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学者姓名：刘富荣
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摘要 ：
Traditional optical switches relying on the weak, volatile thermo-optic or electro-optic effects of Si or SiN waveguides show a high consumption and large footprint. In this paper, we reported an electric-driven phase change optical switch consisting of a Si waveguide, Ge2Sb2Te5 (GST) thin film and graphene heater suitable for large-scale integration and high-speed switching. The reversible transition between the amorphous and crystalline states was achieved by applying two different voltage pulses of 1.4 V (SET) and 4 V (RESET). The optical performance of the proposed switch showed a high extinction ration of 44-46 dB in a wide spectral range (1525-1575 nm), an effective index variation of Delta n (eff) = 0.49 and a mode loss variation of Delta alpha = 15 dB mu m(-1) at the wavelength of 1550 nm. In thermal simulations, thanks to the ultra-high thermal conductivity of graphene, the proposed switch showed that the consumption for the SET process was only 3.528 pJ with a 1.4 V pulse of 5 ns, while a 4 V pulse of 1.5 ns was needed for RESET process with a consumption of 1.05 nJ. Our work is helpful to analyze the thermal-conduction phase transition process of on-chip phase change optical switches, and the design of the low-energy-consumption switch is conducive to the integrated application of photonic chips.
关键词 ：
graphene graphene low-energy-consumption low-energy-consumption non-volatile non-volatile optical switch optical switch phase change material phase change material
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| GB/T 7714 | Li, Y. , Liu, F. R. , Han, G. et al. Design of an electric-driven nonvolatile low-energy-consumption phase change optical switch [J]. | NANOTECHNOLOGY , 2021 , 32 (40) . |
| MLA | Li, Y. et al. "Design of an electric-driven nonvolatile low-energy-consumption phase change optical switch" . | NANOTECHNOLOGY 32 . 40 (2021) . |
| APA | Li, Y. , Liu, F. R. , Han, G. , Chen, Q. Y. , Zhang, Y. Z. , Xie, X. X. et al. Design of an electric-driven nonvolatile low-energy-consumption phase change optical switch . | NANOTECHNOLOGY , 2021 , 32 (40) . |
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摘要 ：
Reversible phase-change behaviors of Ge–Sb–Te based superlattices (GST-SL) were studied by ab initio molecular dynamics (AIMD) simulations based on three models containing Ge/Sb intermixing, namely the Petrov-mix, Ferro-mix, and Kooi-mix models. The flipping behavior of Sb atoms was found in all the three GST-SL models in the melting process. Among them the Kooi-mix model exhibited the best stability, and the analyses of bond length distribution and electron localization function provided a better explanation on the phase transition of GST-SL. Finally, we proposed a fast switching model for GST-SL based on Sb flipping. © 2021 by the authors. Li-censee MDPI, Basel, Switzerland.
关键词 ：
Bond length Bond length Molecular dynamics Molecular dynamics
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| GB/T 7714 | Sun, Teng , Liu, Furong , Guo, Jicheng et al. A phase-change mechanism of gst-sl based superlattices upon sb flipping [J]. | Materials , 2021 , 14 (2) : 1-8 . |
| MLA | Sun, Teng et al. "A phase-change mechanism of gst-sl based superlattices upon sb flipping" . | Materials 14 . 2 (2021) : 1-8 . |
| APA | Sun, Teng , Liu, Furong , Guo, Jicheng , Han, Gang , Zhang, Yongzhi . A phase-change mechanism of gst-sl based superlattices upon sb flipping . | Materials , 2021 , 14 (2) , 1-8 . |
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摘要 ：
Heterostructural materials have the advantage of extreme low switching energy between states and hence are expected to be applied in photonic devices, whose optical performances are vital to explore in advance. In this paper, crystal structures of TiTe2/Sb2Te3 heterostructural films and their effects on optical properties were clarified from the aspects of in-plane strain, resonant bonding and charge redistribution by experiments and first principle simulations. Larger strain in Sb2Te3 sublayer tended to decrease reflectivity and refractive indexes, while huge resonant bonding effect was beneficial to improve the optical parameter deviations. Charge analyses showed that crystalline optical property variations were actually deriving from the electron redistribution differences especially near the heterostructural Te center dot center dot center dot Te gap, which also accounted for experimental reflectivity order. Finally, based on the resonant bond effects and surrounding electron density after stimuluses, five optical levels with identifiable optical contrasts (n and Delta R) were achieved in 1/2 model for uses. The present study sheds new light on optical properties of TiTe2/Sb2Te3 and paves the way for potential multi-state applications of heterostructure in photonic and storage devices. (C) 2021 Elsevier B.V. All rights reserved.
