Article
Chemistry, Physical
Chao Ping Liu, Chun Yuen Ho, Kingsley O. Egbo, Zhan Hua Li, Cong Kang Xu, Kin Man Yu
Summary: Highly mismatched alloys offer unique opportunities for controlling electronic band structures and optoelectronic properties, with specific effects observed in ZnO1-xTex alloys synthesized over a range of compositions. The introduction of certain dopants leads to distinct changes in material conductivity and band structures, revealing potential applications for tailored device functionality.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Materials Science, Multidisciplinary
Hassan Allami, Jacob J. Krich
Summary: The study focuses on the modification of band structures and the impact on plasmons in Highly Mismatched Alloys (HMAs) due to the introduction of alloying elements. The distribution of states in the split bands causes plasmons in HMAs to behave differently than in standard materials. The effective mass of the lower split band changes with alloy fraction, affecting the plasmon frequency in a unique way compared to traditional materials.
Letter
Chemistry, Physical
Jun Hyuk Chang, Dongju Jung, Hak June Lee, Doyoon Shin, Youngdu Kim, Donghyo Hahm, Xinbiao Wang, Doh C. Lee, Euyheon Hwang, Young-Shin Park, Wan Ki Bae
Summary: The excitonic states in ZnSe1-XTeX nanocrystals and their photophysical characteristics were investigated, and it was found that nearest-neighbor Te pairs in ZnSe1-XTeX alloys create localized hole states, explaining the broadening of emission line widths and delayed recombination dynamics.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Chemistry, Physical
V. V. Romaka, G. Rogl, G. Binder, H. Michor, J. Bursik, A. Grytsiv, G. Giester, P. Rogl
Summary: Phase relations and physical properties of Sc-rich compounds in Sc-T-Ga ternary systems have been investigated, revealing the existence of various binary phases and ternary compounds.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Physics, Multidisciplinary
Bakhtiar Ul Haq, S. AlFaify, R. Ahmed
Summary: In this study, the thermoelectric properties of hexagonal- and square-shaped monolayers of ZnO were investigated for renewable energy applications. It was found that the 110-monolayer exhibited high electrical conductivities and substantial Seebeck coefficients, making it suitable for high-temperature thermoelectric device applications.
EUROPEAN PHYSICAL JOURNAL PLUS
(2021)
Article
Physics, Multidisciplinary
R. Garreis, A. Knothe, C. Tong, M. Eich, C. Gold, K. Watanabe, T. Taniguchi, V Fal'ko, T. Ihn, K. Ensslin, A. Kurzmann
Summary: Transport measurements through a few-electron circular quantum dot in bilayer graphene show bunching of conductance resonances in groups of four, eight, and twelve, which are related to the spin and valley degeneracies. As the electron numbers increase, the single-particle ground state evolves into a threefold degenerate minivalley ground state, confirmed by measurements in a magnetic field. The importance of Hund's second rule for spin filling of quantum dot levels is emphasized, highlighting the effects of exchange interactions.
PHYSICAL REVIEW LETTERS
(2021)
Article
Engineering, Electrical & Electronic
Muhammad Shakil Shah, Fareeha Yasmeen, Syeda Rabia Ejaz, Rabia Yasmin Khosa, Muhammad Imran, Mohammed A. Assiri, Imtiaz Ahmad, Naseeb Ahmad, Abdul Rauf Khan, Hafiz Muhammad Tahir Farid
Summary: The magnetic and metallic properties of the magnesium-rich intermetallic compound NdNiMg15 were studied, with the metallic nature attributed to Nd 4f electrons. The compound exhibits stability in the G-type antiferromagnetic phase and could potentially be used in magnetic probes.
JOURNAL OF ELECTRONIC MATERIALS
(2021)
Article
Engineering, Environmental
Jingyu Sun, Shudi Mo, Ze Zhang, Jinghong Wen, Donggang Guo, Yaohua Li, Lu Liu
Summary: In this study, two-dimensional BiOBr nanomaterials with oxygen-rich and oxygen-poor vacancies were designed and their photocatalytic activities were investigated. It was found that the oxygen-rich BiOBr exhibited higher antibacterial activity under NIR light irradiation due to its optimized electronic structure, which resulted in stronger interactions with bacteria, higher absorption capacity to NIR light, and longer photocarrier lifetime. The DFT calculations also showed that the oxygen-rich BiOBr had better O2 adsorption, leading to the generation of more reactive oxygen species for superior activity.
