Article
Chemistry, Multidisciplinary
Heng Zhang, Daniel T. Yimam, Sytze de Graaf, Jamo Momand, Paul A. Vermeulen, Yingfen Wei, Beatriz Noheda, Bart J. Kooi
Summary: Strain engineering has attracted significant interest as a method to control functional properties. Recent research on heterostructures based on Bi2Te3, Sb2Te3, and GeTe has shown potential for a different type of strain engineering due to long-range mutual straining. The study reveals a fast relaxation process in the mica/Bi2Te3 system and long-range strain retention in GeTe and Sb2Te3 grown on or with Bi2Te3. Immediate strain relaxation by plastic deformation was observed, ruling out an elastic model for strain relaxation.
Review
Engineering, Electrical & Electronic
Naor Madar, Yatir Sadia, Yaniv Gelbstein
Summary: This research focuses on the thermoelectric potential of (GeTe)(1-x)(Bi2Te3)(x) alloys with the aim of reducing reliance on fossil fuels. By introducing Bi2Te3 as a doping agent, the high inherent hole concentration of GeTe can be compensated, leading to optimal thermoelectric properties. The particle size and pressing direction have an influence on the crystal structure and preferred orientation of the alloy. A maximum thermoelectric figure of merit (ZT) of approximately 2 was achieved at a particle size of smaller than 1 μm, one of the highest reported for any p-type thermoelectric alloy.
ACS APPLIED ELECTRONIC MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Hanxia Zhang, Xiaoyu Yang, Xinyue Zhang, Pengfei Nan, Binghui Ge, Zhiwei Chen, Yanzhong Pei
Summary: Anisotropy in lattice thermal conductivity (KL) of crystals is commonly caused by the anisotropic crystal structure. However, this anisotropy can be easily eliminated in polycrystalline materials due to the random orientation of grains. In this study, a significant enhancement in KL-anisotropy is achieved in polycrystalline (GeTe)m(Bi2Te3)n through ordered 1D/2D defects induced by high-concentration vacancies. The resulting KL-anisotropy is approximately twice as large as that of GeTe. This research provides an effective strategy for manipulating the anisotropy of heat transport through a structural control of ordered high-dimension defects, which can be well described by a phonon-defect scattering model.
MATERIALS TODAY PHYSICS
(2023)
Article
Chemistry, Physical
Li Chen, Lin Wang, Kai Jiang, Jinzhong Zhang, Yawei Li, Liyan Shang, Liangqing Zhu, Shijing Gong, Zhigao Hu
Summary: Ultrafast photoexcitation can be used as a probe to study photoinduced phase transition. The study conducted real-time simulations and found that short-wavelength laser excitation leads to carrier excitation and repopulation, while long-wavelength laser excitation favors the excitation of lone pair electrons. Photodoping and coherent forces play a crucial role in activating phase reversal and suppressing Peierls distortion. These findings have significant implications for nonequilibrium phase engineering using phase-change materials.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Nanoscience & Nanotechnology
Jianqiang Zhang, Ping Wei, Huiqiang Zhang, Longzhou Li, Wanting Zhu, Xiaolei Nie, Wenyu Zhao, Qingjie Zhang
Summary: Stable Ni/Bi2Te3 joints were established by arc spraying the Ni barrier layer on Bi2Te3-based alloys. Compared with traditional joints, the arc-sprayed joints showed lower contact resistivity and higher bonding strength. After aging at high temperature, the arc-sprayed joints exhibited better thermal shock tolerance with stable bonding strength and contact resistivity. This work provides an effective strategy for establishing stable joints with improved thermal stability in Bi2Te3-based thermoelectric devices.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Chemistry, Physical
Guillaume Roland, Alain Portavoce, Maxime Bertoglio, Marion Descoins, Jacopo Remondina, Didier Dutartre, Frederic Lorut, Magali Putero
Summary: The growth of GeTe compound is crucial for technological applications and fundamental understanding. In this study, GeTe crystallization kinetics was compared with Ge/Te reactive diffusion kinetics using in situ X-ray diffraction measurements and in situ transmission electron microscopy. The results showed that GeTe growth follows a three-dimensional pattern and can be modeled using the Johnson-Mehl-Avrami-Kolmogorov model. Interestingly, GeTe exhibits unusually low nucleation reaction kinetics compared to atomic transport kinetics, which is different from other germanides.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Chemistry, Physical
Seong Won Cho, Young Woong Lee, Sang Heon Kim, Seungwu Han, Inho Kim, Jong-Keuk Park, Joon Young Kwak, Jaewook Kim, YeonJoo Jeong, Gyu Weon Hwang, Kyeong Seok Lee, Seongsik Park, Suyoun Lee
Summary: This study investigates the superlattices composed of Bi2Te3 and GeTe, finding that they have reduced carrier density and larger Rashba constant, which can enhance the ferroelectricity and spin-orbit coupling effect in GeTe material.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Chemistry, Multidisciplinary
Libo Miao, Yegang Lu, Yu Zhang, Wei Sun, Ziyang Hu
Summary: In this study, the influence of thickness reduction on the phase-change behavior of GeTe films was investigated by studying both uncovered and Si3N4-covered GeTe films. The results showed that with decreasing film thickness, the resistance, optical band gap, and thermal stability of GeTe films were improved. The coverage of Si3N4 further enhanced the thermal stability and resistance drift of GeTe.
