Article
Chemistry, Multidisciplinary
Anoop Kumar Singh, Shiau-Yuan Huang, Po-Wei Chen, Jung-Lung Chiang, Dong-Sing Wuu
Summary: The study investigated the effect of thermal annealing in different ambients on the microstructural and optoelectronic properties of ZnGa2O4 films, finding that ZnGa2O4 films annealed under air ambiance exhibited excellent optoelectronic performance and quasi-single-crystalline structure, suitable for metal-semiconductor-metal photodetectors.
Article
Physics, Condensed Matter
Subham Paramanik, Soumyo Chatterjee, Amlan J. Pal
Summary: The study explores the evolution of band energies in alpha-NiS when alloyed with cadmium through isovalent doping, revealing a reverse bandgap-bowing phenomenon. The research suggests that an antagonism between volume deformation and structural relaxation resulted in the reverse bandgap-bowing in Ni1-x Cd x S alloys. This phenomenon, characterized by a negative bowing coefficient, is uncommon in chalcogenide alloys.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2021)
Article
Chemistry, Multidisciplinary
Julian Klein, Laura Kampermann, Benjamin Mockenhaupt, Malte Behrens, Jennifer Strunk, Gerd Bacher
Summary: The Tauc plot is a widely used method for determining the optical gap of amorphous semiconductors. It has also been modified to study direct and indirect interband transitions in (poly-) crystalline semiconductors. Despite its popularity, the Tauc plot should be used with caution due to the variability in electronic structure.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Yang Zhou, Simone C. W. van Laar, Daniele Meggiolaro, Luca Gregori, Samuele Martani, Jia-Yong Heng, Kunal Datta, Jesus Jimenez-Lopez, Feng Wang, E. Laine Wong, Isabella Poli, Antonella Treglia, Daniele Cortecchia, Mirko Prato, Libor Kobera, Feng Gao, Ni Zhao, Rene A. J. Janssen, Filippo De Angelis, Annamaria Petrozza
Summary: The bandgap tunability of lead mixed halide perovskites (LMHPs) is crucial for optoelectronic applications. However, the formation of iodide-rich phase under illumination destabilizes the bandgap. This study reveals that the formation of the iodide-rich phase is promoted by the presence of I-2 and the binding strength of Br- within the crystalline unit.
ADVANCED MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Shahadat H. Sohel, Ramchandra Kotecha, Imran S. Khan, Karen N. Heinselman, Sreekant Narumanchi, M. Brooks Tellekamp, Andriy Zakutayev
Summary: This study reports the fabrication and optimization of p-NiO/n-β-Ga2O3 heterojunction diodes, which demonstrate a current rectification ratio of over 106 at high temperatures. The NiO heterojunction diode exhibits higher turn-on voltage and lower reverse leakage current compared to Ni-based Schottky diodes, due to its higher built-in potential and additional band offset. These findings suggest that heterojunction p-n diodes based on β-Ga2O3 can significantly enhance the performance of high-temperature electronic devices and sensors.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2023)
Article
Physics, Multidisciplinary
Wadha Alfalasi, Iyad Al Qasir, Nacir Tit
Summary: This study used density functional theory to investigate the origins of bandgap bowing character in transition-metal-dichalcogenide ternary alloyed monolayers. It was found that common-anion ternary alloys exhibit bandgap bowing, while common-cation ternary alloys do not. The calculated results are in agreement with experimental data and have significant implications for photonic nano-device applications based on TMDs.
NEW JOURNAL OF PHYSICS
(2021)
Article
Materials Science, Multidisciplinary
Mengyu Hong, Xiankun Zhang, Yu Geng, Yunan Wang, Xiaofu Wei, Li Gao, Huihui Yu, Zhihong Cao, Zheng Zhang, Yue Zhang
Summary: Metal-semiconductor contacts play a crucial role in semiconductor devices. Researchers propose a nanobelt-assisted transfer strategy that enables the universal transfer of over 20 different types of electrodes. The contacts prepared using this strategy exhibit low Schottky barriers and adhere to the Schottky-Mott rule.
Article
Chemistry, Physical
Anoop Kumar Singh, Po-Wei Chen, Dong-Sing Wuu
Summary: Al-doped ZnGa2O4 films were deposited on sapphire substrates with varying DC power for the Al target, with the 20 W deposition showing the highest crystalline quality and wide-bandgap. X-ray photoemission spectra revealed the bonding of Al in the ZGO network, and the photodetector with the 20 W film exhibited significantly improved performance compared to the 0 W film.