CHEMICAL ENGINEERING JOURNAL
(2022)
Article
Materials Science, Multidisciplinary
Tuan V. Vu, O. Y. Khyzhun, A. A. Lavrentyev, B. Gabrelian, V. Sabov, M. Y. Sabov, M. Y. Filep, A. Pogodin, I. E. Barchiy, A. O. Fedorchuk, B. Andriyevsky, M. Piasecki
Summary: In this study, a centimeter size crystal of silver- and bismuth-bearing selenophosphate, AgBiP2Se6, was grown for the first time by Bridgman technique and characterized via different experimental and theoretical techniques. The AgBiP2Se6 compound was found to have a well-defined layered structure and highly anisotropic optical constants, making it a promising optoelectronic semiconductor. Theoretical analysis revealed the dominance of Se p states in the upper section of the valence band, Ag d states in the central section, and P p states in the bottom section.
MATERIALS CHEMISTRY AND PHYSICS
(2022)
Article
Chemistry, Physical
Jing Wu, Wenda Zhong, Chenfan Yang, Wenli Xu, Rong Zhao, Hui Xiang, Qin Zhang, Xuanke Li, Nianjun Yang
Summary: Water electrolysis is a promising approach to produce green hydrogen, but the full utilization of electrocatalysts for promoting hydrogen evolution reaction (HER) is still challenging. In this study, a nonstoichiometric titanium sulfide/nickel sulfide (TiS2-x/NiS) hetero-catalyst was designed to induce high-density sulfur vacancies, resulting in excellent HER performance. The presence of sulfur vacancies regulates the electronic structure of active sites, leading to reduced energy barrier for water dissociation and optimized adsorption free energy for H* intermediates. This strategy provides a new way to design high-performance and cost-effective HER electrocatalysts in universal media.
APPLIED CATALYSIS B-ENVIRONMENTAL
(2022)
Article
Chemistry, Multidisciplinary
Xiao Han, Ailin Liu, Shihao Wang, Yuanyuan Liu, Saichao Li, Yinggan Zhang, Hongfei Zheng, Baisheng Sa, Laisen Wang, Jie Lin, Baihua Qu, Qingshui Xie, Dong-Liang Peng
Summary: High-capacity Li-rich layered oxides (LLOs) experience structure degradation due to hybrid anion- and cation-redox activity. A new artificial post-cycled structure is created to suppress anion redox activity and modulate cation mixing, resulting in improved electrochemical properties and voltage stability. The modified DSL-2% Li-rich cathode shows high discharge capacities even under harsh conditions, outperforming the pristine LLO. This artificial post-cycled structure provides insights into sustaining the lattice structure of lithium-depleted regions and designing stable intercalated materials with anionic redox activity.
Article
Chemistry, Inorganic & Nuclear
Xiaoshuang Li, Fei Liang, Tianpeng Liu, Haifeng Li
Summary: By introducing halogens to the A/Ga/Q (A = Na, K; Q = S, Se) system, a new chalcohalide Na2GaS2Cl with a layered structure was successfully synthesized. This compound has a high concentration of Na+ cations and a large interlayer spacing, providing a favorable environment for Na+ ion storage and migration. Additionally, the band gap of Na2GaS2Cl is determined by [GaS4] groups and Na-Cl ionic bonding.
DALTON TRANSACTIONS
(2021)
Article
Chemistry, Physical
H. V. S. Pessoni, A. Franco Jr
Summary: The influence of structural defects on the magnetic properties of Co-doped ZnO polycrystalline ceramics was investigated, and it was found that with increasing Co concentration, the saturation magnetization decreased and changed to antiferromagnetic and paramagnetic ordering. Additionally, the high-temperature sintering process resulted in the increase of antiferromagnetic ordering due to the homogenous dilution of Co ions in the ZnO structure.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Chemistry, Physical
I. S. Fathima, Raihan Ahammed, Pradip Nandi, Ashima Rawat, Abir De Sarkar
Summary: Berry curvature, the effective magnetic field in k space, can be controlled through mechanical strain to achieve better control over valley polarization. SnS monolayer shows interesting electronic properties and enhanced Berry curvature under achievable compressive strain, which may extend the lifetime of valley polarized excitons.
