Article
Physics, Multidisciplinary
Danwen Yuan, Hanqi Pi, Yi Jiang, Yuefang Hu, Liqin Zhou, Yujin Jia, Gang Su, Zhong Fang, Hongming Weng, Xinguo Ren, Wei Zhang
Summary: This study investigates the electronic structure and optical properties of quasi-hexagonal phase (qHP) and quasi-tetragonal phase (qTP) monolayer fullerenes. It is found that qHP is a semiconductor whereas qTP is a semimetal with highly in-plane anisotropic absorption. The anisotropy of qTP suggests its potential as a long-pursuit lossless metal and atomically thin polarizer.
SCIENCE CHINA-PHYSICS MECHANICS & ASTRONOMY
(2023)
Article
Chemistry, Physical
Yuehua Wei, Chuyun Deng, Xiaoming Zheng, Yangbo Chen, Xiangzhe Zhang, Wei Luo, Yi Zhang, Gang Peng, Jinxin Liu, Han Huang, Weiwei Cai, Qi Ge, Renyan Zhang, Xueao Zhang, Shiqiao Qin
Summary: This study investigates the thermal transport of supported WTe2 using Raman thermometry, finding different in-plane thermal conductivities along different directions. A heat manipulation model is proposed for WTe2 FET devices to effectively dissipate waste heat and prevent temperature discrepancy, providing new insights into thermal transport of anisotropic 2D materials.
Article
Chemistry, Multidisciplinary
Yusi Yang, Shun-Chang Liu, Zongbao Li, Ding-Jiang Xue, Jin-Song Hu
Summary: This review discusses recent progress in in-plane anisotropic 2D Ge-based binary materials, highlighting their structural, electrical and optical properties, as well as potential opportunities for optoelectronic applications. The advantages of anisotropic Ge-based binary materials such as simple compositions, good stability, highly anisotropic physical properties, and wide bandgap coverage enable their use in broadband photodetection from the infrared to ultraviolet region. Demonstrations of optoelectronic applications related to anisotropic properties include polarization-sensitive photodetection and polarization-based all-optical switches.
CHEMICAL COMMUNICATIONS
(2021)
Article
Multidisciplinary Sciences
Yong Zhu, Lei Tao, Xiya Chen, Yinhang Ma, Shoucong Ning, Jiadong Zhou, Xiaoxu Zhao, Michel Bosman, Zheng Liu, Shixuan Du, Sokrates T. Pantelides, Wu Zhou
Summary: Point defects in anisotropic ReSe2 offer potential for defect engineering, with vacancies, isoelectronic substitutions, and antisite defects being investigated through experimental and computational methods. The results provide atomic-scale insight into defect engineering of ReSe2, paving the way for tuning its electronic structure.
Article
Physics, Applied
Yuanyuan Cui, Shuqi Li, Xiangping Zhang, Tingjun Wang, Xinyu Cao, Shaohua Yan, Xiao Zhang, Hechang Lei, Gang Tang, Jiawang Hong, Xueyun Wang
Summary: The directional dependence of Young's modulus of two-dimensional niobium oxide diiodide (NbOI2) thin flakes was determined using atomic force microscopy-based nanoindentation technique. The Young's moduli along the c-axis and a-axis were found to be 97.27 +/- 62.12 GPa and 51.516 +/- 8.21 GPa, respectively. The anisotropic ratio of up to 1.89 is the highest reported so far in two-dimensional materials.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Applied
Zhun Liu, Jing Wu, Jingbo Li
Summary: In2Se3 polymorphs exhibit diverse physical properties such as piezoelectricity, photoelectricity, and ferroelectricity, which are strongly influenced by the atomic bonding arrangement in the crystal phases. A novel layered alpha '-In2Se3 phase with atom-oriented anisotropic properties was discovered using first-principles calculations, offering potential applications in optoelectronic devices with switchable anisotropic properties.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Physics, Condensed Matter
Ping Wu, Zhen-Gang Shi, Xiongwen Chen, Xiaoying Zhou
Summary: In this paper, we study the Landau levels and magneto-optical properties of black phosphorus under an in-plane magnetic field. Analytical and numerical methods are used to obtain the Landau levels and selection rules for magneto-optical transitions. The results show that the magneto-optical properties depend on the polarization direction of the light, and the magneto-optical conductance is significantly higher for light polarized along the armchair direction.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2023)
Article
Polymer Science
Dimitar Shandurkov, Nina Danchova, Tony Spassov, Vesselin Petrov, Roumen Tsekov, Stoyan Gutzov
Summary: A one-pot sol-gel method was developed to incorporate reproducible gold nanoparticles (AuNPs) with sizes of 20-40 nm into SiO2 gels. The AuNPs' chemical composition, optical properties, and size distribution in the gels were affected by variations in the preparation conditions. Organic dopants such as oleic acid, acetic acid, or dodecanethiol were used to modify the composite material and control the reduction and growth rate of the AuNPs in the gels. The synthesized samples were characterized using various methods, including UV/Vis/NIR spectroscopy, X-ray diffraction, transmission electron microscopy, thermal conductivity measurements, and DTA/TG measurements. The incorporation of AuNPs led to an increase in the thermal conductivity of the silica gels. The optimal process involved using NaOH as a gelation catalyst and oleic acid as an organic modifier to disperse 20 nm AuNPs in the silica matrix.
