Guideline to atomically flat TiO2-terminated SrTiO3(001) surfaces

Gellé, Florian; Chiriță, Roxana; Mertz, Damien; Rastei, M. V.; Dinia, A.; Colis, S.

doi:10.1016/j.susc.2018.06.001

Cited by 26 publications

(19 citation statements)

References 28 publications

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“…[53] However, our Kelvin probe force microscope (KPFM) measurements (Figure S3, Supporting Information) did not observe distinguishable different surface potential regions on the terraces, which suggests a homogeneous Sr, Ti and O distributions on both the terrace and the step regions. [54] Applying the Tr-STO substrate to the CVD process as reported, [45,55] we successfully grew high quality MoS 2 nanosheets with uniform triangular shape, as shown by the SEM image in Figure 1c as well as the AFM topographic image in Figure 1d (see Figure S4, Supporting Information for the corresponding phase image). Similar results on the relatively flatter substrate with lower steps are supplied in Figure S5 (Supporting Information).…”

Section: Fabrication Of Sl-mos 2 On the Trenched Srtio 3 (111) Substratementioning

confidence: 69%

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Modulated Photoluminescence of Single‐Layer MoS₂ via Nanostructured SrTiO₃ Surface

Huang

Chen

Wang

et al. 2022

Adv Materials Inter

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innovative devices such as synapse transistor, [15][16][17] nonvolatile memory, [18,19] nanopower generators, [20] and so on. For most application circumstances, a proper support is usually necessary which either holds the transferred MoS 2 thin film or directly serves as the synthetic substrate. In fact, recent studies have witnessed the effective modulation of the properties of the MoS 2 films rendered from the different supports. [21][22][23][24][25][26][27][28][29][30][31][32] On the one hand, distinct substrate materials can induce different charge separation at the interfaces and establish varied dipole fields at the corresponding heterojunctions, which strictly depends on the actual components as well as the atomic structures of the interfaces. [33,34] On the other hand, additional tuning effects can be obtained via nanostructuring the substrate surface, which has provided a more-open strategy for tuning the transportation and luminescence properties of MoS 2 . [35][36][37][38][39][40][41][42][43][44] However, in the latter case, the substrate surfaces were usually prepared through complicated and expensive processes such as nanosphere or electron beam lithographies. Meanwhile, onsite synthesis of the MoS 2 films has not been realized on these sophisticatedly structured substrates. The transfer process of the MoS 2 films inevitably arouses the formation of unwanted film wrinkles and interfacial contaminants, which hinders the optimization of the obtained heterostructures. [24,45] Nevertheless, direct synthesis of high quality 2DMs on the largely corrugated substrate remains an urgent yet challenging task. The structure and morphology of the substrate surface play critical roles in tuning the properties of the supported two-dimension materials (2DM). In this work, a simple strategy to engineer the SrTiO 3 single crystal into a trenched structure which is composed of atomically flat terraces and high steps of several nanometers is developed. Through the conventional chemical vapor deposition method, high quality single-layered MoS 2 nanosheets are successfully fabricated directly on the trenched SrTiO 3 (Tr-STO) substrate, which thus result in a heterostructure with well-defined interface and controllable corrugated morphology. The corrugated MoS 2 /Tr-STO sample displays a drastically suppressed photoluminescence as compared to those grown on atomically flat substrates. Detailed scanning probe microscopy in combination with optical spectroscopy measurements demonstrates that the photoluminescence quenching occurs exclusively in the MoS 2 area carpeting the high SrTiO 3 steps, which can be attributed to the significantly reduced bandgaps hence massively enriched free charges in these regions. This work not only provides a new strategy to tailor the 2DM properties by simply engineering the substrate surface corrugations, but also brings deep insights into the dependence of properties of the hybridized system on the interface morphologies.

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Section: Fabrication Of Sl-mos 2 On the Trenched Srtio 3 (111) Substratementioning

confidence: 69%

Section: Resultsmentioning

confidence: 99%

Modulated Photoluminescence of Single‐Layer MoS₂ via Nanostructured SrTiO₃ Surface

Huang

Chen

Wang

et al. 2022

Adv Materials Inter

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“…Three possible mechanisms are possible to cause such difference: termination-, reconstruction- or reduction-related. The first would be the termination variation within one terrace, with the higher WF values related to the TiO 2 termination, which is dominant, and the lower to the SrO-enriched terrace edges, as previous KPFM studies showed the difference between air-annealed SrTiO 3 terminations of ≈10 meV [41]. However, for the case of heavily reduced SrTiO 3 (100) the only observed termination is TiO 2 , given the step uniform heights of ≈4 Å.…”

Section: Resultsmentioning

confidence: 92%

Kelvin probe force microscopy work function characterization of transition metal oxide crystals under ongoing reduction and oxidation

Wrana¹,

Cieślik²,

Bełza³

et al. 2019

Beilstein J. Nanotechnol.

