Tailoring the Structural and Optical Properties of Germanium Telluride Phase-Change Materials by Indium Incorporation

Wang, Xudong; Shen, Xueyang; Sun, Suyang; Zhang, Wei

doi:10.3390/nano11113029

Cited by 12 publications

(4 citation statements)

References 100 publications

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“…As predicted by the MVB map (Figure 1a), amorphous As 2 Te 3 should undergo a fundamental change in bonding mechanism upon crystallization, which should lead to a strong change in optical properties. Here, we computed the frequency-dependent dielectric functions with independent-particle approximation [77][78][79][80] for both amorphous and crystalline As 2 Te 3 and Sb 2 Te 3 . The reflectivity R(ω) was calculated as the following.…”

Section: Resultsmentioning

confidence: 99%

Bonding Nature and Optical Properties of As₂Te₃ Phase‐Change Material

Sun

Zhu

Zhang

2022

Physica Rapid Research Ltrs

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Chalcogenide phase‐change materials (PCMs) are a promising candidate for advanced memory and computing technologies. PCM‐based random access memories have entered the global memory market as storage‐class memory. In these products, the element arsenic plays an essential role in the selector layers, but how arsenic stabilizes the thermal stability of the chalcogenide glass remains elusive. Herein, thorough ab initio simulations are carried out to understand the chemical bonding, electronic structure, and optical properties of an important arsenic alloy As2Te3 in both crystalline and amorphous forms. In comparison with the homologue alloy Sb2Te3, the importance of homopolar bonds in stabilizing the amorphous phase of As2Te3 is revealed. Also, a strategy for the design of As x Sb2−x Te3 alloys with optimal material properties for nonvolatile photonic phase‐change applications is proposed.

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Section: Resultsmentioning

confidence: 99%

Bonding Nature and Optical Properties of As₂Te₃ Phase‐Change Material

Sun

Zhu

Zhang

2022

Physica Rapid Research Ltrs

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“…The frequency-dependent dielectric matrix was calculated within the independent-particle approximation using VASP, which was shown to be adequate to account for the optical contrast between crystalline and amorphous PCMs. [100][101][102][103] The relaxed structures were calculated with the Quantum ESPRESSO code, [104] which provided ground-state wave-functions for the bonding analysis using the Critic2 code. [105] The Critic2 code calculates the domain overlap matrices (DOM) over Bader's basins, and the delocalization or localization indices (DIs/LIs) among or within such basins measure the quantity of electrons being localized in the atomic basin or shared between the two atoms.…”

Section: Methodsmentioning

confidence: 99%

Metavalent Bonding in Layered Phase‐Change Memory Materials

Zhang

Sun

et al. 2023

Advanced Science

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Metavalent bonding (MVB) is characterized by the competition between electron delocalization as in metallic bonding and electron localization as in covalent or ionic bonding, serving as an essential ingredient in phase‐change materials for advanced memory applications. The crystalline phase‐change materials exhibits MVB, which stems from the highly aligned p orbitals and results in large dielectric constants. Breaking the alignment of these chemical bonds leads to a drastic reduction in dielectric constants. In this work, it is clarified how MVB develops across the so‐called van der Waals‐like gaps in layered Sb2Te3 and Ge–Sb–Te alloys, where coupling of p orbitals is significantly reduced. A type of extended defect involving such gaps in thin films of trigonal Sb2Te3 is identified by atomic imaging experiments and ab initio simulations. It is shown that this defect has an impact on the structural and optical properties, which is consistent with the presence of non‐negligible electron sharing in the gaps. Furthermore, the degree of MVB across the gaps is tailored by applying uniaxial strain, which results in a large variation of dielectric function and reflectivity in the trigonal phase. At last, design strategies are provided for applications utilizing the trigonal phase.

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“…Pronounced optical or electrical contrast between amorphous and crystalline states and non-volatile properties were first employed in rewritable optical CDs, DVDs and Blu-ray disks [51], and were later exploited in electronic phase-change random access memory (PCRAM) [52][53][54]. The optical contrast of PCMs stems from a fundamental change in the bonding mechanism from covalent bonding in the amorphous phase to metavalent bonding in the crystalline phase [55][56][57][58][59].…”

Section: Introductionmentioning

confidence: 99%

Fabrication and integration of photonic devices for phase-change memory and neuromorphic computing

Zhou,

Shen,

Yang

et al. 2024

Int. J. Extrem. Manuf.

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In the past decade, there has been tremendous progress in integrating chalcogenide phase-change materials (PCMs) on the silicon photonic platform for non-volatile memory to neuromorphic in-memory computing applications. Especially, these non von Neumann computational elements and systems benefit from mass manufacturing of silicon photonic integrated circuits (PICs) on 8-inch wafers using 130-nm complementary metal-oxide semiconductor (CMOS) line. Chip manufacturing based on the deep-ultraviolet (DUV) lithography and electron-beam lithography (EBL) enable rapid prototyping of PICs, which can be integrated with high-quality PCMs based on the wafer-scale sputtering technique as a back-end-of-line (BEOL) process. In this article, we overview recent advances of waveguide integrated PCM memory cells, functional devices, and neuromorphic systems, with an emphasis on fabrication and integration processes to attain the state-of-the-art device performance. After a short overview of PCM based photonic devices, we discuss the materials properties of the functional layer as well as the progress on the light guiding layer, namely, the silicon and germanium waveguide platforms. Next, we discuss the cleanroom fabrication flow of waveguide devices integrated with thin films and nanowires, silicon waveguide and plasmonic microheaters for electrothermal switching of PCMs and mixed-mode operation. Finally, the fabrication of photonic and photonic-electronic neuromorphic computing systems is reviewed. These systems consist arrays of PCM memory elements for associative learning, matrix-vector multiplication, and pattern recognition. With large-scale integration, neuromorphic photonic computing paradigm holds the promise to outperform digital electronic accelerators by taking the advantages of ultra-high bandwidth, high speed, and energy efficient operation in running machine learning algorithms.

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Tailoring the Structural and Optical Properties of Germanium Telluride Phase-Change Materials by Indium Incorporation

Cited by 12 publications

References 100 publications

Bonding Nature and Optical Properties of As₂Te₃ Phase‐Change Material

Bonding Nature and Optical Properties of As₂Te₃ Phase‐Change Material

Metavalent Bonding in Layered Phase‐Change Memory Materials

Fabrication and integration of photonic devices for phase-change memory and neuromorphic computing

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Tailoring the Structural and Optical Properties of Germanium Telluride Phase-Change Materials by Indium Incorporation

Cited by 12 publications

References 100 publications

Bonding Nature and Optical Properties of As2Te3 Phase‐Change Material

Bonding Nature and Optical Properties of As2Te3 Phase‐Change Material

Metavalent Bonding in Layered Phase‐Change Memory Materials

Fabrication and integration of photonic devices for phase-change memory and neuromorphic computing

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Product

Resources

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Bonding Nature and Optical Properties of As₂Te₃ Phase‐Change Material

Bonding Nature and Optical Properties of As₂Te₃ Phase‐Change Material