Thermal conductivity of chalcogenide material with superlatticelike structure

Tong, Hao; Miao, Xiangshui; Cheng, Xiaomin; Wang, H.; Zhang, L.; Sun, Jiyu; Tong, Fei; Wang, J. H.

doi:10.1063/1.3562610

Cited by 34 publications

(25 citation statements)

References 20 publications

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“…The 12-layered SLL device was found to have the lowest RESET current. Several explanations such as decreased thermal conductivity due to layering 10 and reduction of entropy losses 9 have been proposed for the current reduction exhibited in multi-layered PCRAM devices. This debate is ongoing and is not the focus of this work.…”

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confidence: 99%

“…These SLL PCRAM cells demonstrated lower RESET currents with faster write/erase speeds compared to conventional GST PCRAM cells, and the improvements have fueled a growing interest in understanding and improving the SLL structure. 9,10 Despite SLL structures displaying reduced currents, SLL structures are expected to have poorer endurance/reliability since phase change materials with different material properties (such as stoichiometric composition and lattice constants) are used to create the SLL. SLL layers with different stoichiometry could drive inter-layer diffusion while the different lattice constants will increase crystallization-induced stress thus impacting the reliability of SLL PCRAMs.…”

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confidence: 99%

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Compositionally matched nitrogen-doped Ge2Sb2Te5/Ge2Sb2Te5 superlattice-like structures for phase change random access memory

Tan

Shi

Zhao

et al. 2013

Applied Physics Letters

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A compositionally matched superlattice-like (SLL) structure comprised of Ge2Sb2Te5 (GST) and nitrogen-doped GST (N-GST) was developed to achieve both low current and high endurance Phase Change Random Access Memory (PCRAM). N-GST/GST SLL PCRAM devices demonstrated ∼37% current reduction compared to single layered GST PCRAM and significantly higher write/erase endurances of ∼108 compared to ∼106 for GeTe/Sb2Te3 SLL devices. The improvements in endurance are attributed to the compositionally matched N-GST/GST material combination that lowers the diffusion gradient between the layers and the lower crystallization-induced stress in the SLL as revealed by micro-cantilever stress measurements.

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confidence: 99%

mentioning

confidence: 99%

Compositionally matched nitrogen-doped Ge2Sb2Te5/Ge2Sb2Te5 superlattice-like structures for phase change random access memory

Tan

Shi

Zhao

et al. 2013

Applied Physics Letters

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“…The variation of the SLL layer thickness is known to have a strong correlation with the thermal conductivity of the SLL structure [8,9]. To study the size effects of the SLL dielectric, the rise in PT as a function of its thermal conductivity was investigated, as shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…In general, most superlattice materials with a higher number of interfaces (generated either by increasing the number of layers or reducing the thickness of each layer in a SLL material with a given thickness) have lower thermal conductivities [8,9]. Considering the low thermal conductivities achieved in superlattice structures [8][9][10], the SLL dielectric was modeled as a single material layer, and assumed to have a thermal conductivity that is 50 % of that of the SiO 2 dielectric. We have also varied the thermal conductivity of the SLL dielectric to study the general effect of the SLL dielectric on the thermal properties of the PCRAM cell regardless of the layer numbers and thickness.…”

Section: Methodsmentioning

confidence: 99%

Nano Superlattice-like Materials as Thermal Insulators for Phase-Change Random Access Memory

et al. 2012

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Nanoscale superlattice-like (SLL) dielectric was employed to reduce the power consumption of the Phase-change random access memory (PCRAM) cells. In this study, we have simulated and found that the cells with the SLL dielectric have a higher peak temperature compared to that of the cells with the SiO 2 dielectric after constant pulse activation, due to the interface scattering mechanism. Scaling of the SLL dielectric has resulted in higher peak temperatures, which can be even higher after material/structural modifications. Furthermore, the SLL dielectric has good material properties that enable the cells to have high endurance. This shows the effectiveness of the SLL dielectric for advanced memory applications.