Article
Optics
Baizhong Li, Pengkun Li, Lu Zhang, Ruifeng Tian, Qinglin Sai, Mingyan Pan, Bin Wang, Duanyang Chen, Youchen Liu, Changtai Xia, Hongji Qi
Summary: Sb-doped S-Ga2O3 crystals were grown using the OFZ method, and they showed high quality according to X-ray diffraction and rocking curves. Raman spectra indicated Sb substitutions in the octahedral lattice. The carrier concentration, electronic mobility, and electrical resistivity of Sb-doped crystals varied with increasing Sb doping concentration. The S-Ga2O3 crystals had good transmittance in the visible region, but decreased in the infrared region due to the increased carrier concentration. Transmittance in the UV region was high, with a cutoff edge at 258 nm.
CHINESE OPTICS LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Xinli Ma, Jing Zhang, Jiawei Lai, Mingwen Zhang, Jingchuan Zheng, Sen Wu, Xiaodong Hu, Qinsheng Wang, Xuetao Gan, Dong Sun, Jing Liu
Summary: This study introduces Re doping to produce monolayer MoS2 with valley degree of freedom and anisotropy, achieving improved electrical and optoelectrical performances. The anisotropic optical response of Re-doped MoS2 increases with Re concentration, indicating promising potential for developing polarization sensitive valleytronic devices. The anisotropic response is attributed to strain induced by dopants, preserving optical helicity dependent valley selection rules in the 2H lattice structure.
Article
Nanoscience & Nanotechnology
Sergio Puebla, Roberto D'Agosta, Gabriel Sanchez-Santolino, Riccardo Frisenda, Carmen Munuera, Andres Castellanos-Gomez
Summary: The in-plane anisotropy of molybdenum trioxide (MoO3) has attracted increasing attention from the scientific community, with observed properties stemming from the material's anisotropic refractive index and elastic constants. Raman and micro-reflectance measurements were used to determine the angular dependence of the refractive index of thin MoO3 flakes, while the directional dependence of the MoO3 Young's modulus was studied using the buckling metrology method. It was found that MoO3 exhibits one of the largest in-plane anisotropic mechanical properties reported for 2D materials.
NPJ 2D MATERIALS AND APPLICATIONS
(2021)
Article
Chemistry, Physical
Jayashri Mahapatro, Sadhana Agrawal
Summary: The present work focuses on the synthesis and characterization of M-type BaFe12-xGdxO19 (x = 0, 1, 1.25, 1.5, 1.75 and 2 mol%) ceramics. The ceramics were prepared using auto combustion synthesis technique and analyzed using various techniques including structural analysis, optical and electrical property investigations. The results showed that the prepared ceramics possessed a hexagonal structure, exhibited good optical characteristics, and demonstrated potential for use in microwave devices.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Materials Science, Ceramics
Abhiram Jagannathan, Jagannath Gangareddy, R. Rajaramakrishna, K. M. Rajashekara, S. Venugopal Rao, J. Kaewkhao, S. Kothan, A. El-Denglawey
Summary: This study focuses on the optical properties of Au-Ag bimetallic nanoparticles doped in dichroic glasses, highlighting the importance of precursor materials (AgNO3, AgCl, and AgI). The incorporation of silver and gold in the glass matrix reduces nanoparticle size and enhances the nonlinear refractive index, with potential overlap of surface plasmon resonance of Ag and Au. Differences in bandgap energy due to different dopants impact the nonlinear optical properties of the nanoparticles.
