Article
Optics
Gaofang Li, Xiaobo Nie, Yuao Liao, Wen Yin, Wei Zhou, Yanqing Gao, Nenghong Xia, Haoyang Cui
Summary: Ultrafast carrier dynamics and terahertz conductivity of intrinsic 6H-SiC are studied using optical-pump terahertz-probe spectroscopy. The results show that the increase in photogenerated carrier density affects the fast decay time and the evolution of complex conductivity, and the Drude-Smith model provides a better fit for the conductivity.
OPTICS COMMUNICATIONS
(2022)
Article
Optics
Irina A. Kolesnikova, Daniil A. Kobtsev, Ruslan A. Redkin, Vladimir I. Voevodin, Anton V. Tyazhev, Oleg P. Tolbanov, Yury S. Sarkisov, Sergey Yu. Sarkisov, Victor V. Atuchin
Summary: The time dynamics of nonequilibrium charge carrier relaxation processes in SI GaAs:EL2 and HR GaAs:Cr were studied using the optical pump-terahertz probe technique, revealing that Auger recombination mechanisms dominate at high injection levels, while SRH recombination prevails at low carrier concentrations. HR GaAs:Cr was found to have a shorter charge carrier lifetime than SI GaAs:EL2 at injection levels above 10(16) cm(-3).
Article
Nanoscience & Nanotechnology
Jiahua Cai, Sai Chen, Chunyan Geng, Jianghao Li, Baogang Quan, Xiaojun Wu
Summary: We investigate the nonlinear modulation dynamics of a THz-nano metasurface on silicon substrates using a time-resolved strong-field THz-pump THz-probe (TPTP) technique. The self-modulation phenomenon with a frequency shift of about 50 GHz is achieved by switching the THz field strength. This phenomenon is attributed to the impact ionization (IMI) of the silicon substrate under the excitation of strong THz fields in nano-gaps.
Article
Nanoscience & Nanotechnology
Long Yuan, Rabin Pokharel, Shisir Devkota, Hirandeep Kuchoor, Kendall Dawkins, Min-Cheol Lee, Yue Huang, Dzmitry Yarotski, Shanthi Iyer, Rohit P. Prasankumar
Summary: Recent advances in the growth of III-V semiconductor nanowires hold great promise for nanoscale optoelectronic device applications. In this study, ultrafast optical pump-terahertz probe spectroscopy was used to investigate the impact of nitrogen incorporation on non-equilibrium charge carrier dynamics and transport in Te-doped GaAsSb and dilute nitride GaAsSbN nanowires. The results revealed the effects of nitrogen incorporation on carrier scattering rate, carrier mobility, carrier lifetime, and optical conductivities in dilute nitride nanowires.
Article
Engineering, Electrical & Electronic
Woo-Jung Lee, Gyuseok Lee, Dae-Hyung Cho, Kang Chul, Nosoung Myoung, C. S. Kee, Yong-Duck Chung
Summary: Investigating the effects of H+ ion irradiation on a chalcogenide Cu(In,Ga)Se-2 (CIGS) thin film revealed a conversion from p- to n-type conductivity, induced by strong surface band bending and ultrafast behavior of photocarriers. The use of optical pump THz probe spectroscopy further showed the ultrafast photocarrier dynamics at surface and bulk defect states, indicating H+ ion irradiation pacifies Cu vacancy defects while generating new defect states.
IEEE TRANSACTIONS ON TERAHERTZ SCIENCE AND TECHNOLOGY
(2021)
Article
Nanoscience & Nanotechnology
Aleksander M. Ulatowski, Michael D. Farrar, Henry J. Snaith, Michael B. Johnston, Laura M. Herz
Summary: Tin-iodide perovskites are promising semiconductors for photovoltaic applications due to their higher intrinsic charge-carrier mobilities and lower toxicity. A novel spectroscopic technique was experimentally implemented to investigate the intraband relaxation dynamics of charge carriers in these materials, revealing a push-induced decrease in terahertz conductivity from stimulated THz emission. The study showed that newly photogenerated charge carriers relax quickly on a subpicosecond timescale in the presence of a large population of charge carriers.
