Article
Materials Science, Coatings & Films
James Bork, Wilder Acuna, Joshua Zide
Summary: As a highly mismatched alloy, dilute bismuthide materials have strong valence band-Bi impurity state interactions and large bandgap bowing parameters, making them ideal for band and strain engineering in infrared devices. This study focuses on the molecular beam epitaxy growth of dilute bismuthide InxAl1-xBiyAs1-y on InP, and successfully demonstrates high-quality, droplet-free growth of films with up to 5.1% Bi.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2022)
Article
Physics, Applied
D. N. Lobanov, K. E. Kudryavtsev, M. Kalinnikov, L. Krasilnikova, P. A. Yunin, E. Skorokhodov, M. Shaleev, A. Novikov, B. A. Andreev, Z. F. Krasilnik
Summary: This study reports on stimulated emission (SE) in the near-infrared range from planar InGaN epitaxial layers grown on sapphire substrates. The research found that at temperatures around 190-210K, nonradiative recombination processes dominate the temperature quenching of stimulated emission. Different defect centers play a role in providing free electrons for both InN and InGaN layers, affecting the Shockley-Read-Hall (SRH) recombination rate at high temperatures.
APPLIED PHYSICS LETTERS
(2021)
Article
Multidisciplinary Sciences
N. J. Bailey, T. B. O. Rockett, S. Flores, D. F. Reyes, J. P. R. David, R. D. Richards
Summary: This study thoroughly investigates a series of gallium arsenide bismide device layers using low-temperature, power-dependent photoluminescence measurements. The results show that the growth temperature and bismuth beam equivalent pressure have significant effects on the localized state distributions, emission linewidths, and device properties. It is concluded that bismuth-rich surface conditions during growth are preferable for achieving the narrowest emission linewidths with this material. Furthermore, the study demonstrates how the growth mode of a gallium arsenide bismide layer can be inferred ex-situ from low-temperature photoluminescence measurements.
SCIENTIFIC REPORTS
(2022)
Letter
Optics
Satoshi Yanase, Kouichi Akahane, Atsushi Matsumoto, Toshimasa Umezawa, Naokatsu Yamamoto, Yoriko Tominaga, Atsushi Kanno, Tomohiro Maeda, Hideyuki Sotobayashi
Summary: This study investigates the effects of bismuth irradiation on InAs quantum dot lasers operating in the telecommunication wavelength band. The results show that bismuth irradiation has certain influences on the threshold current and temperature dependence of the lasers.
Article
Optics
J. Skriniarova, P. Hronec, J. Chlpik, A. Laurencikova, J. Kovac Jr, J. Novak, R. Andok
Summary: This paper focused on investigating the GaP volume fraction in GaP nanowires prepared on GaP substrates by MOVPE using VLS mode. Spectroscopic ellipsometry and scanning electron microscopy image processing methods were used, showing a good agreement. The volume fraction of GaP on the top of the nanowires ranged from 1.5% to 6.3%, while at the bottom it was between 34.8% and 39.6%.
Article
Physics, Applied
R. C. White, L. J. Nordin, A. J. Muhowski, D. Wasserman, S. R. Bank
Summary: The incorporation of dilute concentrations of bismuth into traditional III-V alloys can significantly reduce the bandgap energy and present unique opportunities in strain and bandgap engineering. This study focuses on InSb1-xBix as a candidate material and demonstrates the growth of high-quality InSb1-xBix by molecular beam epitaxy. The results suggest the potential of InSb1-xBix as an alternative emerging candidate for longwave-infrared applications.
APPLIED PHYSICS LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Honglian Song, Xiaofei Yu
Summary: This study investigated the effect of oxygen ion irradiation on the structures and optical band gap of MoSe2 continuous nano-sheets on sapphire substrates, revealing that high fluences irradiation results in lattice disorder and damage, leading to structural degradation and tensile stress in the nanosheets.