JOURNAL OF NON-CRYSTALLINE SOLIDS
(2021)
Article
Chemistry, Inorganic & Nuclear
Habib Chenaina, Charfeddine Messaadi, Jalila Jalali, Hatem Ezzaouia
Summary: This study focuses on sol-gel derived SnO2-TiO2 thin films deposited on silicon wafer type Si (100) substrate using spin coating technique, followed by heat treatments at four different temperatures. XRD characterization reveals the formation of nano-crystalline phase at 400 degrees C and further crystallization with increasing annealing temperature. Optical and dielectric properties analysis demonstrates universal many body response over a broad frequency range, presenting variations in structure and performance of the films.
INORGANIC CHEMISTRY COMMUNICATIONS
(2021)
Article
Chemistry, Physical
Zhihui Chen, Qi Zhang, Menglong Zhu, Hao Chen, Xinyun Wang, Si Xiao, Kian Ping Loh, Goki Eda, Jianqiao Meng, Jun He
Summary: The nonlinear optical properties of three 2D organic-inorganic hybrid perovskites were systematically studied, revealing similar anisotropy configurations for both two-photon and three-photon photoluminescence. However, the anisotropies of third harmonic generation signals strongly depend on the specific crystal structures of the individual flakes.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Nanoscience & Nanotechnology
Adeel Liaqat, Yiheng Yin, Sabir Hussain, Wen Wen, Juanxia Wu, Yuzheng Guo, Chunhe Dang, Ching-Hwa Ho, Zheng Liu, Peng Yu, Zhihai Cheng, Liming Xie
Summary: As the size of metal oxide semiconductor field-effect transistors (FETs) is scaled down, power dissipation becomes a major challenge. The use of negative capacitance (NC) effect enables a new path to achieve a low sub-threshold swing (SS) below the Boltzmann limit. In this work, a NC-FET from an all two-dimensional (2D) metal ferroelectric semiconductor (MFS) vertical heterostructure has been demonstrated, showing steep slopes switching over a wide range of source-drain current.
Article
Nanoscience & Nanotechnology
Cheng-Chieh Lin, Kai-Di Yang, Min-Chuan Shih, Shao-Ku Huang, Tzu-Pei Chen, Hung-Chang Hsu, Ching-An Chuang, Chih-Ying Huang, Lucas Wang, Chia-Chun Chen, Ching-Hwa Ho, Ya-Ping Chiu, Chun-Wei Chen
Summary: This study demonstrates the presence of internal built-in electric fields (BIEFs) in 2D organic-inorganic hybrid Ruddlesden-Popper perovskites (OIRPPs). The strength of these BIEFs reduces with increased quantum well width. The origin of these BIEFs is attributed to molecular dipoles pointing to the organic-inorganic interfaces. This discovery provides deep insight into understanding the optical properties of 2D OIRPPs for the future design of large-area and low-cost perovskite optoelectronic devices.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Materials Science, Multidisciplinary
Adzilah Shahna Rosyadi, Alvin Hsien-Yi Chan, Jia-Xin Li, Chang-Hua Liu, Ching-Hwa Ho
Summary: This study focuses on impurity doping experiments in 2D transition-metal dichalcogenides (TMD). Different carrier types were observed under different chromium doping concentrations. Structural and optical characterization revealed that the crystal structure and bandgap of chromium-doped ReSe2 remained unchanged.
