Article
Nanoscience & Nanotechnology
Tao Hou, Sicen Tao, Haoran Mu, Qiaoliang Bao, Huanyang Chen
Summary: By combining transformation optics and van der Waals layered materials, a proposed invisibility concentrator utilizes a thin layer of alpha-MoO3 to wrap around a cylinder, inheriting invisibility and energy concentration effects. Analytical calculation and numerical simulations confirm the device's functionalities, providing guidelines for future experimental verification.
Article
Chemistry, Physical
Junfan Wang, Haojie Lai, Xiaoli Huang, Junjie Liu, Yueheng Lu, Pengyi Liu, Weiguang Xie
Summary: Two-dimensional van der Waals crystals (2D vdW) are potential materials to overcome the physical limitations caused by size scaling. In this study, vdW metal oxide MoO3 is used as the gate dielectric in a 2D field-effect transistor (FET). The device shows a threshold voltage near 0 V, high Ion/Ioff ratio, and good response to visible light, indicating the potential of MoO3 as a gate dielectric material.
Article
Chemistry, Multidisciplinary
Ravindra Kumar, Vikash Mishra, Tejendra Dixit, Prahalad Kanti Barman, Pramoda K. Nayak, M. S. Ramachandra Rao
Summary: Mono-layer transition metal dichalcogenides (TMDCs) are promising materials for studying many-body physics due to their low dimensionality and strong Coulomb interaction. The van der Waals (vdW) heterostructures (HSs) of TMDCs provide an additional degree of freedom for altering the properties of 2D materials. In this study, vdW HSs (& alpha;-MoO3/MoS2) were synthesized and their temperature-dependent photoluminescence (PL) spectra were investigated. The emergence of a new PL peak in the low-energy regime was attributed to the formation of a positive trion, which was confirmed by power and wavelength-dependent Raman and PL studies.
Article
Chemistry, Multidisciplinary
A. Bafekry, M. Faraji, A. Abdollahzadeh Ziabari, M. M. Fadlallah, Chuong Nguyen, M. Ghergherehchi, S. A. H. Feghhi
Summary: The study investigates the structural, electronic, and optical properties of the MoS2/MoSi2N4 heterostructure, finding that it has a smaller indirect bandgap and lower work function compared to individual monolayers. The heterostructure can enhance light absorption in both the ultraviolet and visible regions. The refractive index behavior of the HTS is described as a cumulative effect of the individual effects of the MoSi2N4 and MoS2 monolayers.
NEW JOURNAL OF CHEMISTRY
(2021)
Article
Chemistry, Multidisciplinary
Son-Tung Nguyen, Cuong Q. Nguyen, Nguyen N. Hieu, Huynh V. Phuc, Chuong V. Nguyen
Summary: In this study, a novel 2D metal-semiconductor MoSH@MoS2 heterostructure was constructed and its structures, electronic properties, and contact characteristics were investigated using first-principles investigations. The heterostructure showed a p-type Schottky contact, with the specific Schottky barrier height varying depending on the stacking configurations used. By modulating the electric field, the Schottky barriers could be modified and transformed from p-type to n-type. These findings provide important insights for the development of advanced electronics technology based on metal-semiconductor MoSH@MoS2 heterostructures with enhanced tunability and versatility.
NANOSCALE ADVANCES
(2023)
Article
Chemistry, Multidisciplinary
Moumita Mukherjee, Sucharita Mandal, Ayan Datta
Summary: Using ab-initio density functional theory (DFT), the friction at the atomic scale of three different carbon nitride structures (C2N/C2N, C6N6/C6N6, and C6N6/C2N) is compared. The sliding path with the lowest energy corrugations determines the static frictional forces. The homo-layer structures (C2N/C2N and C6N6/C6N6) have higher corrugation energy and higher static lateral forces compared to the hetero-layer structure (C2N/C6N6). The heterostructure has significantly lower corrugation energy due to reduced fluctuation in the interfacial charge density along the sliding pathway. Moreover, the interlayer distance change is smallest for the heterostructure.