Article
Physics, Applied
Bo Wang, Gaoshuai Wei, Jianing Chen, Li Wang
Summary: This study investigates ultrafast spin polarization in semi-insulating GaAs using terahertz time-domain spectroscopy. The results demonstrate that the transmitted and reflected terahertz signals exhibit different dynamic evolutions under the excitation of different polarization laser pulses, indicating the generation and relaxation process of spin-polarized electrons.
APPLIED PHYSICS LETTERS
(2022)
Article
Chemistry, Physical
Zhiying Bai, He Zhang, Jiaqi He, Dawei He, Jiarong Wang, Guili Li, Jinxuan Bai, Kun Zhao, Xiaohui Yu, Yongsheng Wang, Xiaoxian Zhang
Summary: This study investigates the effect of pressure on the carrier transport performance and relaxation process of MoSe2 using a spatiotemporal resolved pump-probe setup. The results show that pressure can effectively tune the transport performance, enhancing the carrier mobility and shortening the carrier lifetimes. The combination of enhanced mobility and shortened lifetimes holds great potential for optoelectronic applications under extreme conditions.
Article
Materials Science, Multidisciplinary
Yiqiang He, Qiong Lei, Chunguang Li, Yu Han, Zhan Shi, Shouhua Feng
Summary: This paper focuses on how the structural defects in photocatalysts can be used to improve the efficiency of CO2 photoreduction, with an emphasis on the impact of defects on the electronic structure and charge carrier dynamics of the photocatalysts. Various defective semiconductors are discussed, and the challenges and prospects of defect engineering in the photoreduction of CO2 are analyzed.
Article
Chemistry, Multidisciplinary
Han Li, Yating Ma, Zhongjie Xu, Xiang'ai Cheng, Tian Jiang
Summary: This study observed anomalous interlayer coupling and giant PL enhancement in artificially twisted bilayers of MoS2, laying the groundwork for future advancements and applications beyond TMDCs monolayers.
Article
Chemistry, Multidisciplinary
K. P. Mithun, Shalini Tripathi, Ahin Roy, N. Ravishankar, A. K. Sood
Summary: We investigated carrier relaxation dynamics in semiconducting tellurium nanowires using ultrafast time-resolved terahertz spectroscopy. The relaxation process was found to exhibit bi-exponential decay with two time scales depending on the amount of capping agent on the TeNWs surface. A coupled rate equation model was used to quantitatively understand the relaxation mechanisms and the observed temperature-dependent dynamics. Furthermore, the frequency-dependent THz photoconductivity was modeled using the Boltzmann transport equation, revealing the contributions of short range and Coulomb scattering rates in the relaxation process.
Article
Chemistry, Multidisciplinary
K. P. Mithun, Srabani Kar, Abinash Kumar, D. V. S. Muthu, N. Ravishankar, A. K. Sood
Summary: Collective excitation of Dirac plasmons in graphene and topological insulators has led to tunable plasmonic materials. Using OPTP spectroscopy, plasmonic oscillations in bismuth telluride nanowires were demonstrated, showing a Lorentzian response with a resonance frequency shifting with photogenerated carrier density. Modulation depth was found to be tunable by pump fluence, and the time evolution of the system represented a long relaxation channel lasting for more than 50 ps. Model of the decay dynamics highlighted contributions from surface recombination and trap mediated relaxation channels.