ADVANCED OPTICAL MATERIALS
(2022)
Article
Nanoscience & Nanotechnology
Tian-Yun Chang, Po-Liang Chen, Pei-Sin Chen, Wei-Qing Li, Jia-Xin Li, Ming-Yuan He, Jen-Te Chao, Ching-Hwa Ho, Chang-Hua Liu
Summary: This study demonstrates the potential of using band-engineered van der Waals hetero-structures as bias-selectable photodetectors. By tuning the bias polarity, the spectral photoresponse can be switched between different bands, showing high external quantum efficiency and fast operation speed.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Physics, Applied
Wei Li, Jeng-Yu Ke, Yun-Xuan Ou-Yang, Ying-Xuan Lin, Ching-Hwa Ho, Kuei-Yi Lee, Shunjiro Fujii, Shin-ichi Honda, Hideaki Okado, Masamichi Naitoh
Summary: In this study, MoS2 bulk was synthesized using the chemical vapor transport method, and the thickness of MoS2 flakes was limited through mechanical exfoliation. The MoS2 characteristics were transformed from n-type to p-type using oxygen plasma treatment to fabricate a p-n homogeneous junction, and the charge neutrality point shift was successfully demonstrated using FET measurement. The MoS2 p-n homogeneous junction diode showed excellent p-n characteristic curve and performed great rectifying behavior in the half-wave rectification experiment.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Multidisciplinary Sciences
Ewa Zuberek, Martyna Majak, Jakub Lubczynski, Joerg Debus, Kenji Watanabe, Takashi Taniguchi, Ching-Hwa Ho, Leszek Bryja, Joanna Jadczak
Summary: Monolayers of transition-metal dichalcogenides with direct band gap located at specific points in the Brillouin zone show promising applications in opto- and spin-electronics due to enhanced Coulomb interactions and specific spin-valley properties. Processes demonstrating the upconversion of light into bright intravalley excitons in WS2 monolayers provide insight into various interactions, including resonant optical phonons, cooling of resident electrons, and non-local electron-hole exchange. Temperature-dependent studies on excitonic upconversion intensity suggest increased phonon population and thermally enhanced electron scattering in two-dimensional quantum materials, shedding new light on excitonic properties and photonic upconversion mechanisms in van der Waals heterostructures.
SCIENTIFIC REPORTS
(2022)
Article
Nanoscience & Nanotechnology
Luthviyah Choirotul Muhimmah, Yu-Hong Peng, Feng-Han Yu, Ching-Hwa Ho
Summary: This study investigated the structural and optical properties of full-series multilayer GaTe1-xSex (0 ≤ x ≤ 1). Experimental results showed that the GaTe1-xSex layers may contain hexagonal (H) phase and monoclinic (M) phase, with the H-phase dominating when x ≥ 0.5. The photon emission energy of the M-phase GaTe1-xSex increased as the Se content increased, while that of the H-phase GaTe1-xSex decreased in the red to near-infrared (NIR) region. The decay lifetime of the band-edge emission was faster in the M phase than in the H phase for 0 ≤ x ≤ 0.4. The predominantly H phase GaTe1-xSex showed greater dark resistivity and photoconductive response under visible-light illumination. The GaTe1-xSex multilayers demonstrated superior light-emission and photodetection capability for future optoelectronic devices.
NPJ 2D MATERIALS AND APPLICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Po-Liang Chen, Tian-Yun Chang, Pei-Sin Chen, Alvin Hsien-Yi Chan, Adzilah Shahna Rosyadi, Yen-Ju Lin, Pei-Yu Huang, Jia-Xin Li, Wei-Qing Li, Chia-Jui Hsu, Neil Na, Yao-Chang Lee, Ching-Hwa Ho, Chang-Hua Liu
Summary: This study presents a two-terminal mid-infrared (mid-IR) emitter that allows control of spectral characteristics and polarization states by tuning the polarity of the applied bias. The emitter consists of back-to-back p-n junctions formed by stacking anisotropic light-emitting materials (black phosphorus and black arsenic-phosphorus with MoS2). The emissions of the two junctions exhibit distinct spectral ranges and polarization directions, and can be independently activated depending on the polarity of the applied bias.
