Article
Chemistry, Multidisciplinary
Kathrin Kroth, Philip Klement, Limei Chen, Sangam Chatterjee, Peter J. Klar
Summary: Tip-induced optical spectroscopy can overcome the resolution limits of conventional optical techniques for studying sub-nm sized objects. However, there are restrictions for spatially extended samples due to perturbations caused by the tip. Additionally, the optical response is influenced by the type of tip and substrate used.
Article
Chemistry, Multidisciplinary
Parmeet Dhindsa, David Solti, Christian R. Jacobson, Anvy Kuriakose, Gopal Narmada Naidu, Aaron Bayles, Yigao Yuan, Peter Nordlander, Naomi J. Halas
Summary: This study provides direct insight into the role of catalyst molecular structure in controlling the morphology of aluminum nanocrystals (Al NCs) by systematically modifying the catalyst molecular structure.
Article
Chemistry, Multidisciplinary
Eli Janzen, Hannah Schutte, Juliette Plo, Adrien Rousseau, Thierry Michel, Wilfried Desrat, Pierre Valvin, Vincent Jacques, Guillaume Cassabois, Bernard Gil, James H. Edgar
Summary: The changes in the properties of hexagonal boron nitride (hBN) induced by isotopic purification are reported. The study extends the purification to N-15 isotopes. Raman and photoluminescence spectroscopies show that the monoisotopic hBN crystals exhibit similar vibrational and optical properties to N-14 purified hBN. The growth of high-quality h(10)B(14)N, h(11)B(14)N, h(10)B(15)N, and h(11)B(15)N crystals opens up new possibilities for thermal conductivity control and advanced functionalities in quantum technologies.
ADVANCED MATERIALS
(2023)
Article
Engineering, Mechanical
Yuyang Long, Zonghuiyi Jiang, Zhida Gao, Baowen Li, Xuemei Li, Xiaofei Liu, Jun Yin, Wanlin Guo
Summary: Strain engineering is commonly used to tune the band structure of two-dimensional materials, but achieving nonvolatile biaxial strain remains challenging. In this study, we demonstrated that bubbles formed during mechanical exfoliation can be used as a platform to investigate the work function tunability of 2D materials under biaxial strains. We revealed in situ the equi-biaxial tensile strain at the bubble vertex, which varies with bubble sizes, and found that the local work function of ReS2 increases with biaxial tensile strain.
EXTREME MECHANICS LETTERS
(2023)
Article
Physics, Applied
Yuanyuan Chu, Yuxiang Sang, Yizhe Liu, Yingmei Liu, Zhicheng Xu, Jianxin Chen, Fang Liu, Shengjuan Li, Bo Sun, Xingjun Wang
Summary: In this study, high-quality lattice-matched and mismatched strained GaAs1-xSbx (0.37 < x < 0.57) sub-micrometer epilayers were grown on InP by molecular beam epitaxy. The thermal conductivity of GaAsSb epilayers was accurately extracted and a reduction in thermal conductivity was observed for lattice-mismatched samples with Sb = 37.9% and Sb = 56.2%, attributed to biaxial strain induced by lattice mismatch.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Chemistry, Multidisciplinary
Md Tarik Hossain, Tadasha Jena, Upasana Nath, Manabendra Sarma, P. K. Giri
Summary: The success of non-van der Waals two-dimensional bismuth oxyselenide crystals in optoelectronics has opened up opportunities to explore their fundamental properties. However, the origin of photoluminescence and the effect of growth substrates on the structure and optical properties of these crystals remain unclear. This study reveals that the formation of multiple excitons in momentum valleys is responsible for broadband absorption and visible photoluminescence in few-layer thick bismuth oxyselenide. It also demonstrates that different growth substrates introduce strain and doping, thereby modulating the morphology, absorption, and photoluminescence properties.
Article
Chemistry, Multidisciplinary
Ming Liu, Kaoru Hisama, Yongjia Zheng, Mina Maruyama, Seungju Seo, Anton Anisimov, Taiki Inoue, Esko Kauppinen, Susumu Okada, Shohei Chiashi, Rong Xiang, Shigeo Maruyama
Summary: Coaxial synthesis of single-walled and multiwalled molybdenum disulfide (MoS2) nanotubes on boron nitride nanotubes (BNNTs) was achieved by removing single-walled carbon nanotubes (SWCNTs) from heteronanotubes. Single-walled MoS2 nanotubes exhibit direct bandgap structure around 6-7 nm diameter, with a transition from indirect to direct gap above 5.2 nm. Presence of SWCNTs in BNNTs and single-walled MoS2 nanotubes significantly quenches the PL signal.