CRYSTAL GROWTH & DESIGN
(2022)
Article
Crystallography
T. M. Alakbarova, Hans-Juergen Meyer, E. N. Orujlu, I. R. Amiraslanov, M. B. Babanly
Summary: The GeTe-GeBi2Te4 part of the GeTe-Bi2Te3 quasi-binary system was re-examined, confirming the existence of 4 ternary compounds. Compounds Ge2Bi2Te5 and GeBi2Te4 were formed by peritectic reactions, while Ge3Bi2Te6 and Ge4Bi2Te7 decomposed by solid-phase reactions. Furthermore, a morphotropic phase transition from rhombohedral to cubic occurred between 9 and 10 mol% Bi2Te3 compositions. Crystallographic parameters were determined by the Rietveld method and a comparative analysis with literature data was performed.
Article
Chemistry, Multidisciplinary
Shuo Li, Yu-Jie Sun, Zhao-Xu Wang, Cheng-Gang Jin, Ming-Jie Yin, Quan-Fu An
Summary: In this study, a solvent-controlled crystallization strategy was employed to achieve in-situ crystallization of MOF nanocrystals in the polymer matrix, resulting in the construction of defect-free CO2 transportation channels. The fabricated mixed matrix membranes exhibit approximately fourfold enhancement in CO2 permeability, i.e., 2490 Barrer, with a CO2/N-2 selectivity of 37, along with outstanding antiplasticization merit and long-term stability, enabling the large-scale manufacture of high-performance membranes for gas separation.
Article
Materials Science, Multidisciplinary
Julian Pries, Yuan Yu, Peter Kerres, Maria Haeser, Simon Steinberg, Fabian Gladisch, Shuai Wei, Pierre Lucas, Matthias Wuttig
Summary: A new approach is proposed to estimate the glass transition temperature T-g of GeTe by progressively crystallizing Ge15Te85. Selective crystallization of pure tellurium during sub-T-g annealing leads to a gradual change in the composition of the amorphous surrounding toward that of GeTe, resulting in a new endotherm whose onset temperature gradually approaches the T-g of GeTe.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2021)
Article
Materials Science, Composites
Jan Sher Khan, Rizwan Akram, Mozaffar Hussain, Saima Rafique, Farrukh Bashir Kayani, Anis Ur Rehman
Summary: Composite fibers of bismuth telluride with polyaniline and polyvinylpyrrolidone were synthesized via electrospinning. The morphology and surface morphology of the fibers were studied using scanning electron microscopy. The X-ray diffraction and Fourier transform infrared spectroscopy confirmed the increase in crystalline phase and revealed the influence of functional groups. The thermogravimetric analysis and diffuse reflectance spectroscopy showed the thermal stability and decreased bandgap of the composite fibers.
POLYMER COMPOSITES
(2023)
Article
Polymer Science
Nicholas F. Mendez, Deboleena Dhara, Qingteng Zhang, Suresh Narayanan, Linda S. Schadler, Alejandro J. J. Muller, Sanat K. Kumar
Summary: X-ray photon correlation spectroscopy measurements were used to analyze the dynamics of bare and bimodal grafted silica nanoparticles mixed with PEO melts. The results showed diffusive behavior of the nanoparticles in dilute polymer nanocomposite samples, taking into account the adsorbed PEO polymer layer. The dynamics of grafted nanoparticles were found to be influenced by morphology and grafting parameters at larger scales.
Article
Chemistry, Multidisciplinary
Tong Xing, Chenxi Zhu, Qingfeng Song, Hui Huang, Jie Xiao, Dudi Ren, Moji Shi, Pengfei Qiu, Xun Shi, Fangfang Xu, Lidong Chen
Summary: This study achieved a superhigh thermoelectric figure-of-merit (zT) of approximately 2.5 at 700 K by regulating the (Mg, Bi) co-doping in GeTe. The research found that (Mg, Bi) co-doping can effectively reduce the lattice thermal conductivity of GeTe compounds and introduce additional electrons to optimize carrier concentration, thereby improving the overall thermoelectric performance of the material.
