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

Marcin Wojtyniak,Katarzyna Balin,Jacek Szade,Krzysztof Szot

doi:10.3390/cryst10010033

Marcin Wojtyniak, Katarzyna Balin + Show 2 more

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https://doi.org/10.3390/cryst10010033

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Abstract

The effect of Fe doping on SrTiO3 single crystals was investigated in terms of crystal and electronic structure over a wide temperature range in both oxidizing and reducing conditions. The electrical properties were thoroughly studied with a special focus on the resistive switching phenomenon. Contrary to the undoped SrTiO3 crystals, where isolated filaments are responsible for resistive switching, the iron-doped crystals showed stripe-like conducting regions at the nanoscale. The results showed a non-uniform Fe distribution of as-received crystals and the formation of new phases in the surface layer of reduced/oxidized samples. The oxidation procedure led to a separation of Ti(Fe) and Sr, while the reduction resulted in the tendency of Fe to agglomerate and migrate away from the surface as seen from the time of flight mass spectroscopy measurements. Moreover, a clear presence of Fe-rich nano-filament in the reduced sample was found.

Highlights

The resistive switching (RS) phenomenon attracts growing interest, and is approaching the level of applied device implementation [1,2,3,4]
We have focused on the phase and chemistry of investigated crystals by X-ray Diffraction (XRD), X-ray Fluorescence
The as-received samples investigated by the XRD in standard geometry showed simple cubic

Summary

Introduction

The resistive switching (RS) phenomenon attracts growing interest, and is approaching the level of applied device implementation [1,2,3,4]. Attention towards the RS phenomena results from physical mechanisms that can be generally explained as a non-volatile change of the material resistivity under electrical stimuli. A wide variety of materials exhibit such behavior, efforts to reveal the nature of this mechanism and explore specific applications is widespread. Since the change of resistance in such materials is non-volatile and reversible, they are treated as prospective candidates for the development of non-volatile memory devices, next-generation logic devices and neuromorphic systems [2,3,4,5]. Among various materials remarkable advancements have been observed in the field of transition metal oxides [6,7,8]. SrTiO3 (STO) [9], between other ternary (or binary like TiO2 [10])

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