RESULTS IN PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Ethan Chi Ho Wen, Peter H. Jacobse, Jingwei Jiang, Ziyi Wang, Steven G. Louie, Michael F. Crommie, Felix R. Fischer
Summary: Substitutional heteroatom doping in 1D graphene nanoribbons is a versatile tool for low-dimensional functional materials, but previous methods only result in modest realignment of energy levels. This study introduces nitrogen core-doped armchair GNRs that yield greater energy-level shifting through the substitution of carbon atoms with nitrogen atoms along the backbone.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Materials Science, Multidisciplinary
Min Jay Kim, Kyeong Jun Lee, Hyun Don Kim, Hyuk Jin Kim, Byoung Ki Choi, In Hak Lee, Yeong Gwang Khim, Jin Eun Heo, Seo Hyoung Chang, Eunjip Choi, Young Jun Chang
Summary: This study systematically investigated the growth mechanism of ultrathin ZnTe films on GaAs (001) and found that the surface atomic ordering and single crystalline phase of the films aligned to the substrate orientation. The variation of band gap and in-gap states was obtained through spectroscopic ellipsometry analysis.
Article
Multidisciplinary Sciences
Xuezhi Ma, Qiushi Liu, Ning Yu, Da Xu, Sanggon Kim, Zebin Liu, Kaili Jiang, Bryan M. Wong, Ruoxue Yan, Ming Liu
Summary: Optical transmission and scattering spectroscopic microscopy is limited by the diffraction limit of light, but a super-resolution hyperspectral imaging technique has been developed to achieve 6 nm spatial resolution in single-walled carbon nanotubes. This technique allows for measurement of optical electronic transitions and chiral indices in nanomaterials.
NATURE COMMUNICATIONS
(2021)
Article
Chemistry, Physical
Yufeng Huang, Yaxu Wei, Yanning Li, Chunguang Hu, Wanfu Shen, Kun Zhang, Zongwei Xu, Lidong Sun
Summary: A singly oriented MoSe2 monolayer was grown on an Al2O3(11 (2) over bar0) substrate using molecular beam epitaxy (MBE). The growth process can be divided into small island growth and subsequent coalescence, with MoSe2 nuclei and domains preferentially aligning their zig-zag direction along the Al2O3[0001] direction due to the two-fold lattice symmetry of the substrate surface. The increase and decrease of optical anisotropy during island growth and coalescence, respectively, indicate the dominance of interfacial interaction with the substrate surface and the lateral interaction within the MoSe2 monolayer.
APPLIED SURFACE SCIENCE
(2023)
Article
Chemistry, Physical
Elena Hajdeu-Chicarosh, Victoria Rotaru, Sergiu Levcenko, Rosalia Serna, Ivan A. Victorov, Maxim Guc, Raquel Caballero, Jose Manuel Merino, Ernest Arushanov, Maximo Leon
Summary: This study investigated the vibrational and optical properties of Sb2Se3 and Sb2S3 polycrystalline materials using Raman scattering and spectroscopic ellipsometry. The presence of desired phases was confirmed, and optical parameters were obtained, serving as a reference for the optimal design of optoelectronic devices based on these compounds.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Physics, Applied
Fan Zhang, Xiongfeng Zhou, Ji'an Duan
Summary: An effective method was proposed to study the relationship of dielectric functions and thickness in perovskite SrRuO3 (SRO) thin film using spectroscopic ellipsometry measurement and Drude-Lorentz dispersive model. The band gap was found to be slightly enhanced with decreasing film thickness due to the one-dimensional quantum confinement effect and disorder effect. This method has potential applications for dielectric modulation in perovskite photonic devices.
APPLIED PHYSICS EXPRESS
(2021)
Article
Crystallography
V. A. Shvets, D. V. Marin, I. A. Azarov, M. V. Yakushev, S. V. Rykhlitskii
Summary: In situ temperature control is crucial for obtaining highly crystalline HgCdTe layers by molecular beam epitaxy. Spectroscopic ellipsometry is used to measure the temperature by analyzing different regions of the ellipsometric spectra of the CdTe buffer layer. The temperature measurement accuracy is several degrees with a sensitivity reaching fractions of a degree. Changes in temperature and composition during growth can be determined by studying the kinetics of ellipsometric spectra.
JOURNAL OF CRYSTAL GROWTH
(2022)
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
Physics, Multidisciplinary
Carl Willem Rischau, Yuke Li, Benoit Fauque, Hisashi Inoue, Minu Kim, Christopher Bell, Harold Y. Hwang, Aharon Kapitulnik, Kamran Behnia
Summary: The study demonstrates that in different types of superconductors, the Nernst signal corresponds to an entropy per vortex per layer of approximately k(B)ln2. The amplitude of the Nernst signal generated by ephemeral Cooper pairs above the critical temperature matches the theoretical expectations.