ADVANCED MATERIALS
(2021)
Article
Materials Science, Multidisciplinary
M. Cobelli, D. Dragoni, S. Caravati, M. Bernasconi
Summary: Ge2Sb2Te5 and GeTe compounds are of interest for phase change memories, where a rapid crystal-to-amorphous transition is achieved through Joule heating. Metal-semiconductor transition temperature TM-SC is estimated using density functional simulations, with the importance of van der Waals interactions highlighted. Including vdW interactions gives improved estimates closer to the melting temperature T-m, and suggests a continuous structural transformation associated with the metal-semiconductor transition.
PHYSICAL REVIEW MATERIALS
(2021)
Article
Physics, Multidisciplinary
Gwanmu Lee, Junhong Na, Dongseok Suh
JOURNAL OF THE KOREAN PHYSICAL SOCIETY
(2020)
Article
Multidisciplinary Sciences
Sung Min Park, Bo Wang, Tula Paudel, Se Young Park, Saikat Das, Jeong Rae Kim, Eun Kyo Ko, Han Gyeol Lee, Nahee Park, Lingling Tao, Dongseok Suh, Evgeny Y. Tsymbal, Long-Qing Chen, Tae Won Noh, Daesu Lee
NATURE COMMUNICATIONS
(2020)
Article
Materials Science, Multidisciplinary
Jeong-Gyun Kim, Dongseok Suh, Haeyong Kang
Summary: Twist-spun carbon nanotube (CNT) yarns consist of numerous CNTs and their bundles which have entangled and twisted structures. While individual CNTs have high mechanical strength, CNT yarns are flexible and can change shape, making them suitable for wearable device design. By adjusting the geometrical structure, a wide range of Young's modulus can be achieved, allowing for various applications requiring different stresses.
CURRENT APPLIED PHYSICS
(2021)
Article
Materials Science, Multidisciplinary
Tuan Khanh Chau, Dongseok Suh, Haeyong Kang
Summary: A monolayer graphene transistor device in the shape of a Hall-bar structure was fabricated, exhibiting standard integer quantum Hall effect with anomalies in the electron region corresponding to small filling factors. The presence of possible electron traps causing localized states near the Dirac point was investigated, with excess electrons needed to fill these trap levels to explain the inequality between electron and hole fillings. The relationships between quantum Hall plateaus, Landau levels, and filling factors were carefully analyzed to reveal details of localized states in the graphene device.
CURRENT APPLIED PHYSICS
(2021)
Article
Materials Science, Multidisciplinary
Nahee Park, Tuan Khanh Chau, Sang-Goo Lee, Haeyong Kang, Dongseok Suh
Summary: The study found that ferroelectric polarization has a significant modulation effect on the charge carriers in MoTe2, resulting in an imbalance between electron and hole carriers due to hole-trap effects at the interfaces, which leads to asymmetric controllability of charge conduction in MoTe2.
CURRENT APPLIED PHYSICS
(2021)
Article
Materials Science, Multidisciplinary
Geunchang Choi, Tuan Khanh Chau, Sung Ju Hong, Dasom Kim, Sung Hyuk Kim, Dai-Sik Kim, Dongseok Suh, Young-Mi Bahk, Mun Seok Jeong
Summary: The study demonstrates a method for achieving negative-type high on/off ratio and ultrafast terahertz modulation using graphene/metal nanoslot antennas. The graphene covering and optical pumping result in resonant modulation of terahertz transmission. Rapid carrier relaxation induced by a strong terahertz field contributes to faster modulation of transient terahertz transmission.
ADVANCED OPTICAL MATERIALS
(2021)
Article
Chemistry, Physical
Jae Myeong Lee, Sungwoo Chun, Wonkyeong Son, Dongseok Suh, Shi Hyeong Kim, Hyun Kim, Dongyum Lee, Younghoon Kim, Young-Kwan Kim, Sang Kyoo Lim, Changsoon Choi
Summary: In this study, a DNA-inspired supercoil battery was developed by supercoiling a fiber electrode, which exhibited excellent stretchability and high linear capacity compared to other types of stretchable fiber batteries, providing a promising solution for wearable energy storage applications.