APPLIED SURFACE SCIENCE
(2023)
Article
Chemistry, Multidisciplinary
Abishek K. Iyer, Jeong Bin Cho, Hye Ryung Byun, Michael J. Waters, Shiqiang Hao, Benjamin M. Oxley, Venkat Gopalan, Christopher Wolverton, James M. Rondinelli, Joon Jang, Mercouri G. Kanatzidis
Summary: The study investigated the crystal structures and optical properties of mixed cation compounds Na1-xKxAsSe2 (x = 0.8, 0.65, 0.5) and Na0.1K0.9AsS2, revealing that the interaction between different ratios of K atoms can affect the properties and band gap of the compounds.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Energy & Fuels
Tooru Tanaka, Shuji Tsutsumi, Katsuhiko Saito, Qixin Guo, Kin Man Yu
Summary: By doping Cl-doped ZnTeO, the photocurrent induced by two-step photon absorption in intermediate band solar cells is significantly improved. The high activation energy of Cl donor increases the activation temperature of TSPA current, while the introduction of electrons by Cl doping helps improve the open circuit voltage of IBSCs.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2022)
Article
Chemistry, Physical
Pengfei Guo, Da Liu, Xia Shen, Qihang Lv, Yu Wu, Qian Yang, Pu Li, Yuying Hao, Johnny C. Ho, Kin Man Yu
Summary: This study reports a direct vapor-phase growth of high-quality CsPbCl3/CsPbI3 axial perovskite heterostructure and multi-heterojunction nanowires using a newly developed magnetic-pulling chemical vapor deposition approach. The structures exhibit crystalline properties with dual-wavelength emissions, demonstrating the formation of unique heterostructures. The capability to synthesize on-wire heterostructures represents a major step toward high-integration optoelectronic circuits and nanophotonics.
Article
Energy & Fuels
Yuanhang Cheng, Zixin Zeng, Tianyuan Liu, Ying Wang, Carlos D. Rodriguez-Gallegos, Haohui Liu, Xixia Liu, Maung Thway, David Khup, Aung Myint Khaing, Kin Man Yu, Sai-Wing Tsang, Fen Lin
Summary: Energy production of perovskite-based photovoltaic technology can be increased by improving device efficiency and using innovative concepts, such as bifacial and tandem configurations. The use of amorphous CdO-In2O3 alloy film in PVSCs and tandem solar cells has shown promising results, with high bifaciality factor and champion power conversion efficiency. Further efforts are needed to reduce manufacturing cost and achieve competitive LCOE values in countries with relatively low PV installation cost.
Article
Chemistry, Physical
Kingsley O. Egbo, Timothy C. Chibueze, Abdulrafiu T. Raji, Chinedu E. Ekuma, Chao Ping Liu, Kin Man Yu
Summary: Reliable bipolar carrier transport remains a challenge in most wide-gap oxide semiconductors. Stabilizing ZnO with the metastable hexahedral rocksalt structure and achieving p-type doping using alloying methods have been proposed. Li doping is found to improve the electrical properties of the Zn-rich NixZn1-xO alloy oxides, making them desirable for potential transparent optoelectronic applications.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Physics, Applied
Chun Yuen Ho, Ying Wang, Chao Ping Liu, Kin Man Yu
Summary: Bandgap energies in wurtzite structured CdxZn1-xO alloys decrease with increasing Cd content. This study synthesized pure wurtzite phase CdxZn1-xO thin films with different Cd contents in an oxygen-rich environment. The changes in structural, electrical, and optical properties of these films after rapid thermal annealing were investigated. The results demonstrate a practical way to obtain low-gap oxide semiconductors with strong optical absorption and controllable electrical conductivities.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
HyoChang Jang, Katsuhiko Saito, Qixin Guo, Kin Man Yu, Tooru Tanaka
Summary: The effects of Al doping on the properties of RS-ZnCdO thin films were studied. It was found that Al incorporation led to single-crystal layers and increased electron concentration. The films with Al doping exhibited a high optical bandgap, making them suitable for transparent conductors in full-spectrum solar cells.
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
(2022)
Article
Materials Science, Multidisciplinary
Nazmul Ahsan, Naoya Miyashita, Kin Man Yu, Wladek Walukiewicz, Yoshitaka Okada
Summary: The unique electronic features of highly mismatched alloys are suitable for the application of intermediate band solar cells. However, in realistic GaNAs IBSC, the collection of photocarriers is low and there are S-shape kink features in the current-voltage curves, which require further research and optimization.