关键词 ：
Charge distribution Charge distribution First principle simulation First principle simulation Heterostructure Heterostructure Optical properties Optical properties
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| GB/T 7714 | Han, Gang , Liu, Furong , Zhang, Yongzhi et al. Effect of structure architecture on optical properties of TiTe2/Sb2Te3 multilayer nanofilms [J]. | JOURNAL OF ALLOYS AND COMPOUNDS , 2021 , 877 . |
| MLA | Han, Gang et al. "Effect of structure architecture on optical properties of TiTe2/Sb2Te3 multilayer nanofilms" . | JOURNAL OF ALLOYS AND COMPOUNDS 877 (2021) . |
| APA | Han, Gang , Liu, Furong , Zhang, Yongzhi , Li, Jingwen , Li, Wenqiang , Chen, Qingyuan et al. Effect of structure architecture on optical properties of TiTe2/Sb2Te3 multilayer nanofilms . | JOURNAL OF ALLOYS AND COMPOUNDS , 2021 , 877 . |
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摘要 ：
Phase-change materials (PCMs) provide an alternative avenue for modulating the adjacent layer property through interfacial effect, which sometimes is more effective than the traditional methods. Here, a systematic study of the phase-change induced control of FMR resonance field in Si/GeSbTe/FeCoB heterostructures is presented. We show that different crystalline phases induced by thermal anneal in GeSbTe/FeCoB films contribute to large shifts in resonance field of FeCoB up to 15 mT. The correlation between GeSbTe phase change and anisotropic field of FeCoB is confirmed from the GeSbTe film morphology dependent of stress. These results propose a method of phase-change induced control of FMR resonant field and ferromagnetism in PCM/ferromagnetic alloy film heterostructures by controlling interface roughness, which can be introduced in the optimization of ferromagnetic alloy film parameters and development of high functioning magnetic devices.
关键词 ：
Annealing Annealing Ferromagnetic resonance Ferromagnetic resonance Heterostructures Heterostructures Phase-change material Phase-change material
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| GB/T 7714 | Wei, Yuyi , Wang, Jiawei , Wang, Xinjun et al. Control of ferromagnetic resonance by phase change in Si/GeSbTe/ FeCoB heterostructures [J]. | JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS , 2021 , 538 . |
| MLA | Wei, Yuyi et al. "Control of ferromagnetic resonance by phase change in Si/GeSbTe/ FeCoB heterostructures" . | JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 538 (2021) . |
| APA | Wei, Yuyi , Wang, Jiawei , Wang, Xinjun , Chen, Huaihao , Yu, Chengju , He, Yifan et al. Control of ferromagnetic resonance by phase change in Si/GeSbTe/ FeCoB heterostructures . | JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS , 2021 , 538 . |
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摘要 ：
GeTe–Sb2Te3-based superlattice (GST-SL) is a new phase change film prepared with alternative GeTe and Sb2Te3 layers, known as interfacial phase-change material, showing strongly improved switching properties. However, the recent experiments showed that Ge/Sb atomic intermixing was hardly to be avoided and would influence the phase change process. In this paper, the effects of Ge/Sb atomic intermixing on the local structure and phase change mechanism were investigated by first-principles simulations. The free energy evolution with temperatures indicated that Ge/Sb intermixing is helpful for phase change. The bond analysis and local order parameter showed that no obvious structure changes happened when lower than 1200 K, and there were almost no fourfold Ge-tetrahedral structures even when quenched from 1500 K, different from the traditional GST materials. The Ge/Sb intermixing and its ratios can not only influence the structural transition, but also play a vital role on the optical properties. These findings enrich a deep understanding of Ge/Sb intermixing on GST-SL phase changes. © 2020, The Minerals, Metals & Materials Society.