Article
Chemistry, Multidisciplinary
Mengjiao Li, Feng-Shou Yang, Hung-Chang Hsu, Wan-Hsin Chen, Chia Nung Kuo, Jiann-Yeu Chen, Shao-Heng Yang, Ting-Hsun Yang, Che-Yi Lin, Yi Chou, Mu-Pai Lee, Yuan-Ming Chang, Yung-Cheng Yang, Ko-Chun Lee, Yi-Chia Chou, Chen-Hsin Lien, Chun-Liang Lin, Ya-Ping Chiu, Chin Shan Lue, Shu-Ping Lin, Yen-Fu Lin
Summary: Controllable doping behavior in PdSe2 transistors can emulate the essential characteristics of photo nociceptors, with mechanisms investigated through dynamic charge transfer and scanning tunneling microscope analysis. Electrostatic gating as a neuromodulator can regulate adaptive modes in the nociceptor, improving adaptability and perceptibility. An integrated artificial nociceptor array is designed for unique image processing functions, extending the promise of defect engineered 2D electronics for advanced humanoid robots and artificial visual sensors.
ADVANCED FUNCTIONAL MATERIALS
(2021)
Article
Chemistry, Inorganic & Nuclear
Ning Chen, Fei Wang, Xu Li, Xinji Yang, Hao Chen, Zhi Tan, Jie Xing, Jianguo Zhu
Summary: A new solid-solution ceramic LC-CBTa-xCBN is fabricated by introducing CBN into CBTa, which demonstrates optimal electrical performance.
INORGANIC CHEMISTRY
(2023)
Article
Materials Science, Multidisciplinary
Rongjun Zhao, Tai Wu, Rongshan Zhuang, Yong Hua, Yude Wang
Summary: This study designed a simple additive that can effectively improve the carrier transfer and eliminate nonradiative recombination in perovskite solar cells (PSCs), resulting in significantly higher power conversion efficiency.
ENERGY & ENVIRONMENTAL MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Shuo Sun, Jing-Yang You, Sisheng Duan, Jian Gou, Yong Zheng Luo, Weinan Lin, Xu Lian, Tengyu Jin, Jiawei Liu, Yuli Huang, Yihe Wang, Andrew T. S. Wee, Yuan Ping Feng, Lei Shen, Jia Lin Zhang, Jingsheng Chen, Wei Chen
Summary: Large-gap QSH systems were successfully fabricated by utilizing the substrate-orbital-filtering effect, which selectively filters Bi pz orbitals to generate pxy orbitals with nonzero magnetic quantum numbers. This strategy provides a general approach for designing large-gap QSH systems and exploring their topology-related physics.
Article
Chemistry, Physical
Yun Chen, Jingyu He, Shijie Wang, Yuan Ping Feng, Jun Zhou
Summary: This work reports a new type of Janus structures, Janus electrenes with different cation layers. By substituting one of the two zirconium cation layers in Zr2Cl2 with group I to III elements, nine Janus 2D materials have been generated, showing dramatically different electronic and magnetic properties. The results provide a new dimension of freedom to effectively tune the electronic and magnetic properties of electrenes, paving the way for novel applications.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Chemistry, Multidisciplinary
Xiaocang Han, Jing-Yang You, Shengqiang Wu, Runlai Li, Yuan Ping Feng, Kian Ping Loh, Xiaoxu Zhao
Summary: Transition-metal trihalides MX3 belong to a family of novel 2D magnets with topological magnons and electromagnetic properties, showing great potential in next-generation spintronic devices. However, direct atomic-scale analysis of MX3 is challenging due to their air instability, making information on stacking-registry-dependent magnetism elusive. In this study, we report a nondestructive transfer method to realize intact transfer of bilayer MX3 and provide a full spectrum of stacking orders in MX3 with atomic precision, revealing their associated magnetic ground states. The study sheds light on the structural basis of diverse magnetic orders in MX3, paving the way for modulating magnetic couplings via stacking engineering.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Materials Science, Multidisciplinary
Saba Khan, Yuan-Ping Feng, Nacir Tit
Summary: Designing 2D materials with half-metallicity is crucial for spintronic devices. By using manganese as a catalyst combined with specific metal atoms, it is possible to achieve half-metallicity, which is attributed to the ferromagnetic coupling interactions between the catalysts and periodic boundaries.
