Phase-change mechanism and role of each element in Ag-In-Sb-Te: Chemical bond evolution

Kim, Dasol; Jung, Taek Sun; Park, Hanjin; Yang, Wonseok; Han, Jung Suk; Hwang, Sung Kwan; Sim, Kyung Ik; Kwon, Young–Kyun; Kim, Jae-Hoon; Cho, Mann‐Ho

doi:10.1016/j.apsusc.2020.148838

Cited by 8 publications

(6 citation statements)

References 54 publications

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“…Based on the above discussions, we can summarize the reaction process of AIST in the Cl-based plasma: At the very beginning, according to the results of XRD, the developed AIST consists of Ag–In–Te and Sb crystals, which constitute the tetragonal structure . Then, from the results of Raman and XPS spectra, the chemical bonds of AIST change from Ag–In–Te and Sb (Sb–O) to In–Cl, Sb–Cl (O), and Te–Cl heteropolar bonds on the surface.…”

Section: Resultsmentioning

confidence: 99%

“…As we have studied before, , the as-deposited AIST can be crystallized under laser irradiation. Strong diffraction peaks can be found in the laser-exposed AIST resist, which corresponds to the mixture of Sb and Ag–In–Te crystallites (including AgIn 3 Te 5 and AgInTe 2 ). After developing in the alkaline solution, the intensity of some peaks decreases.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Nanoscale-Patterned Cr Films by Selective Etching Using a Heat-Mode Resist: Implications for X-ray Beam Splitter

Chen

Liu

Wei

et al. 2021

ACS Appl. Nano Mater.

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Nanoscale-patterned chromium (Cr) metal structures are widely used in a large variety of semiconductor processing fields. These structures are usually fabricated via the direct etching method. Owing to the drawbacks of traditional lithography techniques (such as electron beam, ion beam, and scanning probe lithography), it is still a high-cost and complex work to accomplish nanoscale structure fabrication. In this paper, through laser heat-mode lithography, a chalcogenide AgInSbTe (AIST) film is chosen as the dry-etching resist to fabricate a series of arbitrary micro/nanostructures on the Cr film. The etching mechanism from the AIST resist to the Cr mask under the Cl2/O2-based gases has been elucidated through energy-dispersive X-ray spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. A grating pattern with a minimum pitch of 300 nm has been achieved on the Cr mask, and successfully transferred onto a diamond substrate as an X-ray beam splitter. This work provides an effective method for nanoscale structure fabrication and clarifies the antietching mechanisms of AIST resist films under Cl-based plasma etching.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Nanoscale-Patterned Cr Films by Selective Etching Using a Heat-Mode Resist: Implications for X-ray Beam Splitter

Chen

Liu

Wei

et al. 2021

ACS Appl. Nano Mater.

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“…While drastic decreases in the electrical resistance during annealing are typically observed in GST and AIST, those are not found in Sb 2 Te 3 . The drastic changes of GST and AIST have been successfully explained by the transition of the local environment of certain elements in early reports such as the umbrella flip, bond-interchange, and dam-gate models. ,, On the other hand, the gradual change of Sb 2 Te 3 without a drastic decrease can be explained by the characteristic behavior of site-switching of inherent vacancies with diverged magnitude of the energy barrier. The lattice parameters along the c -axis direction also smoothly contract, as shown in Figure f.…”

Section: Resultsmentioning

confidence: 99%

“…Herein, based on the direct observation of the evolution of the chemical states of vacancies, the kinetic behaviors of vacancies were studied in metastable and stable Sb 2 Te 3 , as a prototype of chalcogenide PCMs. The site-switching of vacancies gradually occurs with diverged energy barriers through gliding along atomic planes in which the kinetics of the vacancies can be considered as a second-order transition. , The behavior is extended to Sb 2 Te 3 /GeTe superlattices in which the site-switching of vacancies is suppressed or encouraged depending on the types of interfacial structure, where the combination of those interfaces classifies the stability of the phases as metastable and stable states. Notably, conversion in bond types between the metavalent bond and covalent bond is corroborated in metastable superlattices with the transition of local environments of Ge. − We believe that this study provides a perspective of the kinetics in the vacancies, where the metastable and stable states are expected to be applicable to other functional materials with vacancies.…”

mentioning

confidence: 99%

Conversion between Metavalent and Covalent Bond in Metastable Superlattices Composed of 2D and 3D Sublayers