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Controlling the work function of transition metal oxides is of key importance with regard to future energy production and storage. As the majority of applications involve the use of heterostructures, the most suitable characterization technique is Kelvin probe force microscopy (KPFM), which provides excellent energetic and lateral resolution. In this paper, we demonstrate precise characterization of the work function using the example of artificially formed crystalline titanium monoxide (TiO) nanowires on strontium titanate (SrTiO3) surfaces, providing a sharp atomic interface. The measured value of 3.31(21) eV is the first experimental work function evidence for a cubic TiO phase, where significant variations among the different crystallographic facets were also observed. Despite the remarkable height of the TiO nanowires, KPFM was implemented to achieve a high lateral resolution of 15 nm, which is close to the topographical limit. In this study, we also show the unique possibility of obtaining work function and conductivity maps on the same area by combining noncontact and contact modes of atomic force microscopy (AFM). As most of the real applications require ambient operating conditions, we have additionally checked the impact of air venting on the work function of the TiO/SrTiO3(100) heterostructure, proving that surface reoxidation occurs and results in a work function increase of 0.9 eV and 0.6 eV for SrTiO3 and TiO, respectively. Additionally, the influence of adsorbed surface species was estimated to contribute 0.4 eV and 0.2 eV to the work function of both structures. The presented method employing KPFM and local conductivity AFM for the characterization of the work function of transition metal oxides may help in understanding the impact of reduction and oxidation on electronic properties, which is of high importance in the development of effective sensing and catalytic devices.

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“…This assignment is supported by the measured KPFM difference of air-annealed SrTiO3 terminations of approx. 10 meV [41]. This difference is not likely to be caused by the electronic depleted layer at step edges, since it stretches out from the edges up to 100 nm, which is too far to be attributed to local dipoles.…”

Section: Fig 4 Kpfm Lateral Resolution On High Tio/sto Structures A) Topography and B) Work Function Of Tio Nanowire Array On Srtio3(100)mentioning

confidence: 93%

KPFM work function characterization of ongoing reduction and oxidation of transition metal oxide crystals on examples of SrTiO₃ and TiO nanowires

Wrana¹,

Cieślik²,

Bełza³

et al. 2019

Preprint

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Controlling the work function of transition metal oxides is of key importance towards future energy production and storage. As majority of applications comprise the use of heterostructures, the most suitable experimental technique is Kelvin Probe Force Microscopy, providing excellent energetic and lateral resolution. In this paper we demonstrate the possibility of the precise work function characterization using the example of artificially formed crystalline titanium monoxide TiO nanowires on strontium titanate SrTiO3 surfaces providing a sharp atomic interface. The measured value of 3.31(21) eV is the first experimental work function evidence for a cubic TiO phase, being additionally subjected to significant variations among different crystallographic facets. Despite the remarkable height of the formed TiO nanowires, FM-KPFM proved to be able to achieve high lateral resolution of 15 nm, which is close to the topographical limits. In this study we show also the unique possibility of obtaining conductivity and work function maps on the same area, by combining contact and non-contact atomic force microscopy. As most of real applications require ambient operating conditions, we have additionally checked the impact of air venting on the work function of the TiO/SrTiO3(100) heterostructure, proving the surface re-oxidation occurs and results in work function increases of 0.9 eV and 0.6 eV for SrTiO3 and TiO, respectively. In addition, the influence of physisorbed species was estimated to contribute 0.4 eV and 0.2 eV to the work function of both structures. The presented method of the KPFM (and LC-AFM) employment for the work function characterization of transition metal oxides may help to understand the reduction and oxidation impact on electronic properties, which is of high importance towards the development of effective sensing and catalytic devices.

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Guideline to atomically flat TiO2-terminated SrTiO3(001) surfaces

Cited by 26 publications

References 28 publications

Modulated Photoluminescence of Single‐Layer MoS₂ via Nanostructured SrTiO₃ Surface

Modulated Photoluminescence of Single‐Layer MoS₂ via Nanostructured SrTiO₃ Surface

Kelvin probe force microscopy work function characterization of transition metal oxide crystals under ongoing reduction and oxidation

KPFM work function characterization of ongoing reduction and oxidation of transition metal oxide crystals on examples of SrTiO₃ and TiO nanowires

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Guideline to atomically flat TiO2-terminated SrTiO3(001) surfaces

Cited by 26 publications

References 28 publications

Modulated Photoluminescence of Single‐Layer MoS2 via Nanostructured SrTiO3 Surface

Modulated Photoluminescence of Single‐Layer MoS2 via Nanostructured SrTiO3 Surface

Kelvin probe force microscopy work function characterization of transition metal oxide crystals under ongoing reduction and oxidation

KPFM work function characterization of ongoing reduction and oxidation of transition metal oxide crystals on examples of SrTiO3 and TiO nanowires

Contact Info

Product

Resources

About

Modulated Photoluminescence of Single‐Layer MoS₂ via Nanostructured SrTiO₃ Surface

Modulated Photoluminescence of Single‐Layer MoS₂ via Nanostructured SrTiO₃ Surface

KPFM work function characterization of ongoing reduction and oxidation of transition metal oxide crystals on examples of SrTiO₃ and TiO nanowires