JOURNAL OF PHOTONICS FOR ENERGY
(2022)
Article
Chemistry, Physical
Chioma Vivian Ezeh, Kingsley O. Egbo, Jamaal-Deen Musah, Kin Man Yu
Summary: Gallium oxide (Ga2O3) has attracted significant interest for its wide bandgap and unique properties. Researchers have successfully modified the electronic bands of Ga2O3 through alloying with NiO to achieve p-type conducting Ga2O3-NiO thin films. The films exhibited different structural properties and optical behaviors depending on the Ni content. The p-type alloy films with a high concentration of Ni vacancies showed a wide tunability of bandgap and sub-gap absorption.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Chemistry, Physical
Ying Wang, Yuen Yan Chow, Cheuk Kai Gary Kwok, Yau Fung Leung, Kin Man Yu
Summary: This study systematically investigated the properties of CdO films doped with transition metal donors Mo and W. The results showed that Mo and W can enhance the electron mobility of CdO films, and the performance of the materials can be further improved by controlling the rapid thermal annealing temperature.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Chemistry, Physical
Xiao Hu Lv, Zhan Hua Li, Yuan Shen Qi, Tooru Tanaka, Qi Xin Guo, Kin Man Yu, Chao Ping Liu
Summary: Amorphous p-type transparent (Ga2O3)1-x(Cu2S)x alloy thin films with x<-0.5 have been successfully synthesized by magnetron sputtering at room temperature in this study. The optical bandgap decreases from -4.8 eV to -2.5 eV with increasing x, while the hole concentration N increases from 1019 cm-3 to -2 x 1021 cm-3, with a hole mobility of -0.3 cm2 V-1 s-1. The hole transport in these amorphous alloys follows the variable-range-hopping mechanism in the temperature range of 120-300 K. The upshift of the valence band maximum (VBM) position by -3 eV with x > 0.2 enhances the p-type conductivity of the films. These amorphous p-type transparent (Ga2O3)1-x(Cu2S)x alloy thin films show potential significance in bipolar device applications, such as Ga2O3 based p-n heterojunction power devices and high-efficiency solar cells.
APPLIED SURFACE SCIENCE
(2023)
Article
Chemistry, Physical
Cheuk Kai Gary Kwok, Ying Wang, Xingyu Shu, Kin Man Yu
Summary: p-Type SnO can be oxidized into n-type SnO2, and we successfully fabricated an all-Tin Oxide transparent pn quasi-homojunction. Comparison with a p-SnO/n-ZnO heterojunction showed similar rectification behavior. XPS measurements revealed type II band offsets in both SnO2 and ZnO at the Gamma point, with respective valence band (conduction band) offsets of 2.8 eV (1.9 eV) and 2.4 eV (1.33 eV). The SnO/SnO2 p-n structure exhibited reasonable rectification with an ideality factor of -12.3, suggesting potential applications in transparent p-n junction devices.
APPLIED SURFACE SCIENCE
(2023)
Article
Chemistry, Physical
Chioma Vivian Ezeh, Kingsley O. Egbo, Kin Man Yu
Summary: In this study, p-type conductivity of Ni x Ga1-x O1+& delta; is improved by extrinsic p-type doping with Li. The doping efficiency of Li is enhanced in O-rich alloys Ni x Ga1-x O1+& delta;. With further optimization of the doping concentration, p-n junction structures can be formed on n-type Ga2O3.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Materials Science, Multidisciplinary
Kin Man Yu, Wei Zhu, Ying Wang, Yajie Li, Chaoping Liu, Guibin Chen, Wladek Walukiewicz
Summary: Doping CdO with transition metal elements (CdO:TM) can increase the electron concentration but decrease the electron mobility, resulting in limited optical transparency.
PHYSICAL REVIEW MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Sujit Kumer Shil, Fei Wang, Kingsley O. Egbo, Ying Wang, Cheuk Kai Gary Kwok, Sai-W. Tsang, Johnny C. Ho, Kin Man Yu
Summary: This work reports the synthesis and properties of Pb-free all-inorganic Cs3Sb2X9 perovskite thin films (X = I, Br) by a two-step CVD approach. These films exhibit good crystallinity and high exciton binding energies with large Stokes shifts. The optical bandgaps and refractive indices of the films were also determined. Photoconductive devices fabricated using these films exhibited commendable performance with high responsivity and detectivity, as well as stable switching properties. The long-term stability of the thin films, even without encapsulation, suggests their potential for various optoelectronic devices.
JOURNAL OF MATERIALS CHEMISTRY C
(2023)
Article
Materials Science, Multidisciplinary
Xia Shen, Qihang Lv, Qian Yang, Jie Fan, Xiaohang Song, Pengfei Guo, Pu Li, Johnny C. C. Ho, Kin Man Yu
Summary: A two-step growth of CdSxSe1-x alloy nanoribbon heterostructures along the lateral direction by an improved two-step magnetic-pulling chemical vapor deposition (CVD) method is reported. Photoluminescence spectrum and 2D emission mapping at the junctions show two different emission bands at 555 and 603 nm, which show agreement with the structural characterization results. Additionally, photodetectors based on these achieved nanoribbons exhibit great performance of high responsivity, high external quantum efficiency, fast response speed, and high I-on/I-off ratio.
ADVANCED PHOTONICS RESEARCH
(2023)