Local structure of the crystalline and amorphous states of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Ga</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Te</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math>phase-change alloy without resonant bonding: A combined x-ray absorption and<i>ab initio</i>study

Kolobov, Alexander V.; Fons, Paul; Krbal, Miloš; Mitrofanov, Kirill V.; Tominaga, Junji; Uruga, Tomoya

doi:10.1103/physrevb.95.054114

Cited by 14 publications

(13 citation statements)

References 71 publications

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“…[ 15 ] The GaTe binary compounds at the three known compositions, GaTe,

{Ga}_{2} {Te}_{3}

, and

{Ga}_{2} {Te}_{5}

, also crystallize in a tetrahedral‐like geometry for Ga atoms. [ 16–18 ] On the contrary, simulations based on density functional theory (DFT) showed that the tetrahedral coordination of Ga atoms and the octahedral/pyramidal coordinations of Sb and Te atoms present in the crystalline binary parent compounds survive in the amorphous phase of the ternary compound. [ 19 ] It is therefore of interest to uncover which local configuration would be present in crystalline

{Ga}_{4} {Sb}_{6} {Te}_{3}

.…”

Section: Figurementioning

confidence: 99%

First‐Principles Study on the Crystalline Ga₄Sb₆Te₃ Phase Change Compound

Baratella

Dragoni

Ceresoli³

et al. 2020

Physica Rapid Research Ltrs

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The Ga4Sb6Te3 compound on the GaSb–Sb2Te3 pseudobinary tie‐line is proposed in the literature as a phase change material with high crystallization temperature. Herein, the crystal structure of this compound is uncovered by means of a genetic algorithm and electronic structure calculations based on density functional theory. As opposed to the parent GaSb compound which crystallizes in the zincblende structure, the Ga4Sb6Te3 compound features an octahedral‐like coordination for Ga as well as for Sb and Te atoms. Other structures close in energy to the ground state are also proposed, including some with a tetrahedral‐like coordination of Ga atoms. Raman spectra computed within density functional perturbation theory and an empirical Bond Polarizability Model are shown to be able to discriminate among the different possible local environments of Ga atoms.

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“…[ 15 ] The GaTe binary compounds at the three known compositions, GaTe,

{Ga}_{2} {Te}_{3}

, and

{Ga}_{2} {Te}_{5}

{Ga}_{4} {Sb}_{6} {Te}_{3}

.…”

Section: Figurementioning

confidence: 99%

First‐Principles Study on the Crystalline Ga₄Sb₆Te₃ Phase Change Compound

Baratella

Dragoni

Ceresoli³

et al. 2020

Physica Rapid Research Ltrs

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“…Stoichiometric vacancies of the Ga atom exist in the one-third of cation sites due to the valence mismatch between a cation and an anion. [9,10] Thus, Ga 2 Te 3 has many valence alternation pairs because of the vacancy diffusion, which is suitable for ovonic threshold switching (OTS) materials. [10] Furthermore, it has been reported that amorphous Ga 2 Te 3 (a-Ga 2 Te 3 ) shows OTS characteristics with high reliability.…”

Section: Introductionmentioning

confidence: 99%

“…[9,10] Thus, Ga 2 Te 3 has many valence alternation pairs because of the vacancy diffusion, which is suitable for ovonic threshold switching (OTS) materials. [10] Furthermore, it has been reported that amorphous Ga 2 Te 3 (a-Ga 2 Te 3 ) shows OTS characteristics with high reliability. [11] OTS characteristics are affected by the interplay of the bandgap, trap state, electron affinity, and electrode materials.…”

Section: Introductionmentioning

confidence: 99%

Effect of Zr Addition on Threshold Switching Characteristics of Amorphous Ga₂Te₃ Thin Films

Lee

Kim

et al. 2020

Physica Status Solidi (a)

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A cross‐point array structure is a promising structure in high‐density memory applications. However, a cross‐point array has sneak current paths from selected cells to neighboring unselected cells, and a selector device is required to suppress the sneak current issue. Therefore, the capability of modulating the threshold voltage is one of the essential elements facilitating reliable operation of the cross‐point array structure. Herein, the effect of Zr doping on the threshold switching properties of amorphous Ga2Te3 (a‐Ga2Te3) thin films is investigated with optical and electrical properties and the thermal stability of amorphous phase. Zr‐doped a‐Ga2Te3 thin films increase the threshold and holding voltages with improved thermal stability. Moreover, Zr doping reduces the leakage current of the Ga2Te3 selector device, which is beneficial to implement the cross‐point array of high density. Regarding the endurance, Zr‐doped a‐Ga2Te3 thin films show stable operation until 109 cycles.

