@article{685a8972fd5a4ea3a19e79b543e15f6c,
title = "Exploring “No Man's Land”—Arrhenius Crystallization of Thin-Film Phase Change Material at 1 000 000 K s−1 via Nanocalorimetry",
abstract = "Non-volatile phase-change memory (PCM) devices are based on phase-change materials such as Ge2Sb2Te5(GST). PCM requires critically high crystallization growth velocity (CGV) for nanosecond switching speeds, which makes its material-level kinetics investigation inaccessible for most characterization methods and remains ambiguous. In this work, nanocalorimetry enters this “no-man's land” with scanning rate up to 1 000 000 K s−1 (fastest heating rate among all reported calorimetric studies on GST) and smaller sample-size (10–40 nm thick) typical of PCM devices. Viscosity of supercooled liquid GST (inferred from the crystallization kinetic) exhibits Arrhenius behavior up to 290 °C, indicating its low fragility nature and thus a fragile-to-strong crossover at ≈410 °C. Thin-film GST crystallization is found to be a single-step Arrhenius process dominated by growth of interfacial nuclei with activation energy of 2.36 ± 0.14 eV. Calculated CGV is consistent with that of actual PCM cells. This addresses a 10-year-debate originated from the unexpected non-Arrhenius kinetics measured by commercialized chip-based calorimetry, which reports CGV 103−105 higher than those measured using PCM cells. Negligible thermal lag (<1.5 K) and no delamination is observed in this work. Melting, solidification, and specific heat of GST are also measured and agree with conventional calorimetry of bulk samples.",
keywords = "Arrhenius behavior, crystallization growth velocity, nanocalorimetry, phase change materials, viscosity",
author = "Jie Zhao and Jian Hui and Zichao Ye and Tianxing Lai and Efremov, {Mikhail Y.} and Hong Wang and Allen, {Leslie H.}",
note = "Funding Information: J.Z. and J.H. contributed equally to this work. This work was supported by NSF-DMR-1409953 and NSF-DMR-1809573. Materials characterization and thin film deposition (aluminum and indium) were carried out in part in the Frederick Seitz Materials Research Laboratory (MRL), University of Illinois Urbana-Champaign. Thin film deposition of GST was conducted in State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Shanghai, China. NanoDSC sensors were fabricated at the Cornell Nanoscale Facility, a member of the National Nanotechnology Infrastructure Network (NNIN). The authors would thank for the support from the “Shanghai Jiao Tong University Outstanding Doctoral Students Overseas Visiting Scholarship Program” and the financial support from Shanghai Jiao Tong University for Jian Hui as a visiting scholar. The authors are also grateful for MRL staffs who provided valuable advices on designing a TEM holder that is compatible for NanoDSC sensors. The authors thank Timothy Spila for assistance in RBS analysis. Funding Information: J.Z. and J.H. contributed equally to this work. This work was supported by NSF‐DMR‐1409953 and NSF‐DMR‐1809573. Materials characterization and thin film deposition (aluminum and indium) were carried out in part in the Frederick Seitz Materials Research Laboratory (MRL), University of Illinois Urbana‐Champaign. Thin film deposition of GST was conducted in State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro‐system and Information Technology, Shanghai, China. NanoDSC sensors were fabricated at the Cornell Nanoscale Facility, a member of the National Nanotechnology Infrastructure Network (NNIN). The authors would thank for the support from the “Shanghai Jiao Tong University Outstanding Doctoral Students Overseas Visiting Scholarship Program” and the financial support from Shanghai Jiao Tong University for Jian Hui as a visiting scholar. The authors are also grateful for MRL staffs who provided valuable advices on designing a TEM holder that is compatible for NanoDSC sensors. The authors thank Timothy Spila for assistance in RBS analysis. Publisher Copyright: {\textcopyright} 2022 The Authors. Advanced Materials Interfaces published by Wiley-VCH GmbH.",
year = "2022",
month = aug,
day = "11",
doi = "10.1002/admi.202200429",
language = "English (US)",
volume = "9",
journal = "Advanced Materials Interfaces",
issn = "2196-7350",
publisher = "John Wiley & Sons, Ltd.",
number = "23",
}