CHEMISTRY-AN ASIAN JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Muhammad S. Ramzan, Jens Kunstmann, Agnieszka B. Kuc
Summary: Additional electron or hole layers in MoS2/WSe2 heterobilayers can modify interlayer hybridization and affect quasiparticle energy and real-space extent of electron and hole states at different valleys. The band edges can shift from K to Q or Γ with a sufficient number of additional layers, providing a powerful way to tune the properties of interlayer excitons in TMDC heterostructures.
Article
Materials Science, Multidisciplinary
Alexander A. Balandin, Fariborz Kargar, Tina T. Salguero, Roger K. Lake
Summary: The advent of graphene and other two-dimensional van der Waals materials has led to significant progress in fundamental science. This review focuses on the emerging field of one-dimensional van der Waals quantum materials, which involves atomic chains and their unique properties. The authors discuss various quantum effects, such as charge-density-wave condensate and topological phases, as well as the potential applications of these materials in composites.
Article
Nanoscience & Nanotechnology
Yuchuan Pan, Xiaochi Liu, Junqiang Yang, Won Jong Yoo, Jian Sun
Summary: Two-dimensional transition-metal dichalcogenide (TMDC) based semiconducting van der Waals (vdW) heterostructures have unique and tunable properties, and controlling carrier type and band alignment is crucial for desired performances. In this study, carrier type and band alignment in a vertical MoTe2/MoS2 heterojunction are controlled via thickness engineering and surface charge transfer doping, leading to the realization of multifunctional diodes that are universal and applicable to emerging nanoelectronics based on 2D materials.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Materials Science, Multidisciplinary
Jiang Cao, Sara Fiore, Cedric Klinkert, Nicolas Vetsch, Mathieu Luisier
Summary: This study investigates light-matter interactions and charge transport in two-dimensional van der Waals heterostructures using ab initio quantum transport method. It is found that interlayer electron-hole pairs can be generated even without phonon-assisted processes.
Article
Chemistry, Physical
Huawei Liu, Lizhen Fang, Xiaoli Zhu, Chenguang Zhu, Xingxia Sun, Gengzhao Xu, Biyuan Zheng, Ying Liu, Ziyu Luo, Hui Wang, Chengdong Yao, Dong Li, Anlian Pan
Summary: A novel contact strategy using Bi2Te3 nanosheets as van der Waals contacts on MoS2 is proposed in this study to address the poor contact quality issue in two-dimensional semiconductor-based field effect transistors (FETs). The results show that the MoS2 FET device with Bi2Te3 contacts exhibits higher performance and smaller Schottky barrier height.
Article
Materials Science, Multidisciplinary
Zegao Wang, Xuya Xiong, Jiheng Li, Mingdong Dong
Summary: By introducing an rGO buffer layer in MoS2 transistors, van der Waals contacts can be formed effectively, leading to a significant improvement in device performance.
MATERIALS TODAY PHYSICS
(2021)
Article
Materials Science, Multidisciplinary
Sergey G. Menabde, Junghoon Jahng, Sergejs Boroviks, Jongtae Ahn, Jacob T. Heiden, Do Kyung Hwang, Eun Sung Lee, N. Asger Mortensen, Min Seok Jang
Summary: Orthorhombic molybdenum trioxide (alpha-MoO3) is a polaritonic van der Waals crystal with strongly anisotropic mid-infrared phonon-polaritons. The coupling of polariton with its mirror image in an adjacent metal leads to a more confined image mode. This research measures the propagation constant of image phonon-polaritons in alpha-MoO3 using monocrystalline gold flakes as a substrate, demonstrating the long lifetime and propagation length of these polaritons.
ADVANCED OPTICAL MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Xuan Ji, Zongqi Bai, Fang Luo, Mengjian Zhu, Chucai Guo, Zhihong Zhu, Shiqiao Qin
Summary: The research team successfully fabricated MoTe2-MoS2 van der Waals heterostructure photodetectors with great performance, operating without bias voltage, high photocurrent on/off ratio, and high photoresponsivity.