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“…23,32−36 Nevertheless, some authors argued that there are other compounds of phase change materials (Ga 2 Te 3 ) with a tetrahedral-like environment in the metastable crystalline phase. 37,38 This would exclude resonant bonding as the reason for the large optical contrast. However, only the successful phase change and a good electrical contrast were reported, while the optical properties of the samples were not thoroughly studied.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Because of the octahedral-like environment of the atoms, only these compositions show pronounced resonant bonding in the metastable crystalline state, which seems to be the reason for the high optical contrast. Since then, many authors have accepted the model of resonant bonding that seems to be crucial for the high optical contrast of phase change materials. ,− Nevertheless, some authors argued that there are other compounds of phase change materials (Ga 2 Te 3 ) with a tetrahedral-like environment in the metastable crystalline phase. , This would exclude resonant bonding as the reason for the large optical contrast. However, only the successful phase change and a good electrical contrast were reported, while the optical properties of the samples were not thoroughly studied.…”

Section: Introductionmentioning

confidence: 99%

Investigating the Influence of Resonant Bonding on the Optical Properties of Phase Change Materials (GeTe)_xSnSb₂Se₄

et al. 2017

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Thin film samples of Ge 9 SnSb 2 Te 9 Se 4 , Ge 4.5 SnSb 2 Te 4.5 Se 4 , Ge 2.5 SnSb 2 Te 2.5 Se 4 , and GeSnSb 2 TeSe 4 were prepared via co-sputtering of GeTe and SnSb 2 Se 4 and compared to the well-investigated phase change material GeTe. All samples were obtained in an amorphous state. Temperature-dependent in situ X-ray diffraction experiments reveal a crystallization temperature that increases with an increasing SnSb 2 Se 4 content, leading to a higher stability of the amorphous phase. The electrical contrast between the amorphous and metastable crystalline state investigated via the van der Pauw method is as large as 4 orders of magnitude up to a 4.5:1 GeTe:SnSb 2 Se 4 ratio. Increasing the SnSb 2 Se 4 content leads to a decrease in the electrical contrast. Investigations of the samples by applying Fourier transform infrared spectroscopy and variable incident angle spectroscopic ellipsometry show that the optical properties of the amorphous phase are not affected by changes in stoichiometry. In striking contrast, the impact of SnSb 2 Se 4 on the optical properties of the crystalline phases is significant: all optical constants decrease because of the reduction in the level of resonant bonding, which leads to a reduced absolute reflectivity of the crystalline phase resulting in a decrease in the optical contrast. These results support the assumption that resonant bonding is crucial for successful optical phase change memory materials.

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Local structure of the crystalline and amorphous states ofGa2Te3phase-change alloy without resonant bonding: A combined x-ray absorption andab initiostudy

Cited by 14 publications

References 71 publications

First‐Principles Study on the Crystalline Ga₄Sb₆Te₃ Phase Change Compound

First‐Principles Study on the Crystalline Ga₄Sb₆Te₃ Phase Change Compound

Effect of Zr Addition on Threshold Switching Characteristics of Amorphous Ga₂Te₃ Thin Films

Investigating the Influence of Resonant Bonding on the Optical Properties of Phase Change Materials (GeTe)_xSnSb₂Se₄

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Local structure of the crystalline and amorphous states ofGa2Te3phase-change alloy without resonant bonding: A combined x-ray absorption andab initiostudy

Cited by 14 publications

References 71 publications

First‐Principles Study on the Crystalline Ga4Sb6Te3 Phase Change Compound

First‐Principles Study on the Crystalline Ga4Sb6Te3 Phase Change Compound

Effect of Zr Addition on Threshold Switching Characteristics of Amorphous Ga2Te3 Thin Films

Investigating the Influence of Resonant Bonding on the Optical Properties of Phase Change Materials (GeTe)xSnSb2Se4

Contact Info

Product

Resources

About

First‐Principles Study on the Crystalline Ga₄Sb₆Te₃ Phase Change Compound

First‐Principles Study on the Crystalline Ga₄Sb₆Te₃ Phase Change Compound

Effect of Zr Addition on Threshold Switching Characteristics of Amorphous Ga₂Te₃ Thin Films

Investigating the Influence of Resonant Bonding on the Optical Properties of Phase Change Materials (GeTe)_xSnSb₂Se₄