Article
Chemistry, Physical
Duc Anh Nguyen, Dae Young Park, Juchan Lee, Ngoc Thanh Duong, Chulho Park, Duc Hieu Nguyen, Thi Suong Le, Dongseok Suh, Heejun Yang, Mun Seok Jeong
Summary: Laser-driven synthesis of PtTe2 from Pt-deposited 2D tellurium (Te) optimized the interface of 2D Te optoelectronic device, transforming the electrical properties from p-type semiconductor to metallic. This leads to greatly enhanced carrier mobility and photoresponsivity in the 2D Te devices, with high responsivity and detectivity achieved.
Article
Chemistry, Multidisciplinary
Wonkyeong Son, Sungwoo Chun, Jae Myeong Lee, Gichan Jeon, Hyeon Jun Sim, Hyeon Woo Kim, Sung Beom Cho, Dongyun Lee, Junyoung Park, Joonhyeon Jeon, Dongseok Suh, Changsoon Choi
Summary: In this study, a twist-stable and hydrophilic coiled carbon nanotube (CNT) yarn was prepared by the easy electrochemical oxidation (ECO) method. The resulting yarns showed increased density and capacitance, and were fabricated into stretchable supercapacitors.
Article
Physics, Multidisciplinary
Gwanmu Lee, Sehwan Park, Dongseok Suh, Sung Ju Hong, Jaewan Choi, Hyunjin Ji
Summary: By measuring and analyzing the thermal characteristics of CVD-grown monolayer MoS2 field-effect transistors, we found that Joule heating has a significant impact on their performance. The maximum temperature of the channel increases due to the asymmetry of the charge distribution when the transistor operates in the saturation mode. The relationship between the maximum temperature and input power density initially shows linearity but becomes more nonlinear as the input power increases, with a more pronounced nonlinearity under negative drain-source bias conditions. These results demonstrate the importance of charge distribution and total input power in thermal analysis studies based on 2D materials.
JOURNAL OF THE KOREAN PHYSICAL SOCIETY
(2022)
Article
Chemistry, Multidisciplinary
Wonkyeong Son, Jae Myeong Lee, Shi Hyeong Kim, Hyeon Woo Kim, Sung Beom Cho, Dongseok Suh, Sungwoo Chun, Changsoon Choi
Summary: A rapidly recoverable high-power hydro-actuator has been achieved by designing biomimetic carbon nanotube yarns, which demonstrate structural stability and high contractile work, recovery speed, actuation frequency, and power density.
Article
Materials Science, Multidisciplinary
Tuan Khanh Chau, Sung Ju Hong, Haeyong Kang, Dongseok Suh
Summary: The recent discovery of a two-dimensional van der Waals magnet has opened up new possibilities for understanding two-dimensional magnetic systems. By coupling monolayer graphene with the two-dimensional ferromagnet CGT, we are able to electrically monitor the magnetic phase transition of the CGT layer.
NPJ QUANTUM MATERIALS
(2022)
Article
Chemistry, Physical
Tuan Khanh Chau, Dongseok Suh, Haeyong Kang
Summary: This study investigates the influence of individual grain boundaries (GBs) on the quantum Hall effect (QHE) in monolayer chemical vapor deposition (CVD) graphene. It finds that the scattering of GBs only affects the longitudinal resistance (R-xx) in the low carrier concentration region, while the standard QHE of monolayer graphene can be observed regardless of the stitching angle of the GB. Additionally, a controlled device with an added metal bar is introduced, showing that only R-xx is affected by nonzero resistance, while the Hall resistance (R-xy) exhibits well-quantized plateaus in the QH state.
Article
Chemistry, Multidisciplinary
Hyo-Bae Kim, Moonyoung Jung, Youkyoung Oh, Seung Won Lee, Dongseok Suh, Ji-Hoon Ahn
Summary: Ferroelectric thin films based on ALD technology have been extensively studied as promising candidates for next-generation devices. By using a cyclopentadienyl-based precursor, Hf-Zr-O thin films can exhibit excellent ferroelectric properties without the need for additional post-thermal processing. This new strategy opens up possibilities for ferroelectric devices with specific processing temperature constraints.
Article
Nanoscience & Nanotechnology
Seung Gyo Jeong, Hyeonbeom Kim, Sung Ju Hong, Dongseok Suh, Woo Seok Choi
Summary: The paper proposes a method to control the spin-wave dynamics through nanolayer designing of the SrRuO3/SrTiO3 superlattices. By modulating the thickness of the SrTiO3 layers with atomic-scale precision, the magnetic anisotropy, anomalous Hall conductivity, and spin-wave gap can be systematically manipulated. This customization of magnetic anisotropy via nanoscale heterostructuring offers a novel control knob to tailor the magnon excitation energy for future spintronic applications.
ACS APPLIED NANO MATERIALS
(2021)