关键词 ：
Germanium compounds Germanium compounds Antimony compounds Antimony compounds Free energy Free energy Optical properties Optical properties Structural properties Structural properties Phase change materials Phase change materials Mixing Mixing
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| GB/T 7714 | Han, Gang , Liu, Furong . Effects of Ge/Sb Intermixing on the Local Structures and Optical Properties of GeTe–Sb2Te3 Superlattice [C] . 2020 : 1777-1786 . |
| MLA | Han, Gang et al. "Effects of Ge/Sb Intermixing on the Local Structures and Optical Properties of GeTe–Sb2Te3 Superlattice" . (2020) : 1777-1786 . |
| APA | Han, Gang , Liu, Furong . Effects of Ge/Sb Intermixing on the Local Structures and Optical Properties of GeTe–Sb2Te3 Superlattice . (2020) : 1777-1786 . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
一种皮秒激光精确制备涡轮叶片冷却孔的装置及方法属于超快激光精密加工领域。通过控制整合了同轴CCD，激光器与六自由度平移台一体化的控制软件，将涡轮叶片冷却孔的加工过程分为两个阶段：设备属性选择与程序编写，加工工作开展与实时监控。使用皮秒固体激光器所发出的固定位置的高斯光束，六自由度平移台夹持工件进行运动，使皮秒激光在工件表面沿预先设定的路径进行辐照，激光与材料发生相互作用，从而进行加工。本发明可以实现高圆整度，低锥度的，无微裂纹及热影响区的高质量冷却孔加工。
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| GB/T 7714 | 刘富荣 , 孙腾 , 李文强 et al. 一种皮秒激光精确制备涡轮叶片冷却孔的装置及方法 : CN202010232751.1[P]. | 2020-03-28 . |
| MLA | 刘富荣 et al. "一种皮秒激光精确制备涡轮叶片冷却孔的装置及方法" : CN202010232751.1. | 2020-03-28 . |
| APA | 刘富荣 , 孙腾 , 李文强 , 韩钊 , 李玉 , 陈清远 . 一种皮秒激光精确制备涡轮叶片冷却孔的装置及方法 : CN202010232751.1. | 2020-03-28 . |
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摘要 ：
Studies have shown that the crystallization phase state of Ge2Sb2Te5 (GST) can be reversibly modulated by femtosecond (fs) laser multiple pulses, which have excellent applications in reconfigurable multi-level operation fields. In this study, the temporal-spatial crystalline evolution dynamics of amorphous GST film is investigated during two fs laser pulses excitation through a pump-probe shadowgraph imaging technique. A quasi-amorphous phase state, which is different from that in the initial as-deposited amorphous GST, is emerged through the first fs laser pulse excitation with a pulse energy lower than crystallization threshold. The experimental results reveal that a crystallization enhancement effect can be induced through the second pulse excitation based on this quasi-amorphous surface structure. The stimulative cluster generated in the quasi-amorphous reduces the amorphous-to-crystalline phase transition threshold for the second fs laser pulse irradiation. The spatially-resolved phase-transition threshold extension effect in a horizontal direction is proposed with the increasing pulse number to summarize the mechanism of the crystallization enhancement effect. The specific-grain-appearance (coarse grains and fine grains representing different phase transition approach) distributed area induced by single and double fs laser pulses irradiation are experimentally demonstrated corresponding to threshold extension theory.