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“…Experimentally the phenomenon has been demonstrated, e.g., by Hicks et al in the PbTe/(Pb,Eu)Te system and by Ohta et al in the SrTiO 3 /Sr(Ti,Nb)O 3 system. Layered structures that show reduced thermal conductivity have been reported for a number of other material systems as well, such as CaTiO 3 /SrTiO 3 , W/Al 2 O 3 , PbTe/PbSe, IrSb 3 /CoSb 3 , AlN/GaN, TiNiSn/HfNiSn, Si/Ge (including alloy variants), GaAs/AlAs (including alloy variants), Bi 2 Te 3 /Sb 2 Te 3 , InAs/AlSb, InGaAs/InGaAsP, and Ge 2 Te 3 /Sb 2 Te 3 , to name a few. Most such inorganic–inorganic interfaces utilize isoelectronic substitution to retain the electrical conductivity and the high degree of crystallinity of the samples, which essentially grow epitaxially.…”

Section: Introductionmentioning

confidence: 87%

Thermal Conductivity Reduction at Inorganic–Organic Interfaces: From Regular Superlattices to Irregular Gradient Layer Sequences

Krahl

Giri

Tomko

et al. 2018

Adv Materials Inter

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been made by introducing disorder in the systems via alloying, complex crystal-engineering, [4,5] and by creating interfaces in thin films. [2] Hicks and Dresselhaus originally proposed that quantum well structures should be capable of lowering the thermal conductivity with only a minor impact on the electrical conductivity; [6] note that the latter point is particularly important for the application in thermoelectrics. Experimentally the phenomenon has been demonstrated, e.g., by Hicks et al. [7] in the PbTe/(Pb,Eu)Te system and by Ohta et al. [8] in the SrTiO 3 /Sr(Ti,Nb)O 3 system. Layered structures that show reduced thermal conductivity have been reported for a number of other material systems as well, such as CaTiO 3 /SrTiO 3 , [9] W/ Al 2 O 3 , [10] PbTe/PbSe, [11] IrSb 3 /CoSb 3 , [12] AlN/GaN, [13] TiNiSn/ HfNiSn, [14] Si/Ge (including alloy variants), [15][16][17][18][19] GaAs/AlAs (including alloy variants), [20][21][22][23] Bi 2 Te 3 /Sb 2 Te 3 , [24] InAs/AlSb, [25] InGaAs/InGaAsP, [26] and Ge 2 Te 3 /Sb 2 Te 3 , [27] to name a few. Most such inorganic-inorganic interfaces utilize isoelectronic substitution to retain the electrical conductivity and the high degree of crystallinity of the samples, which essentially grow epitaxially. An exception are the crystalline-amorphous interfaces as reported, e.g., in the Al 2 O 3 /TiO 2 [28] and Si [29] systems. With regard to high-quality interfaces, inorganic-organic superlattices offer an attractive option to reduce thermal conductivity compared to a homogeneous inorganic thin film. Owing to the large acoustic impedances between the inorganic and organic materials, we may anticipate considerably lowered thermal boundary conductance across the inorganic-organic interface. [30] Remarkable results have been reported for, e.g., TiS 2 with organic molecules intercalated either electrochemically [31] or chemically [32] from an organic solution. We have, on the other hand, fabricated ZnO/benzene [33,34] and TiO 2 /benzene [35,36] superlattices using the gas-phase atomic/molecular layer deposition (ALD/MLD) thin-film technique to demonstrate reductions in thermal conductivity of several orders of magnitude. Among the benefits of the ALD/MLD technique over solution-based intercalation routes is that it allows the precise control of the introduction frequency of the organic layers within the inorganic matrix.The uniting concept to lower the thermal conductivity of superlattice and nanolaminate structures is to suppress phonon Nanoscale superlattice structures are known to significantly suppress the thermal conductivity in thin films due to phonon scattering at the interfaces of the mutually different layers. Here it is demonstrated that in addition to the number of interfaces, their spacing within the film can lead to a reduction in thermal conductivity. The proof-of-concept data are for ZnO/benzene thin films fabricated through sequential gas-surface reactions in atomic/ molecular layer precision using the atomic/molecular layer deposition technique. In comparison to...

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Thermal conductivity of chalcogenide material with superlatticelike structure

Cited by 34 publications

References 20 publications

Compositionally matched nitrogen-doped Ge2Sb2Te5/Ge2Sb2Te5 superlattice-like structures for phase change random access memory

Compositionally matched nitrogen-doped Ge2Sb2Te5/Ge2Sb2Te5 superlattice-like structures for phase change random access memory

Nano Superlattice-like Materials as Thermal Insulators for Phase-Change Random Access Memory

Thermal Conductivity Reduction at Inorganic–Organic Interfaces: From Regular Superlattices to Irregular Gradient Layer Sequences

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