Article
Chemistry, Multidisciplinary
Lizhu Ren, Chenghang Zhou, Xiaohe Song, Herng Tun Seng, Liang Liu, Chaojiang Li, Tieyang Zhao, Zhenyi Zheng, Jun Ding, Yuan Ping Feng, Jingsheng Chen, Kie Leong Teo
Summary: Electrically manipulating magnetic moments by spin-orbit torque (SOT) has potential applications in magnetic memories and logic devices. In this study, highly textured, polycrystalline Heusler alloy MnxPtyGe (MPG) films were found to exhibit reversible switching of magnetization with low switching current density. Additionally, MPG shows a memristive characteristic and the ability for deterministic field-free switching of magnetization.
Article
Materials Science, Multidisciplinary
Wadha Alfalasi, Yuan Ping Feng, Nacir Tit
Summary: The aim of this study is to search/design transition-metal TM doped transition-metal dichalcogenide TMD monolayers that can exhibit half-metallicity. The investigation showed positive results on (Mn, Fe, and Ni)-doped MoS2 MLs and (V, Mn, Fe, and Co)-doped MoSe2 in smaller sample sizes of 4 x 4, 5 x 5, and 6 x 6 primitive cells. The disappearance of half metallicity in larger samples can be attributed to the existence of ferromagnetic-coupling interactions and a drastic change in magnetization.
Article
Engineering, Electrical & Electronic
Jiajun Linghu, Tingting Song, Tong Yang, Jun Zhou, Kimyong Lim, Chornghaur Sow, Ming Yang, Yuanping Feng, Xuezhi Wang
Summary: In this study, various stable semiconducting Zn-C compounds were discovered through particle swarm optimization and first-principles calculations. These compounds have stronger covalent Zn-C bonding characteristics compared to the metal rocksalt zinc carbide. Importantly, three of the compounds have direct or quasi-direct band gaps within the desirable energy range for optoelectronic applications. The electronic transitions across these band gaps contribute to the blue and near-infrared light emissions of carbon-doped ZnO.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2023)
Article
Chemistry, Multidisciplinary
Lizhu Ren, Liang Liu, Xiaohe Song, Tieyang Zhao, Xiangjun Xing, Yuan Ping Feng, Jingsheng Chen, Kie Leong Teo
Summary: Magnetic Weyl semimetals (MWSMs) have unconventional transport phenomena and can be electrically manipulated by spin-orbit torque (SOT). High-quality Co2MnGa film is confirmed to have MWSM state, and its magnetization and topology can be controlled electrically. Current-induced SOT switches the topological magnetic state of Co2MnGa in both 180-degree and 90-degree manners. This work opens up more possibilities for spintronic applications based on topological materials.
Article
Materials Science, Multidisciplinary
Hanwen Zhang, Eng Tuan Poh, Sharon Xiaodai Lim, Yimin Zhang, Hongye Qin, Haonan Xie, Chunnian He, Chorng Haur Sow
Summary: This study investigates the role of alkali metal halides as additives in the growth of transition metal dichalcogenides (TMDs) through chemical vapor deposition (CVD). Excessive gaseous sodium chloride (NaCl) deposition along the monolayer edges is found to induce large in situ strain, leading to high defect density and phase transition. Higher NaCl concentrations promote the coalescence of strain domains, enhancing the phase ratio and defect density. Moreover, excessive NaCl converts thermodynamic growth to kinetic growth, resulting in unique cloud-shaped MoS2 crystals.
