Laser induced structural transformation in chalcogenide based superlattices

Zallo, Eugenio; Wang, Ruining; Bragaglia, Valeria; Calarco, Raffaella

doi:10.1063/1.4953158

Cited by 15 publications

(16 citation statements)

References 29 publications

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“…[18][19][20] The spectrum of the SL clearly features a superposition of the modes present in the constituent materials. 21 The A 1g modes in the SLs are slightly shifted with respect to their corresponding ones in Sb 2 Te 3 , as found also for GeTe-SLs. 10 The broadening of the Raman modes could be attributed to the presence of structural disorder due to imperfect stacking of the SL building blocks with respect to the stoichiometric Sb 2 Te 3 .…”

confidence: 68%

Improved structural and electrical properties in native Sb2Te3/GexSb2Te3+x van der Waals superlattices due to intermixing mitigation

et al. 2017

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Superlattices made of Sb2Te3/GeTe phase change materials have demonstrated outstanding performance with respect to GeSbTe alloys in memory applications. Recently, epitaxial Sb2Te3/GeTe superlattices were found to feature GexSb2Te3+x blocks as a result of intermixing between constituting layers. Here we present the epitaxy and characterization of Sb2Te3/GexSb2Te3+x van der Waals superlattices, where GexSb2Te3+x was intentionally fabricated. X-ray diffraction, Raman spectroscopy, scanning transmission electron microscopy, and lateral electrical transport data are reported. The intrinsic 2D nature of both sublayers is found to mitigate the intermixing in the structures, significantly improving the interface sharpness and ultimately the superlattice structural and electrical properties.

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confidence: 68%

Improved structural and electrical properties in native Sb2Te3/GexSb2Te3+x van der Waals superlattices due to intermixing mitigation

et al. 2017

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“…Raman spectroscopy was demonstrated to be suitable to identify the different crystalline phases of GST and to qualitatively access the vertical order in Sb 2 Te 3 /GeTe(GeSbTe) SLs . Interestingly, in the case of Sb 2+ x Te 3 this technique demonstrates excellent sensitivity to the structural changes induced by the excess of Sb, as shown in Figure a for the samples on normal Si.…”

Section: Raman Spectroscopymentioning

confidence: 99%

Interplay between Structural and Thermoelectric Properties in Epitaxial Sb₂₊_xTe₃ Alloys

Cecchi

Dragoni

Kriegner

et al. 2018

Adv Funct Materials

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In recent years strain engineering is proposed in chalcogenide superlattices (SLs) to shape in particular the switching functionality for phase change memory applications. This is possible in Sb 2 Te 3 /GeTe heterostructures leveraging on the peculiar behavior of Sb 2 Te 3 , in between covalently bonded and weakly bonded materials. In the present study, the structural and thermoelectric (TE) properties of epitaxial Sb 2+x Te 3 films are shown, as they represent an intriguing option to expand the horizon of strain engineering in such SLs. Samples with composition between Sb 2 Te 3 and Sb 4 Te 3 are prepared by molecular beam epitaxy. A combination of X-ray diffraction and Raman spectroscopy, together with dedicated simulations, allows unveiling the structural characteristics of the alloys. A consistent evaluation of the structural disorder characterizing the material is drawn as well as the presence of both Sb 2 and Sb 4 slabs is detected. A strong link exists among structural and TE properties, the latter having implications also in phase change SLs. A further improvement of the TE performances may be achieved by accurately engineering the intrinsic disorder. The possibility to tune the strain in designed Sb 2+x Te 3 /GeTe SLs by controlling at the nanoscale the 2D character of the Sb 2+x Te 3 alloys is envisioned.

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“…22 By comparing the spectra, it emerges that the yellow and blue curves in Fig. 1(d) are assigned to cand t-GST, respectively, 21,25 while the green curve corresponds to the mixed phases.…”

Section: Resultsmentioning

confidence: 99%

Designing epitaxial GeSbTe alloys by tuning the phase, the composition, and the vacancy ordering

Bragaglia

Arciprete

Mio

et al. 2018

Journal of Applied Physics

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In this study, we present a significant advance in the growth of epitaxial GeTe-Sb2Te3 alloys on Si(111)-(√3 × √3)R30°-Sb reconstructed surface by means of Molecular Beam Epitaxy. By employing X-ray diffraction and Raman spectroscopy, we show how phase, composition, and vacancy ordering can be tailored by tuning the growth parameters such as Ge and Te elemental fluxes as well as the substrate temperature. The effect of each parameter on the GeSbTe composition and phase is also discussed. A very surprising finding is that GeSbTe alloys are more ordered when grown at lower substrate temperatures. In addition, it was possible to fabricate ordered GeSbTe even for substrate temperatures as low as 120 °C. In situ high-energy electron diffraction is employed to monitor the crystallinity and surface roughness of GeSbTe films at different stages of growth. Thus, we identify the deposition parameter ranges whereby high structural quality GeSbTe with flat surfaces can be obtained.

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Laser induced structural transformation in chalcogenide based superlattices

Cited by 15 publications

References 29 publications

Improved structural and electrical properties in native Sb2Te3/GexSb2Te3+x van der Waals superlattices due to intermixing mitigation

Improved structural and electrical properties in native Sb2Te3/GexSb2Te3+x van der Waals superlattices due to intermixing mitigation

Interplay between Structural and Thermoelectric Properties in Epitaxial Sb₂₊_xTe₃ Alloys

Designing epitaxial GeSbTe alloys by tuning the phase, the composition, and the vacancy ordering

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Laser induced structural transformation in chalcogenide based superlattices

Cited by 15 publications

References 29 publications

Improved structural and electrical properties in native Sb2Te3/GexSb2Te3+x van der Waals superlattices due to intermixing mitigation

Improved structural and electrical properties in native Sb2Te3/GexSb2Te3+x van der Waals superlattices due to intermixing mitigation

Interplay between Structural and Thermoelectric Properties in Epitaxial Sb2+xTe3 Alloys

Designing epitaxial GeSbTe alloys by tuning the phase, the composition, and the vacancy ordering

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Interplay between Structural and Thermoelectric Properties in Epitaxial Sb₂₊_xTe₃ Alloys