Article
Physics, Applied
Heng Wu, Yan Zhou, Yu-Xin Cai, Miao-Ling Lin, Lijun Zhang, Ping-Heng Tan
Summary: In this study, the interlayer modes in few-layer InSe were systematically investigated using low-frequency Raman spectroscopy. It was found that the commonly used linear chain model is inadequate in accurately describing the frequencies of interlayer shear modes in InSe due to the influence of weak in-plane intralayer In-In bonding. Our study reveals the non-negligible contribution of weak intralayer bonding to the corresponding interlayer vibrations in two-dimensional materials.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Applied
Ahmad Azizimanesh, Tara Pena, Arfan Sewaket, Wenhui Hou, Stephen M. Wu
Summary: This study presents a controllable approach to selectively strain MoS2 by depositing thin film stressors and utilizing lithographic patterning. By examining the strain distribution within MoS2 and exploring the directionality of strain induced by stressors, the researchers demonstrate the potential to engineer strain in 2D materials for a wide variety of applications. This opens up possibilities for creating strain patterned devices with strain-tunable properties through micro/nanolithographic design.
APPLIED PHYSICS LETTERS
(2021)
Article
Chemistry, Physical
Javier Garcia-Alonso, David Maestre, Emilio Nogales, Ana Cremades, Bianchi Mendez
Summary: In this study, NiGa2O4 microneedles with variable morphology and dimensions were successfully synthesized by an autocatalytic Vapor-Liquid-Solid process. The crystallographic facets and inversion degrees of the spinel structure were found to vary with the temperatures employed during the synthesis. The high crystallinity and preferred orientation of the structures allowed for the study of Raman vibrational modes and the observation of defect-related and near-bandgap emissions in photoluminescence measurements.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Materials Science, Multidisciplinary
K. Chandrakanta, R. Jena, P. Pal, Md F. Abdullah, S. D. Kaushik, A. K. Singh
Summary: In this study, cobalt-modified brownmillerite KBFO polycrystalline was synthesized through solid-state reaction. The Co substitution led to a decrease in optical bandgap energy and a shift in Raman peaks towards lower wavenumber. Additionally, the dielectric constant and dielectric loss of KBFCO decreased at room temperature compared to KBFO, indicating a reduction in oxygen migration and modification in response to vibrational modes.
INTERNATIONAL JOURNAL OF MINERALS METALLURGY AND MATERIALS
(2021)
Article
Chemistry, Analytical
Ge Song, Hongzhao Sun, Jian Chen, Zhigang Chen, Boyang Liu, Zhenghui Liu, Shan Cong, Zhigang Zhao
Summary: There is great research interest in building semiconductor-based SERS platforms, and this study demonstrates the use of MoO3·xH2O quantum dots to achieve highly efficient SERS sensing of small inorganic molecules. The study highlights the crucial role of the quantum size effect in enhancing SERS activity in semiconductor-based materials.
ANALYTICAL CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Jing Wang, Xiaofei Yue, JunQiang Zhu, Laigui Hu, Ran Liu, Chunxiao Cong, Zhi-Jun Qiu
Summary: Two-dimensional InSe has great potential as a candidate for novel optoelectronic devices due to its large electron mobility and near-infrared optical band gap. However, its widespread use is hindered by environmental instability. Although many theoretical studies have been conducted on the degradation mechanism of InSe, experimental evidence is lacking and the role of the extrinsic environment during degradation is still unclear. In this work, we developed a laser-treated method to systematically study the photo-induced degradation process of InSe. Our experimental results reveal different evolution behaviors of photoluminescence intensity under weak and strong laser irradiation, indicating the simultaneous occurrence of vacancy passivation and degradation under weak irradiation, while severe destruction caused by excess heating and intense oxidation under strong irradiation. This work provides valuable experimental insights into the photo oxidation study of InSe and offers a new approach to regulate the photoluminescence of InSe.
Article
Chemistry, Analytical
Ge Song, Hongzhao Sun, Jian Chen, Zhigang Chen, Boyang Liu, Zhenghui Liu, Shan Cong, Zhigang Zhao
Summary: There is a strong research interest in constructing highly effective semiconductor-based SERS platforms, but current tuning methods have not been successful in creating sensors for small inorganic molecules. This study demonstrates the use of MoO3 middotxH2O quantum dots for sensitive detection of hydrazine and other probe molecules, utilizing the quantum size effect to enhance SERS activity.
ANALYTICAL CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Erik Pollmann, Stephan Sleziona, Tobias Foller, Ulrich Hagemann, Claudia Gorynski, Oliver Petri, Lukas Madauss, Lars Breuer, Marika Schleberger
Summary: This study presents a method to access the realistic metal-semiconductor interface by exfoliating single-layer MoS2 on gold surfaces, allowing for direct measurement of charge neutrality levels. By combining various findings, the researchers successfully explained the anomalous Raman signature of MoS2 in contact with metals, shedding light on the mechanism of Fermi level pinning at the MoS2-gold interface.
