Review
Physics, Condensed Matter
Mahfujur Rahaman, Dietrich R. T. Zahn
Summary: Two-dimensional (2D) semiconductors have unique physical properties compared to other semiconducting materials, which makes them highly valuable for various applications. Raman spectroscopy is extensively used to study their physical properties, but it has limitations in advanced systems. Plasmon-enhanced Raman spectroscopy has emerged as a solution to investigate local heterogeneous information of 2D semiconductors.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2022)
Article
Chemistry, Multidisciplinary
Asia Sarycheva, Maruda Shanmugasundaram, Andrey Krayev, Yury Gogotsi
Summary: MXenes are extensively researched materials due to their unique combination of high electronic conductivity and hydrophilic surface. In this study, nanoscale Raman imaging of single-layer and few-layer Hakes of Ti3C2Tx MXene is reported using tip-enhanced Raman scattering (TERS). The absolute intensities of MXene peaks decrease with increasing number of layers, while the relative intensity of certain bands increases. The peak positions of the main MXene bands do not significantly change with different layers, suggesting weak coupling between the MXene layers. The study also reveals the stiffening of vibrations over the wrinkles in MXene Hakes.
Article
Chemistry, Physical
Pooneh Farhat, Maria Olivia Aviles, Sydney Legge, Zhiqiang Wang, Tsun-Kong Sham, Francois Lagugne-Labarthet
Summary: This article investigates the interaction between MoS2 flakes and gold nanoparticles and evaluates their plasmon-exciton coupling effect.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Chemistry, Physical
Chih-Feng Wang, Patrick Z. El-Khoury
Summary: The study reveals that nonlinear optical processes can be enhanced at plasmonic tip-sample nanojunctions, allowing for high-spatial-resolution chemical analysis through enhanced spectroscopies.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Chemistry, Multidisciplinary
Cla Duri Tschannen, Martin Frimmer, Thiago L. Vasconcelos, Lei Shi, Thomas Pichler, Lukas Novotny
Summary: This paper demonstrates the use of tip-enhanced Raman scattering (TERS) to enhance the Raman response of a single carbyne chain. The study observes a significant increase in scattering and discusses the role of coherent Stokes-anti-Stokes scattering mediated by an excited phonon. The resonance effects and laser-induced heating are also discussed, along with potential opportunities.
Review
Chemistry, Multidisciplinary
Ilya A. Milekhin, Alexander G. Milekhin, Dietrich R. T. Zahn
Summary: This study presents the optical response of spherical CdSe nanocrystals using SERS and TERS techniques, achieving significant enhancement of optical phonons by selecting appropriate plasmonic substrates. Combining Raman scattering with atomic force microscopy offers nanoscale spatial resolution for investigating phonon properties. Gap-mode TERS further enhances Raman scattering of CdSe NCs' optical phonon modes with nanometer spatial resolution, providing new pathways for optical characterization and phonon spectrum details at the nanometer scale of single semiconductor nanostructures.
Article
Chemistry, Multidisciplinary
Arijit Kayal, Sraboni Dey, G. Harikrishnan, Renjith Nadarajan, Shashwata Chattopadhyay, Joy Mitra
Summary: The extraordinary mechanical properties of two-dimensional transition-metal dichalcogenides make them ideal candidates for investigating strain-induced control of various physical properties. By exploring the role of nonuniform strain on semiconducting, chemical vapor deposited monolayer MoS2 on nanostructured substrates, this study investigates the modulation of optical, electronic, and transport properties. The findings demonstrate the accumulation of electron density at strained regions, leading to a significant increase in field effect mobility in strained samples. Furthermore, the study shows that the pattern-induced strain can be easily controlled by changing the periodicity of the nanostructures, providing a robust yet useful macroscopic control on strain and mobility in these systems.
Article
Chemistry, Multidisciplinary
Jean-Francois Bryche, Marlo Vega, Agnes Tempez, Thibault Brule, Thomas Carlier, Julien Moreau, Marc Chaigneau, Paul G. Charette, Michael Canva
Summary: This work demonstrates the enhancement in plasmonic sensing efficacy by spatially-localized functionalization on nanostructured surfaces, where probe molecules are concentrated in areas of high field concentration. SERS measurements on nanostructured surfaces with homogeneous and spatially-localized functionalization with thiophenol show that the Raman signal mainly originates from high field concentration areas. TERS measurements with 10 nm spatial resolution confirm the predicted field distribution profiles.
