretical calculations and direct observations using local-conductivity atomic force microscopy, the present work highlights the optical properties of dislocations in SrTiO3 single crystals. Using the change in optical absorption upon reduction as an indicator, two well-defined arrangements of dislocations, namely a bicrystal boundary and a slip band induced by mechanical deformation, are investigated by means of scanning near-field optical microscopy. In both cases, the regions with enhanced dislocation density can be clearly identified as regions with higher optical absorption. Assisted by ab initio calculations, confirming that the agglomeration of oxygen vacancies significantly change the local dielectric constants of the material, the results provide direct evidence that reduced dislocations can be classified as alien matter embedded in the SrTiO3 matrix.

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“…Thus, it suggests that the conducting paths consisted of oxygen vacancies prefer to form around electrode edges, where higher concentration of defects more likely yield and agglomerate after device fabrication. [ 21,40–42 ] In addition, the strengthened electric field generated at the electrode edge produces significant contribution to the local breakdown of the Au electrode.…”

Section: Resultsmentioning

confidence: 99%

“…Meanwhile, the Sr‐enriched signals are evidently visible in regions uncovered by Au globules, indicating the occurrence of surface segregation of Sr in doped perovskite oxides. [ 16,42,43 ]…”

Section: Resultsmentioning

confidence: 99%

Nondestructive Visualization of Interfacial Conducting Inhomogeneities in Memristive Oxides by Electroluminescence

Lin

Dong

et al. 2020

Adv Materials Inter

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The formation of conducting paths consisting of oxygen vacancies plays a crucial role in the resistive switching (RS) phenomenon in oxides. However, it is extremely challenging to probe the dynamic distribution of oxygen vacancies under changing electric field without breaking the device. In this work, the temporal‐spatial variation of oxygen vacancies in memristive Nb‐SrTiO3 devices has been investigated nondestructively by defect states mediated electroluminescence (EL). The disparate spatial inhomogeneities of conducting paths penetrating the Au/Nb‐SrTiO3 interfaces are clearly demonstrated on the device scale, which is completely subject to the forming bias polarity. Moreover, the EL spectroscopy results confirm the existence of temporary nonequilibrium states in conducting paths. The causal relationship between the EL emission and oxygen vacancies concentration paves a pathway to explore RS dynamics in oxides, and further to design novel electro‐optical devices.

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Inhomogeneity and Segregation Effect in the Surface Layer of Fe-Doped SrTiO3 Single Crystals

Cited by 9 publications

References 40 publications

The Electronic Properties of Extended Defects in SrTiO3—A Case Study of a Real Bicrystal Boundary

The Electronic Properties of Extended Defects in SrTiO3—A Case Study of a Real Bicrystal Boundary

Mapping the conducting channels formed along extended defects in SrTiO3 by means of scanning near-field optical microscopy

Nondestructive Visualization of Interfacial Conducting Inhomogeneities in Memristive Oxides by Electroluminescence

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