Article
Chemistry, Multidisciplinary
Hao Li, Gabriel Sanchez-Santolino, Sergio Puebla, Riccardo Frisenda, Abdullah M. Al-Enizi, Ayman Nafady, Roberto D'Agosta, Andres Castellanos-Gomez
Summary: The study demonstrates that applying uniaxial strain to ZrSe3 results in a blueshift of excitonic features, with the shift magnitude depending on the direction of strain application.
ADVANCED MATERIALS
(2022)
Article
Engineering, Electrical & Electronic
Xianggang Zhang, Zhuochen Cai, Zhe Kang, Huiwen Zhai, Ziang Yin, Wanqi Jie, Tao Wang
Summary: Gamma/neutron dual detection is important in homeland security and nuclear energy development. Cs2LiLaBr6 (CLLB) has shown both dual-mode detection capability and excellent scintillation properties. The study of the Cs2LaBr5-LiBr phase diagram provides insights into the growth of high-quality CLLB crystals.
IEEE TRANSACTIONS ON NUCLEAR SCIENCE
(2022)
News Item
Optics
Jorge Quereda, Andres Castellanos-Gomez
Summary: Directional control of exciton diffusion is achieved using surface acoustic waves, enabling the guiding of exciton flux over micrometre distances even at room temperature.
Article
Nanoscience & Nanotechnology
Siqi Hu, Xiaoguang Luo, Jinpeng Xu, Qinghua Zhao, Yingchun Cheng, Tao Wang, Wanqi Jie, Andres Castellanos-Gomez, Xuetao Gan, Jianlin Zhao
Summary: This work realizes the ambipolarity of indium selenide (InSe) through van der Waals integration with metal electrodes, which eliminates the Fermi-level pinning at the metal/semiconductor interfaces. Based on this, controllable polarity InSe field-effect transistors (FETs) and p-n diodes are reconstructed, demonstrating high-performance switching and photodetection characteristics. This work paves a promising way for reconfigurable InSe-based complementary electronics and optoelectronics.
ADVANCED ELECTRONIC MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Onur Cakiroglu, Joshua O. Island, Yong Xie, Riccardo Frisenda, Andres Castellanos-Gomez
Summary: This work introduces an automated three-point bending apparatus for studying strain engineering and straintronics in 2D materials. The system is benchmarked by obtaining reproducible strain tuned micro-reflectance, Raman, and photoluminescence spectra for monolayer MoS2, which agree well with literature results. Additionally, the system is used to investigate the piezoresistive effect and strain effect on photoresponse in an MoS2 electrical device. The construction details of the system are provided, and it is anticipated to be easily implemented for studying strain engineering and straintronics in various 2D material systems.
ADVANCED MATERIALS TECHNOLOGIES
(2023)
Article
Chemistry, Multidisciplinary
Lucia Martin-Perez, Samara Medina Rivero, Manuel Vazquez Sulleiro, Alicia Naranjo, I. Jennifer Gomez, Maria Luisa Ruiz-Gonzalez, Andres Castellanos-Gomez, Mar Garcia-Hernandez, Emilio M. Perez, Enrique Burzuri
Summary: The recent development of magnetic layered van der Waals (vdW) materials has provided a platform to study exotic magnetism in two-dimensional (2D) limit. However, conventional magnetometry techniques are not suitable for directly probing the magnetic properties of 2D flakes, especially antiferromagnetic ones. In this study, an alternative approach using liquid-phase exfoliation (LPE) method was employed to obtain few-layer FePS3 flakes, which were then measured using a conventional SQUID magnetometer. The results showed direct magnetic evidence of the antiferromagnetic transition in the few-layer flakes, with a reduction in Neel temperature as the flake thickness decreased.
Article
Crystallography
Xianggang Zhang, Zhuochen Cai, Kejing Liu, Jinbo Liu, Ziang Yin, Qinghua Zhao, Aizhong Yue, Fa Luo, Tao Wang
Summary: This article reports on the excellent scintillation properties of the lanthanum crystal Cs2LiLaBr6 (CLLB) for gamma/neutron discrimination. It was found that an initial melt with hyper-peritectic ratios (55 < LiBr/mol.% < 61) was beneficial for CLLB crystal growth. The dendrite growth and peritectic reaction near the peritectic point were discovered for the first time in CLLB single crystal ingots. The Cs2LaBr5-LiBr phase diagram was modified based on these findings. The understanding of phase transition and dendrite evolution can guide the crystal growth of CLLB and other similar elpasolite crystals.