Article
Nanoscience & Nanotechnology
Luke R. McCourt, Ben S. Routley, Michael G. Ruppert, Vicki J. Keast, C. I. Sathish, Rohan Borah, Renee V. Goreham, Andrew J. Fleming
Summary: This Article presents a method for characterizing the imaging performance of tip-enhanced Raman spectroscopy probes. The method uses atomic force microscope maps and specific excitation methods to identify single-walled carbon nanotubes suitable for Raman scattering. High resolution cross sections of the nanotubes are collected, and point spread functions, optical contrast, and spot diameter are calculated. The method is applied to several probes, resulting in imaging recommendations and limitations summary for each probe. Elemental analysis and boundary element simulations explain the formation of multiple peaks in the point spread functions due to random grain formation on the probe surface.
ACS APPLIED NANO MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Sobin Mathew, Shilpashree Narasimha, Johannes Reiprich, Theresa Scheler, Bernd Haehnlein, Sebastian Thiele, Jaqueline Stauffenberg, Vladislav Kurtash, Saadman Abedin, Eberhard Manske, Heiko O. Jacobs, Jorg Pezoldt
Summary: A method for synthesizing bulk tetrahedral MoS2 thin films using solid source chemical vapor deposition is presented. The study analyzes the time-dependent growth morphologies and combines the results into a growth model. Various techniques like optical, electron, atomic force microscopy, Raman spectroscopy, and X-ray diffraction are utilized to study the morphological and structural features of the tetrahedral MoS2 thin layers.
CRYSTAL GROWTH & DESIGN
(2022)
Article
Chemistry, Multidisciplinary
Jing Liang, Dongyang Yang, Yunhuan Xiao, Sean Chen, Jerry I. Dadap, Joerg Rottler, Ziliang Ye
Summary: Slip avalanches are common in three-dimensional materials under shear strain and provide insights into plastic deformation, fragmentation, and earthquakes. This study provides evidence of 2D slip avalanches in exfoliated rhombohedral MoS2 triggered by shear strain near the threshold level. By using interfacial polarization, the researchers directly probed the stacking order in multilayer flakes and observed a variety of polarization domains with a power-law distribution. These findings suggest that slip avalanches can occur during the exfoliation of 2D materials and that stacking orders can be changed through shear strain. This observation has significant implications for the development of new materials and technologies, where precise control over atomic structure is crucial for optimizing properties and understanding fundamental physical phenomena.
Review
Chemistry, Multidisciplinary
Jiaqi Shao, Weitao Su
Summary: The optoelectronic properties of 2D transition metal dichalcogenide (TMD) thin layers are strongly influenced by nanoscale defects. Tip-enhanced nanoscopy, such as tip-enhanced Raman spectroscopy (TERS) and tip-enhanced photoluminescence (TEPL), has emerged as a powerful tool to characterize the localized phonon and exciton behaviors of TMDs and heterojunctions (HJs) at the nanoscale. This article summarizes the recent progress of TERS and TEPL in characterizing typical defects in TMDs, investigating local strain and its dynamic control of phonon and exciton behaviors, characterizing TMD HJs, and utilizing TERS and TEPL with optoelectronic sensitive electronic scanning probe microscopy (SPM) in TMD applications.
Article
Chemistry, Multidisciplinary
Joachim Jelken, Maria O. Aviles, Francois Lagugne-Labarthet
Summary: We report on the flower-like surface structure of tungsten disulfide (WS2) flakes grown by chemical vapor deposition (CVD). This structure is the result of a peculiar one-step growth process during CVD that allows control of sulfur concentration. The mechanical, chemical, and electronic properties of the flakes vary depending on the microscale domains, which were studied using various measurement techniques.
Article
Chemistry, Physical
Felix Carrascoso, Hao Li, Riccardo Frisenda, Andres Castellanos-Gomez
Summary: This research utilizes strain to modify the optical properties of semiconducting transition metal dichalcogenides, with a focus on MoS2, MoSe2, WS2, and WSe2. The study provides detailed technical descriptions for performing uniaxial strain measurements and proposes a calibration method for accurately determining the applied strain. Reflectance spectroscopy is then employed to analyze the strain tunability of electronic properties in single-, bi-, and tri-layer MoS2, MoSe2, WS2, and WSe2, with an assessment of flake-to-flake variability in 15 single-layer MoS2 flakes.