Kim

et al. 2022

ACS Nano

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Reversible conversion over multimillion times in bond types between metavalent and covalent bonds becomes one of the most promising bases for universal memory. As the conversions have been found in metastable states, an extended category of crystal structures from stable states via redistribution of vacancies, research on kinetic behavior of the vacancies is highly in demand. However, it remains lacking due to difficulties with experimental analysis. Herein, the direct observation of the evolution of chemical states of vacancies clarifies the behavior by combining analysis on charge density distribution, electrical conductivity, and crystal structures. Site-switching of vacancies of Sb 2 Te 3 gradually occurs with diverged energy barriers owing to their own activation code: the accumulation of vacancies triggers spontaneous gliding along atomic planes to relieve electrostatic repulsion. Studies on the behavior can be further applied to multiphase superlattices composed of Sb 2 Te 3 (2D) and GeTe (3D) sublayers, which represent superior memory performances, but their operating mechanisms were still under debate due to their complexity. The site-switching is favorable (suppressed) when Te−Te bonds are formed as physisorption (chemisorption) over the interface between Sb 2 Te 3 (2D) and GeTe (3D) sublayers driven by configurational entropic gain (electrostatic enthalpic loss). Depending on the type of interfaces between sublayers, phases of the superlattices are classified into metastable and stable states, where the conversion could only be achieved in the metastable state. From this comprehensive understanding on the operating mechanism via kinetic behaviors of vacancies and the metastability, further studies toward vacancy engineering are expected in versatile materials.

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Direct Laser Writing Dry Lithography of High‐Resolution Micro‐/Nanostructures in AgSb₄Te Thin Film for Tunable Perfect Absorber

Chen,

Yao,

Wei

et al. 2023

Physica Rapid Research Ltrs

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Direct laser writing is promising for fabrication of functional structures due to its high speed, low cost, and facile operation. However, high resolution is difficult to be implemented due to wet development‐induced structural collapse. Ag‐doped Sb4Te thin film is proposed for high‐resolution direct laser writing dry lithography. The crystalline structures and binding environment of AgSb4Te thin films are investigated. The dry lithographic characteristics suggest that the developing selectivity of exposed to as‐deposited film is as high as 17 under CHF3/O2 gas and the minimum linewidth of patterns can reach 80 nm via adjusting grating period. Developing selectivity mechanism is ascribed to exposure induced phase separation along with generation of Sb component and Ag7Te4 phases. The Sb component can be readily etched due to the lack of Ag atom protection and then etching of residual Ag7Te4 phase is further promoted while the uniformly distributed Ag atoms in as‐deposited film restrain its etching. In addition, nanohole array is fabricated onto AgSb4Te thin films and tunable absorbance can be realized by adjusting pattern period and phase‐change process. This work may provide a useful guide for the investigation of direct laser writing lithography mechanism and functional device fabrication.

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Phase-change mechanism and role of each element in Ag-In-Sb-Te: Chemical bond evolution

Cited by 8 publications

References 54 publications

Nanoscale-Patterned Cr Films by Selective Etching Using a Heat-Mode Resist: Implications for X-ray Beam Splitter

Nanoscale-Patterned Cr Films by Selective Etching Using a Heat-Mode Resist: Implications for X-ray Beam Splitter

Conversion between Metavalent and Covalent Bond in Metastable Superlattices Composed of 2D and 3D Sublayers

Direct Laser Writing Dry Lithography of High‐Resolution Micro‐/Nanostructures in AgSb₄Te Thin Film for Tunable Perfect Absorber

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Phase-change mechanism and role of each element in Ag-In-Sb-Te: Chemical bond evolution

Cited by 8 publications

References 54 publications

Nanoscale-Patterned Cr Films by Selective Etching Using a Heat-Mode Resist: Implications for X-ray Beam Splitter

Nanoscale-Patterned Cr Films by Selective Etching Using a Heat-Mode Resist: Implications for X-ray Beam Splitter

Conversion between Metavalent and Covalent Bond in Metastable Superlattices Composed of 2D and 3D Sublayers

Direct Laser Writing Dry Lithography of High‐Resolution Micro‐/Nanostructures in AgSb4Te Thin Film for Tunable Perfect Absorber

Contact Info

Product

Resources

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Direct Laser Writing Dry Lithography of High‐Resolution Micro‐/Nanostructures in AgSb₄Te Thin Film for Tunable Perfect Absorber