PHYSICAL REVIEW LETTERS
(2021)
Article
Chemistry, Multidisciplinary
Tae Gwan Park, Byoung Ki Choi, Junho Park, Jungdae Kim, Young Jun Chang, Fabian Rotermund
Summary: Atomically thin vanadium diselenide (VSe2) is a two-dimensional transition metal dichalcogenide known for its metallic 1T phase, and recent studies have shown efficient interlayer hot electron transfer in VSe2/graphene heterostructures, which can have potential applications in optoelectronic and photonic devices.
Article
Materials Science, Multidisciplinary
Hyang Keun Yoo, Luca Moreschini, Aaron Bostwick, Andrew L. Walter, Tae Won Noh, Eli Rotenberg, Young Jun Chang
Summary: This research used in situ angle-resolved photoemission spectroscopy to elucidate the mechanisms for the formation of the high-mobility conducting interface (CI) between LaAlO3 (LAO) and SrTiO3 (STO); The study shows that the built-in potential (V-bi) and oxygen gas (O-2(g)) exposure have an effect on CI formation, and UV irradiation can alter V-bi.
CURRENT APPLIED PHYSICS
(2021)
Article
Chemistry, Physical
Minu Kim, Steffen Klenner, Graham M. McNally, Juergen Nuss, Alexander Yaresko, Ulrich Wedig, Reinhard K. Kremer, Rainer Poettgen, Hidenori Takagi
Summary: The study reveals different antimony oxidation states in perovskite antimonates Ba1-xKxSbO3 at different doping levels, with the charge-density-wave order being suppressed at x=0.65, leading to the compound transitioning into a superconductor. This provides direct evidence of metal s electrons participating in the formation of CDW order and superconductivity.
CHEMISTRY OF MATERIALS
(2021)
Article
Materials Science, Multidisciplinary
Mohamed Oudah, Minu Kim, Ksenia S. Rabinovich, Kateryna Foyevtsova, Graham McNally, Berkay Kilic, Kathrin Kuester, Robert Green, Alexander Boris, George Sawatzky, Andreas P. Schnyder, D. A. Bonn, Bernhard Keimer, Hidenori Takagi
Summary: In this study, it was found that Ag2BiO3 exhibits a bond disproportionated state with holes on the oxygen atoms, supporting the presence of two different bismuth states through X-ray photoelectron spectroscopy results. The compound has an estimated band gap of approximately 1.25 eV and is expected to host Weyl nodal chains in its band structure. Additionally, similarities were highlighted between Ag2BiO3 and the well-known disproportionated bismuthate BaBiO3, with both compounds showing importance of hybridization of Bi 6s and O 2p atomic orbitals in shaping the band structure.
PHYSICAL REVIEW MATERIALS
(2021)
Article
Chemistry, Physical
Minu Kim, Graham M. McNally, Hun-Ho Kim, Mohamed Oudah, Alexandra S. Gibbs, Pascal Manuel, Robert J. Green, Ronny Sutarto, Tomohiro Takayama, Alexander Yaresko, Ulrich Wedig, Masahiko Isobe, Reinhard K. Kremer, D. A. Bonn, Bernhard Keimer, Hidenori Takagi
Summary: Superconductivity is observed in (Ba,K)SbO3, stabilized by high-pressure synthesis, with a positive oxygen-metal charge transfer energy. This discovery suggests that strong oxygen-metal covalency might be more important than the sign of the charge transfer energy in the origin of superconductivity in main-group perovskite superconductors.
Article
Nanoscience & Nanotechnology
Ganbat Duvjir, Jee-Ahn Jung, Trinh Thi Ly, Nguyen Huu Lam, Young Jun Chang, Sunghun Lee, Hanchul Kim, Jungdae Kim
Summary: In this study, the fine structure and charge distribution of the charge density wave (CDW) phase in VTe2 were investigated using a combination of scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. The results provide valuable insights for further research on the electronic structure of VTe2.
Article
Physics, Multidisciplinary
Yeong Gwang Khim, Beomjin Park, Jin Eun Heo, Young Hun Khim, Young Rok Khim, Minseon Gu, Tae Gyu Rhee, Seo Hyoung Chang, Moonsup Han, Young Jun Chang
Summary: The study finds that high-temperature growth of TiN thin films leads to significant enhancement of electrical conductivity, promising for durable and scalable electrode applications.