Article
Chemistry, Physical
Zishen Wang, Jing-Yang You, Chuan Chen, Jinchao Mo, Jingyu He, Lishu Zhang, Jun Zhou, Kian Ping Loh, Yuan Ping Feng
Summary: The coexistence of charge density waves (CDWs), superconductivity, and nontrivial topology in monolayer 1H-MSe2 (M = Nb, Ta) has been observed, triggered by momentum-dependent electron-phonon coupling through electron doping. New 2 x 2 CDW phases with nontrivial topology, Dirac cones, and van Hove singularities emerge at a critical electron doping concentration. These 2 x 2 CDW phases are also found to be superconducting. This discovery provides insights into the engineering of nontrivial electronic characters and offers a platform to modulate different quantum states.
NANOSCALE HORIZONS
(2023)
Article
Chemistry, Physical
Jun Zhou, Zishen Wang, Shijie Wang, Yuan Ping Feng, Ming Yang, Lei Shen
Summary: This study reports a novel charge density wave that generates 2D ferromagnetism instead of suppressing it by forming interstitial anionic electrons as the charge modulation mechanism. This transition introduces a new magnetic form of CDWs, offering promising opportunities for exploring novel fundamental physics and advanced spintronics applications.
NANOSCALE HORIZONS
(2023)
Article
Physics, Multidisciplinary
Zishen Wang, Chuan Chen, Jinchao Mo, Jun Zhou, Kian Ping Loh, Yuan Ping Feng
Summary: This study proposes an ab initio method to accurately describe Fermi surface nesting and electron-phonon coupling (EPC), and systematically investigates their roles in the formation of charge density wave (CDW). The results show that momentum-dependent EPC leads to softening of phonon frequencies, which become imaginary (phonon instabilities) at CDW vectors. Moreover, including EPC in the mean-field model is necessary to correctly predict the distribution of electron instabilities and CDW gap opening. These findings highlight the crucial role of EPC in CDW formation. The analytical approach used in this study is applicable to other CDW systems.
PHYSICAL REVIEW RESEARCH
(2023)
Article
Materials Science, Multidisciplinary
Eng Tuan Poh, Yung Zhen Tan, Justin Boon Shuan Neo, Chee How Ong, Azianty Saroni, Zheng Zhang, Jianhui Li, Boon Tong Goh, Chorng Haur Sow
Summary: Laser-induced microscale reactions provide controllable insights into nanomaterial properties and can be used to engineer material luminescence. By modifying indium oxide nanowires with a laser, we discovered yellow and blue fluorescence. The yellow component is related to oxygen inclusions, while the blue fluorescence originates from oxygen physisorption during storage. Using the blue emission, we demonstrate micropatterns with differentiated optical encryption features for enhanced anti-counterfeiting capability.
JOURNAL OF MATERIALS CHEMISTRY C
(2023)
Article
Materials Science, Multidisciplinary
Jingyu He, Yuanzheng Chen, Zishen Wang, Ming Yang, Tong Yang, Lei Shen, Xiaoguang Xu, Yong Jiang, Jianwei Chai, Lai Mun Wong, Shijie Wang, Yuan Ping Feng, Jun Zhou
Summary: We propose a new material, ZrCl2, which can be easily exfoliated and shows a nonmagnetic-magnetic phase transition at a specific doping concentration in the monolayer form. Through theoretical calculations and simulations, we investigate the mechanism of magnetism in doped ZrCl2 and confirm the properties of these magnetic anionic electrons. Our results demonstrate the potential of electric-field controllable magnetism in electronic materials, with potential applications in spintronics.
JOURNAL OF MATERIALS CHEMISTRY C
(2022)
Article
Chemistry, Physical
Xu Gao, Yanqing Shen, Jiajia Liu, Lingling Lv, Min Zhou, Zhongxiang Zhou, Yuan Ping Feng, Lei Shen
Summary: In this work, two practical methods are proposed to address the problem in Z-scheme heterojunction photocatalysts. By introducing large interfacial polarization and using wide-bandgap components, polar heterojunctions with high driving photovoltages and photocatalytic performance are achieved.
CATALYSIS SCIENCE & TECHNOLOGY
(2022)