关键词 ：
multiple pulse femtosecond laser multiple pulse femtosecond laser phase transition evolution phase transition evolution quasi-amorphous phase state quasi-amorphous phase state temporal-spatial-resolved dynamics temporal-spatial-resolved dynamics
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| GB/T 7714 | Han, Z. H. , Han, W. N. , Liu, F. R. et al. Ultrafast temporal-spatial dynamics of amorphous-to-crystalline phase transition in Ge2Sb2Te5 thin film triggered by multiple femtosecond laser pulses irradiation [J]. | NANOTECHNOLOGY , 2020 , 31 (11) . |
| MLA | Han, Z. H. et al. "Ultrafast temporal-spatial dynamics of amorphous-to-crystalline phase transition in Ge2Sb2Te5 thin film triggered by multiple femtosecond laser pulses irradiation" . | NANOTECHNOLOGY 31 . 11 (2020) . |
| APA | Han, Z. H. , Han, W. N. , Liu, F. R. , Han, Z. , Yuan, Y. P. , Cheng, Z. C. . Ultrafast temporal-spatial dynamics of amorphous-to-crystalline phase transition in Ge2Sb2Te5 thin film triggered by multiple femtosecond laser pulses irradiation . | NANOTECHNOLOGY , 2020 , 31 (11) . |
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摘要 ：
In this paper, the effect of laser wavelength on the thermal behavior of amorphous Ge2Sb2Te5 (a-GST) films induced by a frequency-tripled picosecond laser was carried out using 3D surface profile, SEM, TEM and Raman measurement. Melting thresholds of a-GST films with different wavelengths of 355 nm (3.5 mJ/cm(2)), 532 nm (28 mJ/cm(2)) and 1064 nm (22.3 mJ/cm(2)) were obtained, respectively. It showed that with the increase of wavelength from 355 to 532 and 1064 nm, pit morphologies and crystallization degree didn't follow a monotonous relation, which were mainly affected by melting threshold, optical penetration depth as well as photon energy. TEM images demonstrated that 532 nm laser-treated samples got more complete crystallization than those 355 nm laser treated. Besides, for the remarkable discrepancy in optical penetration depth among the three laser wavelengths, the crystallization process of a-GST at 355 and 532 nm wavelengths performed with a surficial heating mode, different from that at 1064 nm wavelength with a body heating mode. The present study paves the way to achieve the big-data storage using different wavelengths.
关键词 ：
Frequency-tripled picosecond laser Frequency-tripled picosecond laser Ge2Sb2Te5 Ge2Sb2Te5 Phase-change material Phase-change material Phase transformation Phase transformation
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| GB/T 7714 | Zhang, Y. Z. , Liu, F. R. , Wang, Z. M. et al. Effect of laser wavelength on the thermal behavior of amorphous GST films irradiated by a single frequency-tripled picosecond laser [J]. | OPTICS AND LASER TECHNOLOGY , 2020 , 121 . |
| MLA | Zhang, Y. Z. et al. "Effect of laser wavelength on the thermal behavior of amorphous GST films irradiated by a single frequency-tripled picosecond laser" . | OPTICS AND LASER TECHNOLOGY 121 (2020) . |
| APA | Zhang, Y. Z. , Liu, F. R. , Wang, Z. M. , Guo, J. C. , Liu, W. Q. , Sun, N. X. . Effect of laser wavelength on the thermal behavior of amorphous GST films irradiated by a single frequency-tripled picosecond laser . | OPTICS AND LASER TECHNOLOGY , 2020 , 121 . |
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摘要 ：
Achieving multi-level properties of chalcogenide phase change materials is highly desirable for high-density data storage, photonic switches and neuromorphic computing etc. In this paper, we report a multi-level implement scheme via a two-step picosecond laser irradiation strategy on the basis of time/space modulations of microstructure and property of Ge2Sb2Te5 (GST) phase change thin films. Unlike the common grey-scale method by multiple laser irradiations at a fixed position, multi-levels of optical properties were obtained by two-step overlapping laser irradiations together with such varied parameters as the overlapping ratio, input energy and two-pulse duration. Variations of the microstructure and optical property were characterized by transmission electron microscope (TEM) and microarea reflectance testing. It showed that the overlapping ratio was an important factor to adjust microstructure patterns and optical properties. With the increase of the overlapping ratio, the optical reflectivity presented a trend of increasing first and then decreasing, mainly because of the effects of the size and distribution of grains from the second laser irradiations. Based on the scheme proposed, a 10-level optical reflectivity could be obtained. The fundamental research performed in this study is of importance to give guideline for high-density storage or big-data processing with phase change materials in the future.