Article
Chemistry, Multidisciplinary
Jialing Wen, Wenhui Tang, Zhuo Kang, Qingliang Liao, Mengyu Hong, Junli Du, Xiankun Zhang, Huihui Yu, Haonan Si, Zheng Zhang, Yue Zhang
Summary: This study introduces a new memory design using 2D graphdiyne as the charge-trapping layer, achieving a bilayer memory GDY/MoS2 with a large memory window and high degree of modulation. It demonstrates data storage capability in different operating modes, showcasing the potential for high-performance dielectric-free electronics and applications such as optical memories and artificial synaptic.
Article
Physics, Applied
Hartwin Peelaers, Joel B. Varley, James S. Speck, Chris G. Van de Walle
APPLIED PHYSICS LETTERS
(2021)
Correction
Physics, Applied
Nicholas L. Adamski, Cyrus E. Dreyer, Chris G. van de Walle
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Applied
Joseph Casamento, Hyunjea Lee, Takuya Maeda, Ved Gund, Kazuki Nomoto, Len van Deurzen, Wesley Turner, Patrick Fay, Sai Mu, Chris G. van de Walle, Amit Lal, Huili (Grace) Xing, Debdeep Jena
Summary: Epitaxial ScxAl1-xN thin films grown on metal polar GaN substrates exhibit high relative dielectric permittivity, the largest among existing nitride materials. The films also have polarization discontinuity, which can be utilized for extending transistor operation in power electronics and high-speed microwave applications.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
Xie Zhang, Mark E. Turiansky, Jimmy-Xuan Shen, Chris G. van de Walle
Summary: This Perspective critically discusses the defect tolerance in halide perovskites based on first-principles calculations. It shows that halide perovskites are not defect tolerant and suffer from defect-assisted nonradiative recombination, with comparable or higher nonradiative recombination rates than conventional semiconductors. The importance of accurate defect properties and defect engineering in improving the efficiency of perovskite solar cells is highlighted.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Physics, Applied
Joshua Leveillee, Samuel Ponce, Nicholas L. Adamski, Chris G. Van de Walle, Feliciano Giustino
Summary: The possibility of improving the hole mobility of GaN by epitaxial matching to ZnGeN2 and MgSiN2 is explored. Calculations show that lattice matching with these materials can lead to the inversion of certain hole bands and significantly increase hole mobility.
APPLIED PHYSICS LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Sai Mu, Chris G. Van de Walle
Summary: This study uses density functional theory to assess the phase stability of monoclinic Ga2O3 and (AlxGa1-x)(2)O-3 alloys. It finds that the gamma and kappa phases of (AlxGa1-x)(2)O-3 have the lowest enthalpy of formation at 62.5% and 50% Al concentrations, respectively. At finite temperature, lattice vibrations tend to stabilize the kappa phase and destabilize the alpha and gamma phases, with the configurational entropy of the gamma phase playing a substantial role in stabilizing it.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Kushal Rijal, Stephanie Amos, Pavel Valencia-Acuna, Fatimah Rudayni, Neno Fuller, Hui Zhao, Hartwin Peelaers, Wai-Lun Chan
Summary: Periodic nanoscale potentials can trap interlayer excitons by utilizing the structure deformability of a 2D molecular crystal as a degree of freedom. The PTCDI lattice on MoS2 creates a spatial variation of molecular orbital energy, providing effective trapping sites for IXs.
Article
Physics, Applied
Su-Hyun Yoo, Mira Todorova, Jorg Neugebauer, Chris G. Van de Walle
Summary: GaN/(Al, Ga)N heterojunctions are crucial for high-electron-mobility transistors. The density of the two-dimensional electron gas (2DEG) on the GaN side is significantly enhanced by the strong polarization fields at the interface. The source of the electrons in the 2DEG is intrinsic to the overall structure and the negative charge is balanced by fixed charge on the surface, rather than surface states.