Article
Multidisciplinary Sciences
Kailang Liu, Xiang Chen, Penglai Gong, Ruohan Yu, Jinsong Wu, Liang Li, Wei Han, Sanjun Yang, Chendong Zhang, Jinghao Deng, Aoju Li, Qingfu Zhang, Fuwei Zhuge, Tianyou Zhai
Summary: Strain engineering is a promising method for tuning the electronic properties of 2D materials. In this study, a facile strategy for the fabrication of highly strained MoS2 via chalcogenide substitution reaction (CSR) is reported. The resulting MoS2 sustains ultra large in-plane strain with great homogeneity, with the strain tunable by varying processing temperature, potentially allowing modulation of the bandgap for device applications.
Article
Chemistry, Multidisciplinary
Yuting Deng, Yang Gao, Tiantian Li, Sutong Xiao, Mohsen Adeli, Raul D. Rodriguez, Wei Geng, Qiu Chen, Chong Cheng, Changsheng Zhao
Summary: This study develops a cobalt selenide-based biocatalyst with an amorphous Ru@CoSe nanolayer for ultrafast and broadspectrum catalytic ROS-elimination. The biocatalyst shows excellent catalase-like kinetics and can efficiently rescue the proliferation of mesenchymal stem cells in an oxidative stress environment. The study offers an effective nanomedicine for catalytic ROS-scavenging and ultrafast healing of inflammatory wounds, and provides a strategy to design biocatalytic metal compounds.
Review
Physics, Condensed Matter
Volodymyr Dzhagan, Alexander P. Litvinchuk, Mykhailo Ya Valakh, Dietrich R. T. Zahn
Summary: Ternary and quaternary metal-chalcogenides, such as CuInS2 and Cu2ZnSn(S,Se)(4), have gained significant attention for their applications in alternative energy conversion and light-emitting devices. These compounds offer more sustainable and affordable solutions compared to traditional semiconductors. However, their tolerance to non-stoichiometric compositions and polymorphism can lead to undesirable coexistence of different compounds and point defects, posing challenges for practical applications. Raman spectroscopy has emerged as a powerful tool for structural diagnostics and characterization of these compounds, especially in the context of nanostructures. This review aims to summarize the current knowledge on the phonon spectra and the capabilities of Raman and IR spectroscopies in characterizing these promising families of compounds.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2023)
Article
Physics, Applied
Yang Pan, Lu He, Ilya Milekhin, Alexander G. Milekhin, Dietrich R. T. Zahn
Summary: In this study, the local photoluminescence quenching and enhancement in the quantum tunneling regime at MoSe2/hBN/plasmonic nanostructure interfaces were investigated using monolayer MoSe2/hBN heterostructure on Au nanotriangles as an example. By utilizing tip-enhanced photoluminescence spectroscopy, the nanostructures were resolved and imaged locally. Furthermore, the competing mechanisms of localized surface plasmon resonance, electron tunneling, and highly localized strain were studied to understand the local photoluminescence quenching and enhancement at the nanoscale.
APPLIED PHYSICS LETTERS
(2023)
Article
Chemistry, Physical
N. N. Kurus, I. A. Milekhin, N. A. Nebogatikova, I. Antonova, E. E. Rodyakina, A. G. Milekhin, A. Latyshev, D. R. T. Zahn
Summary: This study focuses on enhancing Raman scattering in multilayered graphene films through plasmonic interaction. By placing the films on a plasmonic substrate consisting of arrays of gold nanodisks, resonant Raman enhancement of the main vibrational modes of multilayered graphene was achieved. The results showed a 25-fold enhancement for nanodisks with a diameter of 103 nm. Moreover, stronger local enhancement (50-fold) was obtained using gap-mode tip-enhanced Raman scattering. The study also revealed the presence of nanofolds in the graphene film, which exhibited mechanical stresses up to 0.7% and lower frequency positions for certain vibrational modes.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Engineering, Electrical & Electronic
A. Ievtushenko, V Dzhagan, O. Khyzhun, O. Baibara, O. Bykov, M. Zahornyi, V Yukhymchuk, M. Valakh, D. R. T. Zahn, K. Naumenko, P. Zaremba, S. Zagorodnya
Summary: Ag-containing ZnO nanostructures were synthesized on Ag coated Si substrates using atmospheric pressure metal-organic chemical vapour deposition. The relation between structural parameters and chemical composition with photoluminescence properties and electron-phonon coupling was investigated through XRD, XPS, and Raman spectroscopy. The position and width of the phonon Raman peaks and near bandgap PL band were found to be determined by the structural quality of the crystallites. The heat dissipation in the film, influenced by the nanostructure morphology and Ag content, played a crucial role in the behavior of phonon and PL bands.