JOURNAL OF CRYSTAL GROWTH
(2023)
Article
Chemistry, Physical
Qinghua Zhao, Peng Chen, Dan Zheng, Tao Wang, Andres Castellanos-Gomez, Riccardo Frisenda
Summary: This study demonstrates a multifunctional device based on the van der Waals semiconductor Indium Selenide (InSe), which can function as a high-quality Schottky diode and a memory. By depositing the InSe channel onto graphite and platinum electrodes and implementing air passivation treatment, the device exhibits adjustable Schottky barrier height and photovoltaic parameters. This multifunctional behavior is attributed to trap state modulation.
Article
Chemistry, Physical
Yigit Sozen, Juan J. Riquelme, Yong Xie, Carmen Munuera, Andres Castellanos-Gomez
Summary: This paper presents a method for scaling up the production of flakes of van der Waals materials through mechanical exfoliation. The method utilizes a roll-to-roll setup and an automatized, massive parallel exfoliation process to produce tapes with a high density of nanosheets. This low-cost method allows for large scale fabrication of devices while maintaining good scalability and performance.
Article
Nanoscience & Nanotechnology
Felix Carrascoso, Hao Li, Jose M. Obrero-Perez, Francisco J. Aparicio, Ana Borras, Joshua O. Island, Angel Barranco, Andres Castellanos-Gomez
Summary: By using an adamantane plasma polymer pinning layer, we achieve unprecedented crystal strains of 2.8% in monolayer molybdenum disulfide. The strain gauge factors for the A and B excitons of monolayer MoS2 are reported as -99.5 meV/% and -63.5 meV/%, respectively, with a 50 nm adamantane capping layer. Photoluminescence and Raman measurements on the same samples confirm these results. Overall, our study demonstrates that adamantane polymer is an exceptional capping layer for transferring substrate-induced strain to a 2D layer and achieving higher levels of crystal strain.
NPJ 2D MATERIALS AND APPLICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Hao Li, Tayfun Kutlu, Felix Carrascoso, Hasan Sahin, Carmen Munuera, Andres Castellanos Gomez
Summary: Strain engineering is used to tune the optical, electrical, and vibrational properties of 2D nanomaterials. In this study, a four-point bending apparatus is used to apply compressive and tensile strain to black phosphorus flakes. Polarized Raman spectroscopy is then used to analyze the vibrational modes of the flakes under uniaxial strain. The results show a strong anisotropic blue/redshift in certain vibrational modes under compressive/tensile strain. Density functional theory calculations reveal that the strain-induced regulation of bond angle, bond length, and interlayer interaction contributes significantly to the observed Raman shift.
ADVANCED MATERIALS INTERFACES
(2023)
Article
Nanoscience & Nanotechnology
R. Munoz, E. Lopez-Elvira, C. Munuera, F. Carrascoso, Y. Xie, O. Cakiroglu, T. Pucher, S. Puebla, A. Castellanos-Gomez, M. Garcia-Hernandez
Summary: We demonstrate outstanding photo-responsivity, R > 10(3) A/W, fast response (similar to 0.1 s), and broad sensitivity in graphene/MoS2 photodetectors. Our devices, based on deterministic transfer of MoS2 onto directly grown graphene on sapphire, outperform previous photodetectors using large-scale grown graphene. We also present a protocol for direct growth of transparent, highly conductive, uniform, continuous graphene films on sapphire using plasma-assisted chemical vapor deposition.
NPJ 2D MATERIALS AND APPLICATIONS
(2023)
Article
Nanoscience & Nanotechnology
Thomas Pucher, Pablo Bastante, Federico Parenti, Yong Xie, Elisabetta Dimaggio, Gianluca Fiori, Andres Castellanos-Gomez
Summary: This study demonstrates the feasibility of using biodegradable material albumen as a gate dielectric for fabricating single-layer MoS2 field-effect transistors. The introduction of albumen results in high carrier mobilities and photoresponsive properties in the MoS2 transistors, indicating the potential application of albumen in optoelectronic devices.
NPJ 2D MATERIALS AND APPLICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Kejing Liu, Zhengyi Sun, Ziang Yin, Xianggang Zhang, Qinghua Zhao, Wanqi Jie, Tao Wang
Summary: In this study, we investigated the chemical reactions between trace moisture and raw Cd materials by intentionally introducing H2O. X-ray photoelectron spectra showed that residual moisture can react with raw Cd and generate more CdO compared to untreated Cd. We also modified a self-designed crucible for the removal of moisture and reaction products. The study provides a comprehensive description of the moisture-driven oxidation behavior of Cd responsible for the sticking problem of the Cd/SiO2 system and may guide high-quality Cd-based crystal growth techniques.