PHYSICAL REVIEW APPLIED
(2023)
Article
Quantum Science & Technology
Mehmet T. Uysal, Mouktik Raha, Songtao Chen, Christopher M. Phenicie, Salim Ourari, Mengen Wang, Chris G. Van de Walle, Viatcheslav V. Dobrovitski, Jeff D. Thompson
Summary: In this work, coherent coupling between the electron spin of a single Er3+ ion and a single I = 1/2 nuclear spin in the solid-state host crystal, which is a fortuitously located proton (1H), is demonstrated. The nuclear spin is controlled using dynamical-decoupling sequences applied to the electron spin, allowing for one- and two-qubit gate operations. The longer coherence time of the nuclear spin, compared to the electron spin, is crucial for combining long-lived nuclear spin quantum registers with telecom-wavelength emitters for long-distance quantum repeaters.
Article
Physics, Multidisciplinary
Fangzhou Zhao, Mark E. Turiansky, Audrius Alkauskas, Chris G. Van de Walle
Summary: Trap-assisted Auger-Meitner recombination is highlighted as a dominant nonradiative process in wide-band-gap materials, and a first-principles methodology is presented to determine the rates of this process in semiconductors or insulators due to defects or impurities.
PHYSICAL REVIEW LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Ymir K. Frodason, Joel B. Varley, Klaus Magnus H. Johansen, Lasse Vines, Chris G. Van de Walle
Summary: Pathways and energy barriers for the migration of Ga vacancies (VGa) and Ga interstitials (Gai) in-Ga2O3 have been studied using hybrid functional calculations and the nudged elastic band method. A mechanism for the transformation of VGa between different split configurations has been described. The overall migration barriers for VGa and Gai in different crystal directions have been determined. The results provide insights into the thermally activated recovery processes in irradiated material.
Article
Materials Science, Multidisciplinary
Yubi Chen, Mark E. Turiansky, Chris G. Van de Walle
Summary: This study conducted comprehensive investigations on native point defects in beryllium oxide (BeO) using density functional theory. The stability and potential applications of different defects were analyzed, and suitable candidates for quantum defects were identified.
Article
Quantum Science & Technology
Raj N. Patel, David A. Hopper, Jordan A. Gusdorff, Mark E. Turiansky, Tzu-Yung Huang, Rebecca E. K. Fishman, Benjamin Porat, Chris G. Van de Walle, Lee C. Bassett
Summary: By using photon emission correlation spectroscopy, we revealed the optical dynamics of quantum emitters in hexagonal boron nitride. The experimental results showed the existence of quantum emitters with ideal single-photon emission and their photoluminescence emission lineshapes were consistent with individual vibronic transitions. However, polarization-resolved excitation and emission revealed the role of multiple optical transitions, and photon emission correlation spectroscopy revealed the complicated optical dynamics associated with excitation and relaxation.
Proceedings Paper
Engineering, Electrical & Electronic
Mengen Wang, Sai Mu, Chris G. Van de Walle
Summary: This paper discusses the diffusion behavior of dopants and point defects in monoclinic gallium oxide, as well as the diffusion of hydrogen in gallium oxide. The results provide important guidance for controlling doping in gallium oxide and its alloys.
OXIDE-BASED MATERIALS AND DEVICES XIII
(2022)
Article
Materials Science, Multidisciplinary
Sai Mu, Mengen Wang, Joel B. Varley, John L. Lyons, Darshana Wickramaratne, Chris G. Van de Walle
Summary: We used hybrid density functional calculations to analyze n-type doping in monoclinic (AlxGa1-x)(2)O-3 alloys. Our study focused on the impact of silicon, carbon, and hydrogen as impurities in metal-organic chemical vapor deposition (MOCVD) and their effect on the structural properties and charge-state transition levels of the alloys.