SEMICONDUCTOR SCIENCE AND TECHNOLOGY
(2023)
Article
Chemistry, Multidisciplinary
Yevhenii Havryliuk, Volodymyr Dzhagan, Anatolii Karnaukhov, Oleksandr Selyshchev, Julia Hann, Dietrich R. T. Zahn
Summary: The problem of waste heat in solar panels has led to research on hybrid solar cells that combine photovoltaic and thermoelectric properties. One potential material for this is Cu2ZnSnS4 (CZTS). In this study, CZTS thin films were formed using green colloidal synthesis and subjected to thermal annealing or flash-lamp annealing. The optimal temperature range for obtaining conductive nanocrystalline films and determining reliable thermoelectric parameters was found to be 250-300 ?. The presence of the CuxS phase was found to be important for the electrical and thermoelectric properties of CZTS films obtained in this way.
Article
Chemistry, Multidisciplinary
Volodymyr Dzhagan, Nazar Mazur, Olga Kapush, Oleksandr Selyshchev, Anatolii Karnaukhov, Oleg A. Yeshchenko, Mykola I. Danylenko, Volodymyr Yukhymchuk, Dietrich R. T. Zahn
Summary: This study investigates the influence of the parameters of the shell and interface in semiconductor core/shell nanocrystals (NCs) on their optical properties and charge transfer, using Raman spectroscopy. The results show that the use of thioglycolic acid (TGA) during the synthesis leads to the formation of a CdS shell around the CdTe core in the NCs. The optical absorption and photoluminescence bands of these NCs are determined by the CdTe core, while the far-infrared absorption and resonant Raman scattering spectra are dominated by the vibrations related to the shell.
Article
Chemistry, Multidisciplinary
Maxim Fatkullin, Raul D. Rodriguez, Ilia Petrov, Nelson E. Villa, Anna Lipovka, Maria Gridina, Gennadiy Murastov, Anna Chernova, Evgenii Plotnikov, Andrey Averkiev, Dmitry Cheshev, Oleg Semyonov, Fedor Gubarev, Konstantin Brazovskiy, Wenbo Sheng, Ihsan Amin, Jianxi Liu, Xin Jia, Evgeniya Sheremet
Summary: Structural electronics and flexible/wearable devices can be achieved by combining polymers with metal nanoparticles. However, it is difficult to fabricate flexible plasmonic structures using conventional technologies. In this study, we developed 3D plasmonic nanostructures/polymer sensors using a single-step laser processing and functionalized them with 4-nitrobenzenethiol (4-NBT) as a molecular probe. These sensors allow ultrasensitive detection with surface-enhanced Raman spectroscopy (SERS).
Review
Chemistry, Multidisciplinary
Oleksandr Stroyuk, Oleksandra Raievska, Dietrich R. T. Zahn, Christoph J. Brabec
Summary: The review summarizes recent reports on highly efficient photoluminescence originating from self-trapped exciton states in various materials, including chalcopyrite ternary quantum dots, polyheptazine carbon nitrides, and lead-free double halide perovskites. The review outlines the photoluminescence features of these self-trapped exciton emitters and discusses the challenges and promising directions for future research.