关键词 ：
chalcogenide phase change materials chalcogenide phase change materials microstructure microstructure multi-level optical reflectivity multi-level optical reflectivity two-step laser irradiation scheme two-step laser irradiation scheme
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| GB/T 7714 | Zhang, Y. Z. , Liu, F. R. , Han, Z. et al. A multi-level optical storage scheme via two-step picosecond laser irradiations: time/space modulations of microstructure and its optical property [J]. | SEMICONDUCTOR SCIENCE AND TECHNOLOGY , 2020 , 35 (3) . |
| MLA | Zhang, Y. Z. et al. "A multi-level optical storage scheme via two-step picosecond laser irradiations: time/space modulations of microstructure and its optical property" . | SEMICONDUCTOR SCIENCE AND TECHNOLOGY 35 . 3 (2020) . |
| APA | Zhang, Y. Z. , Liu, F. R. , Han, Z. , Li, W. Q. , Huang, Y. , Sun, N. X. . A multi-level optical storage scheme via two-step picosecond laser irradiations: time/space modulations of microstructure and its optical property . | SEMICONDUCTOR SCIENCE AND TECHNOLOGY , 2020 , 35 (3) . |
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摘要 ：
Ge/Sb atomic intermixing in interfacial cationic layers is a common phenomenon for GeTe-Sb2Te3 superlattice (GST-SL) used in memory devices. In this paper, we explored the effect of Ge/Sb intermixing on the phase change behavior of GST-SL upon the heating-quenching procedure. Four interfacial intermixing models of Kooi, Ferro, Petrov and inverted Petrov with different Ge/Sb intermixing ratios (25/75, 50/50 and 75/25) were developed based on the ab initio molecular dynamics. The structural evolution indicated that the Ge/Sb interfacial intermixing could facilitate the structure changes especially for 50/50 Ge/Sb intermixed models. When quenching from 1500 K, more 4-fold Ge-centered octahedrons were produced than tetrahedrons, and the electron localization function further proved that the distorted of Ge(Sb)-centered 6-fold octahedrons were caused by the asymmetrical interactions of Ge-Ge/Sb and Ge-Te. A relatively large Te p orbital contribution in coexisted Ge/Te layer led to a narrower bandgap. In addition, different Ge/Sb atom intermixed ratio which affected the electronic local structure, led to the discrepancy in the initial atom movement of Sb or Ge movement near the gap. The present studies enrich the understanding of Ge/Sb interfacial atomic intermixing effects in GST-SL structural changes.
关键词 ：
ab initio molecular dynamics ab initio molecular dynamics interfacial intermixing ratio interfacial intermixing ratio local structure local structure superlattice superlattice
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| GB/T 7714 | Han, Gang , Liu, Furong , Li, Wenqiang et al. Local structure and phase change behavior in interfacial intermixing GeTe-Sb2Te3 superlattices [J]. | JOURNAL OF PHYSICS-CONDENSED MATTER , 2020 , 32 (25) . |
| MLA | Han, Gang et al. "Local structure and phase change behavior in interfacial intermixing GeTe-Sb2Te3 superlattices" . | JOURNAL OF PHYSICS-CONDENSED MATTER 32 . 25 (2020) . |
| APA | Han, Gang , Liu, Furong , Li, Wenqiang , Huang, Yin , Sun, Nianxiang , Ye, Feng . Local structure and phase change behavior in interfacial intermixing GeTe-Sb2Te3 superlattices . | JOURNAL OF PHYSICS-CONDENSED MATTER , 2020 , 32 (25) . |
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