Article
Chemistry, Physical
Joanna Jadczak, Janusz Andrzejewski, Joerg Debus, Ching-Hwa Ho, Leszek Bryja
Summary: Germanium monosulfide with an anisotropic puckered crystalline structure has unique optical and electronic properties, but the understanding of exciton-phonon interactions is limited. In this study, we investigate the resonant Raman scattering and photoluminescence of the optically active Gamma-exciton in layered GeS flakes, revealing the coupling between phonons and photogenerated carriers as well as the efficiency of multiorder scattering in optical processes.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Thalita Maysha Herninda, Chin En Hsu, Hung-Chung Hsueh, Ching-Hwa Ho
Summary: Two-dimensional semiconductors based on black phosphorus (BP) structure have attracted significant attention recently due to their strong in-plane anisotropy and potential applications in polarized optoelectronic devices, axial-dependent carrier transport, and asymmetric 2D electronic and energy devices. In this study, multilayered SnS1-xSex chalcogenides were grown by chemical vapor transport and exfoliated on a SiO2/Si substrate for optical characterization. The results showed strong in-plane anisotropy, with the maximum Raman intensity of the AM chain vibration mode (Ag) being mutually orthogonal to the ZZ chain-oriented mode (B1g) in the full-series multilayer SnS1-xSex compounds. A physical mechanism of symmetry breaking was proposed to explain the increased number of separated Ag and B1g modes with different energies for intermediate compositions compared to binary compounds of SnS and SnSe. Additionally, the bandgap value of the ZZ polarized direction was found to be lower than that of the AM direction for each of the SnS1-xSex compounds.
MATERIALS TODAY ADVANCES
(2023)
Article
Chemistry, Physical
Joanna Jadczak, Joerg Debus, Justyna Olejnik, Ching-Hwa Ho, Kenji Watanabe, Takashi Taniguchi, Leszek Bryja
Summary: This study investigates the upconversion of exciton photoluminescence in MoSe2 monolayers. The resonant interaction between high-order exciton complexes and K-valley phonons leads to enhanced emission in the trion and biexciton transitions.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Ching-An Chuang, Feng-Han Yu, Bo-Xian Yeh, Anna Milatul Ummah, Adzilah Shahna Rosyadi, Ching-Hwa Ho
Summary: Near-band-edge emissions from red to blue colors have been detected in full-series GaSe1-xSx multilayers. The crucial phase responsible for direct recombination and emission of free excitons within the visible range is identified as the & epsilon;-stacked phase. The multilayer GaSe1-xSx represents a well-suited 2D chalcogenide series for emitting full-color visible light.
ADVANCED OPTICAL MATERIALS
(2023)
Article
Engineering, Electrical & Electronic
Meng-Yu Tsai, Chia-Tse Huang, Che-Yi Lin, Mu-Pai Lee, Feng-Shou Yang, Mengjiao Li, Yuan-Ming Chang, Kenji Watanabe, Takashi Taniguchi, Ching-Hwa Ho, Wen-Wei Wu, Mahito Yamamoto, Jiunn-Lin Wu, Po-Wen Chiu, Yen-Fu Lin
Summary: A reconfigurable field-effect transistor based on a hexagonal boron nitride/rhenium diselenide/hexagonal boron nitride heterostructure offers nonvolatile control of polarity through photoinduced trapping mechanism and can emulate synaptic functions.
NATURE ELECTRONICS
(2023)
Article
Chemistry, Physical
Anna Milatul Ummah, Yu-Hung Peng, Ching-Hwa Ho
Summary: This work investigates the structural, optical, and vibrational behaviors of MnPS3 and discovers the N'eel ordering transformation through temperature-dependent structure and optical measurements. It is found that MnPS3 exhibits high magnon-phonon coupling in the antiferromagnetic state, which is influenced by the ordered spin in the 3d orbital of the Mn2+ cation. The study also detects band-edge excitons of thin-layered MnPS3 through micro-thermoreflectance measurements, revealing a magnetic transition from antiferromagnetic to paramagnetic ordering below the Neel temperature.
Letter
Chemistry, Physical
Joanna Jadczak, Janusz Andrzejewski, Joerg Debus, Ching-Hwa Ho, Leszek Bryja
Summary: Germanium monosulfide with a puckered crystalline structure has unique optical and electronic properties, which have attracted much attention. However, the interactions between excitons and phonons have not been fully understood. In this study, we investigated the resonant Raman scattering and photo-luminescence of the optically active Gamma-exciton in layered GeS flakes. We found that there is a considerable coupling between phonons and photogenerated carriers in GeS flakes, and multiorder scattering plays an important role in optical processes.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