Article
Chemistry, Physical
Serhiy Kondratenko, Oleksandr I. Datsenko, Danylo Babich, Volodymyr Dzhagan, Yang Pan, Mahfujur Rahaman, Oleksandr Selyshchev, Dietrich R. T. Zahn
Summary: This study presents the fabrication of hybrid 2D-QD MoS2-AgInS2 photoconductive devices by pressing a MoS2 flake onto an AgInS2 QD film. The devices exhibit enhanced photoresponse under continuous and modulated optical excitations, attributed to the built-in electric field near the MoS2/AgInS2 interface. The study demonstrates the potential of these devices for photovoltaic and optoelectronic applications.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Lu He, Dietrich R. T. Zahn, Teresa I. I. Madeira
Summary: Titanium dioxide (TiO2) thin films have photocatalytic properties and can be used for recycling and maintenance. Factors affecting their performance include nanocrystalline size, surface morphology, and phase composition, which need to be better studied and correlated.
Article
Nanoscience & Nanotechnology
Mahfujur Rahaman, Gwangwoo Kim, Kyung Yeol Ma, Seunguk Song, Hyeon Suk Shin, Deep Jariwala
Summary: The exciton control in transition metal dichalcogenides (TMDCs) and their heterostructures has fundamental importance for applications in optoelectronic and photonic devices. In this study, the behavior of intra- and interlayer excitons in TMDC heterobilayers under the quantum tunneling regime was explored using a metallic probe in an atomic force microscope. The results revealed significantly different exciton-plasmon coupling for intra- and interlayer excitons due to the orientation of the dipoles of the electron-hole pairs. The findings have important implications for near-field probing of excitonic materials in the strong-coupling regime.
NPJ 2D MATERIALS AND APPLICATIONS
(2023)
Article
Engineering, Biomedical
Elena Abyzova, Elizaveta Dogadina, Raul D. Rodriguez, Ilia Petrov, Yuliana Kolesnikova, Mo Zhou, Chaozong Liu, Evgeniya Sheremet
Summary: Smart implants play an increasingly important role in treating diseases, tracking patient conditions, and restoring functions. By actively stimulating nerves and monitoring essential functions, these devices improve patient observation quality and subsequent treatments. This review explores smart implant classification, the latest prototypes, materials, and technologies, with a focus on incorporating new functionality through sensors and electronic circuits in medical devices. The advantages, opportunities, and challenges of creating implantable devices that preserve critical functions are also discussed.
MATERIALS TODAY BIO
(2023)
Article
Chemistry, Multidisciplinary
Tim Voelzer, Alina Schubert, Erik von der Oelsnitz, Julian Schroeer, Ingo Barke, Rico Schwartz, Kenji Watanabe, Takashi Taniguchi, Sylvia Speller, Tobias Korn, Stefan Lochbrunner
Summary: This study investigates the charge or energy transfer-related quenching of perylene orange (PO) dye fluorescence when brought onto monolayer TMDCs via thermal vapor deposition. The results show a significant intensity drop in PO fluorescence and a relative growth of trion versus exciton contribution in TMDC emission. Fluorescence imaging lifetime microscopy confirms the intensity quenching to be around 10^3-fold and a drastic reduction in lifetime. Analysis suggests a time constant of several picoseconds at most, indicating efficient charge separation suitable for optoelectronic devices.
NANOSCALE ADVANCES
(2023)
Article
Chemistry, Multidisciplinary
Ilya Milekhin, Kirill Anikin, Nina N. Kurus, Vladimir G. Mansurov, Timur V. Malin, Konstantin S. Zhuravlev, Alexander V. Latyshev, Alexander V. Latyshev, Dietrich R. T. Zahn
Summary: We carried out local phonon analysis on single AlN nanocrystals using two complementary imaging spectroscopic techniques: tip-enhanced Raman scattering (TERS) and nano-Fourier transform infrared (nano-FTIR) spectroscopy. The TERS spectra showed strong surface optical (SO) phonon modes, with their intensities having a weak polarization dependence. The electric field enhancement from the plasmon mode of the TERS tip altered the phonon response of the sample, causing the dominance of the SO mode over other phonon modes. TERS imaging allowed for the visualization of the spatial localization of the SO mode. We successfully observed the angle anisotropy of the SO phonon modes in AlN nanocrystals with nanoscale spatial resolution. The frequency position of the SO modes in nano-FTIR spectra was determined by the excitation geometry and the local nanostructure surface profile, as demonstrated by analytical calculations.
NANOSCALE ADVANCES
(2023)
