Optical properties of (GeTe, Sb2Te3) pseudobinary thin films studied with spectroscopic ellipsometry

Park, Jun Woo; Baek, Seoung Ho; Kang, Thomas H.‐K.; Lee, Hosun; Kang, Yu; Lee, Tae Yon; Suh, Dongseok; Kim, Ki Joon; Kim, Cheol Kyu; Khang, Yoonho; Silva, Juarez L. F. Da; Wei, Su‐Huai

doi:10.1063/1.2959818

Cited by 61 publications

(36 citation statements)

References 16 publications

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“…Fig. 4͒, our a-Sb 2 Te 3 model is semiconducting with a gap 0.69 eV large, in reasonable agreement with the Tauc band gap of 0.5 eV measured by Park et al 34 To quantify the localization properties of individual KS states, we have computed the IPR which is defined for the ith KS state by ͚ j c ij 4 / ͚͑ j c ij 2 ͒ 2 , where j runs over the Gaussian-type orbitals ͑GTOs͒ of the basis set and c ij are the expansion coefficients of the ith KS state in GTOs. IPRs are given in Fig.…”

Section: ͑1͒supporting

confidence: 92%

First-principles study of liquid and amorphousSb2Te3

2010

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Based on ab initio molecular-dynamics simulations, we generated models of liquid and amorphous Sb 2 Te 3 of interest for applications as phase change material in optical and electronic data storage. The local geometries of Sb and Te atoms in a-Sb 2 Te 3 are similar to that found in the extensively studied Ge 2 Sb 2 Te 5 and GeTe phase change materials already exploited for nonvolatile memory applications. Analysis of the vibrational properties and electronic structure of a-Sb 2 Te 3 is presented and compared to the crystalline counterparts.

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Section: ͑1͒supporting

confidence: 92%

First-principles study of liquid and amorphousSb2Te3

2010

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“…As the new states of quantum matter, three-dimensional topological insulators of the Bi 2 Te 3 family have also attracted much attention in recent years due to their unique electronic properties [9][10][11]. Since Sb 2 Te 3 is the prototypical PCM along the pseudobinary tie-line of Ge-Sb-Te alloys, and has been widely studied and applied [12][13][14][15], it is of great interest to explore whether Bi 2 Te 3 can also be a good candidate for PCM.…”

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confidence: 99%

Temperature dependence of structural, dynamical, and electronic properties of amorphous Bi₂Te₃: an ab initio study

et al. 2019

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Bismuth telluride (Bi 2 Te 3 ) has garnered significant interest in thermoelectric applications and threedimensional topological insulators due to its unique electronic, transport, and thermal properties. Bi 2 Te 3 and Sb 2 Te 3 chalcogenide compounds have the same crystal structure. While Sb 2 Te 3 has been shown to be a prototypical phase change memory (PCM) compound along the pseudobinary tie-line of Ge-Sb-Te alloys, whether Bi 2 Te 3 can also exhibit PCM functionality is still not well established. In this work, a systematic study on the structural, dynamical, and electronic properties of amorphous Bi 2 Te 3 during the quenching process has been performed by using ab initio molecular dynamics simulations. Pair correlation function, coordination number, bond-angle distribution functions, and a novel atomistic cluster alignment method are used to explore the structural characteristics of Bi 2 Te 3 as a function of temperature. Our study shows that there are many distorted octahedral clusters in amorphous Bi 2 Te 3 . In comparison with the local structures in Sb 2 Te 3 , we found that the degree of distortion of the octahedrons in the Bi 2 Te 3 system is smaller than that in Sb 2 Te 3 system. Moreover, the changes in the dynamical properties of Bi 2 Te 3 from liquid to glassy state are also explored. The approximate range of liquid-to-glass transition temperature is determined to be between 673 and 723 K. The electronic properties of Bi 2 Te 3 and Sb 2 Te 3 are also analysed by density-of-states and Bader charge calculations, both of them in glass state are semiconductors. Our studies provide useful insights into the local structure and dynamical properties of Bi 2 Te 3 at the atomistic level during the fast cooling process, and suggest that the compound can be a candidate for PCM materials.

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“…For the fabrication of GST thin films, magnetron sputtering12122, thermal (flash) evaporation2324, chemical vapor deposition using metal-organic precursors2526 or also atomic layer deposition27 can be used. In line with mentioned techniques, pulsed laser deposition (PLD) is a suitable deposition method for the thin films growth too.…”

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Pulsed laser deposited GeTe-rich GeTe-Sb2Te3 thin films

Bouška¹,

Péchev²,

Simon³

et al. 2016

Sci Rep

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Pulsed laser deposition technique was used for the fabrication of Ge-Te rich GeTe-Sb2Te3 (Ge6Sb2Te9, Ge8Sb2Te11, Ge10Sb2Te13, and Ge12Sb2Te15) amorphous thin films. To evaluate the influence of GeTe content in the deposited films on physico-chemical properties of the GST materials, scanning electron microscopy with energy-dispersive X-ray analysis, X-ray diffraction and reflectometry, atomic force microscopy, Raman scattering spectroscopy, optical reflectivity, and sheet resistance temperature dependences as well as variable angle spectroscopic ellipsometry measurements were used to characterize as-deposited (amorphous) and annealed (crystalline) layers. Upon crystallization, optical functions and electrical resistance of the films change drastically, leading to large optical and electrical contrast between amorphous and crystalline phases. Large changes of optical/electrical properties are accompanied by the variations of thickness, density, and roughness of the films due to crystallization. Reflectivity contrast as high as ~0.21 at 405 nm was calculated for Ge8Sb2Te11, Ge10Sb2Te13, and Ge12Sb2Te15 layers.

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Optical properties of (GeTe, Sb2Te3) pseudobinary thin films studied with spectroscopic ellipsometry

Cited by 61 publications

References 16 publications

First-principles study of liquid and amorphousSb2Te3

First-principles study of liquid and amorphousSb2Te3

Temperature dependence of structural, dynamical, and electronic properties of amorphous Bi₂Te₃: an ab initio study

Pulsed laser deposited GeTe-rich GeTe-Sb2Te3 thin films

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Optical properties of (GeTe, Sb2Te3) pseudobinary thin films studied with spectroscopic ellipsometry

Cited by 61 publications

References 16 publications

First-principles study of liquid and amorphousSb2Te3

First-principles study of liquid and amorphousSb2Te3

Temperature dependence of structural, dynamical, and electronic properties of amorphous Bi2Te3: an ab initio study

Pulsed laser deposited GeTe-rich GeTe-Sb2Te3 thin films

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Product

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Temperature dependence of structural, dynamical, and electronic properties of amorphous Bi₂Te₃: an ab initio study