JOURNAL OF THE KOREAN PHYSICAL SOCIETY
(2023)
Article
Nanoscience & Nanotechnology
T. F. Schweizer, U. Niemann, X. Que, Q. He, L. Zhou, M. Kim, H. Takagi, D. Huang
Summary: By using pulsed laser deposition, we have successfully grown LiV2O4 thin films with bulklike properties on SrTiO3(111) and performed stable STM imaging of the LiV2O4(111) surface. Our STM measurements provide insights into the growth mechanisms of LiV2O4 on SrTiO3(111) and demonstrate the feasibility of performing surface-sensitive measurements of this heavy fermion compound.
Article
Materials Science, Multidisciplinary
Klara Volckaert, Byoung Ki Choi, Hyuk Jin Kim, Deepnarayan Biswas, Denny Puntel, Simone Peli, Fulvio Parmigiani, Federico Cilento, Young Jun Chang, Soren Ulstrup
Summary: This study investigates the femtosecond dynamics of photoinduced excitations in single-layer ReSe2 grown on a bilayer graphene substrate. The optical gap of ReSe2 is measured to be (1.53 +/- 0.02) eV, and the exciton distribution can be tuned by the polarization of the pump pulse. The decay of the exciton distribution has two time constants, facilitated by interlayer charge transfer and recombination via an in-gap state at the Fermi level.
PHYSICAL REVIEW MATERIALS
(2023)
Article
Nanoscience & Nanotechnology
Hyuk Jin Kim, Minsu Chong, Tae Gyu Rhee, Yeong Gwang Khim, Min-Hyoung Jung, Young-Min Kim, Hu Young Jeong, Byoung Ki Choi, Young Jun Chang
Summary: In this study, machine learning-assisted analysis of RHEED videos was used to investigate the growth of 2D thin films of transition metal dichalcogenides (ReSe2) on graphene substrates. By utilizing principal component analysis (PCA) and K-means clustering, statistically important patterns can be separated and the trend of pattern evolution can be visualized without notable loss of information. The findings demonstrate the successful application of machine learning analysis in examining and understanding the film-growth dynamics of 2D materials, and have the potential to pave the way for advanced real-time monitoring and autonomous material synthesis techniques.
Article
Materials Science, Multidisciplinary
Minseon Gu, Moon Seop Hyun, Moonsup Han, Gyungtae Kim, Young Jun Chang
Summary: The increasing demands for multi-stacked memory devices require the urgent development of backside contact electrode technologies. Two inspection methods, voltage contrast (VC)-SEM and conducting AFM (C-AFM), were investigated in this study for testing samples with different contact hole states. VC-SEM showed contrast variation at the contact holes, allowing for discerning the contact status with an optimal voltage. C-AFM demonstrated a finite electrical current in connected contacts and negligible current in disconnected ones. The insights gained from these methods are valuable for analyzing high aspect ratio contact hole technologies.
CURRENT APPLIED PHYSICS
(2023)
Article
Chemistry, Physical
Kyungtaek Lee, In Hak Lee, Yeong Gwang Khim, Suh-young Kwon, Geunweon Lim, Junha Jung, Young Jun Chang, Ju Han Lee
Summary: The potential of two-dimensional nanomaterial Cr2Te3 in nonlinear photonics has been investigated. The Cr2Te3 film shows saturable absorption and self-defocusing properties at telecommunication wavelengths. The study suggests that Cr2Te3 has broad optical applications potential.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Materials Science, Multidisciplinary
Si-Hong Lee, Yun Chang Park, Jinwoong Chae, Gunn Kim, Hyuk Jin Kim, Byoung Ki Choi, In Hak Lee, Young Jun Chang, Seung-Hyun Chun, Minkyung Jung, Jungpil Seo, Sunghun Lee
Summary: The study reports the fabrication of a perfect 1T-phase VS2 single crystal using chemical vapor transport and annealing treatment, and reveals the formation of two clear CDW orders at low temperature with the absence of nesting vectors on the Fermi surface. This finding provides important insights for further research on the physical properties of VS2.
JOURNAL OF MATERIALS CHEMISTRY C
(2022)
Article
Nanoscience & Nanotechnology
Hyuk Jin Kim, Nguyen Van Quang, Thi Huong Nguyen, Sera Kim, Yangjin Lee, In Hak Lee, Sunglae Cho, Maeng-Je Seong, Kwanpyo Kim, Young Jun Chang
Summary: This study investigates the effect of helium ion irradiation on transition metal dichalcogenide thin films and finds that helium ion irradiation can significantly improve their thermoelectric properties.
NANOSCALE RESEARCH LETTERS
(2022)