APPLIED SURFACE SCIENCE
(2021)
Article
Engineering, Electrical & Electronic
Tianchen Yang, Chengyun Shou, Long Xu, Jason Tran, Yanwei He, Yuan Li, Peng Wei, Jianlin Liu
Summary: This study focuses on the application of deep-ultraviolet photodetectors and the fabrication of fi-MgGaO metal-semiconductor-metal photodetectors. Different Mg atomic percentages were used to grow fi-phase MgGaO ternary alloy thin films. The experimental results show that the alloy has an ultrawide bandgap and high light transmittance in the visible region. This study suggests the potential of fi-MgGaO semiconductors in deep-ultraviolet photodetectors and other photonic device applications.
ACS APPLIED ELECTRONIC MATERIALS
(2023)
Article
Chemistry, Inorganic & Nuclear
Bowen Zhang, Junwei Liu, Shenglin Lu, Xiaohui Yan, Wenbin Guo, Congling Yin, Xing Ming, Xiaojun Kuang
Summary: In this study, a disordered cubic phase of rocksalt-type Ti1-xMgxN was successfully synthesized using the conventional bulk synthesis method. The crystal structure and physical properties of the Ti1-xMgxN solid solution can be tuned by the Mg content, showing a metal-to-semiconductor transition and suppression of the superconducting phase transition. The results demonstrate the feasibility of the simple bulk route for the synthesis of Mg-containing ternary nitrides and the modulation of nitride properties through heterovalent ion substitution.
INORGANIC CHEMISTRY
(2023)
Article
Chemistry, Inorganic & Nuclear
Bowen Zhang, Junwei Liu, Shenglin Lu, Xiaohui Yan, Wenbin Guo, Congling Yin, Xing Ming, Xiaojun Kuang
Summary: In this study, rocksalt-type Ti1-xMgxN crystals were successfully synthesized by the conventional bulk synthesis method, and it was found that the crystal structure and physical properties of Ti1-xMgxN can be tuned by the Mg content. A metal-to-semiconductor transition and suppression of the superconducting phase transition were observed when the Mg and Ti content ratio approached 1. Theoretical calculations showed that lattice distortions induced by the different ionic sizes of Mg and Ti increased with the Mg content, and the disordered cubic rocksalt structures became unstable. Furthermore, electronic structure calculations provided insights into the low resistance behavior and transport property evolution of Ti1-xMgxN.
INORGANIC CHEMISTRY
(2023)
Article
Engineering, Electrical & Electronic
Tianchen Yang, Chengyun Shou, Long Xu, Jason Tran, Yanwei He, Yuan Li, Peng Wei, Jianlin Liu
Summary: In this study, deep-ultraviolet fi-MgGaO metal-semiconductor-metal photodetectors were fabricated and their responsivity was investigated. The results showed that these detectors have potential for deep-ultraviolet photodetection and other photonic device applications.
ACS APPLIED ELECTRONIC MATERIALS
(2023)
Article
Physics, Condensed Matter
Naoya Mokutani, Momoko Deura, Shinichiro Mouri, Kanako Shojiki, Shiyu Xiao, Hideto Miyake, Tsutomu Araki
Summary: Researchers have successfully fabricated GaN/AlN superlattices consisting of few-monolayer GaN wells with flat and abrupt interfaces by precise growth control. The superlattice structures are grown on face-to-face-annealed sputter-deposited AlN template substrates using radio-frequency plasma-excited molecular beam epitaxy (RF-MBE) and in situ reflection high-energy electron diffraction (RHEED) monitoring. AlN and GaN are grown under metal-rich conditions, and droplets are eliminated by the droplet elimination by radical beam irradiation (DERI) method for AlN and by growth interruption for GaN. The dependence of AlN thickness on superlattice properties is investigated, and it is found that the AlN thickness is easily controllable. A total of 20-period GaN/AlN superlattices with flat and abrupt interfaces is confirmed using atomic force microscopy and X-ray diffraction. Cathodoluminescence measurements show a peak wavelength of 230-260 nm at room temperature, which shifts with increasing AlN thickness.
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Jonatas Faleiro Berbigier, Renita M. M. D'Souza, Raymond N. N. Bennett, Timothy L. L. Kelly
Summary: Traditionally, metal-catalyzed cross-coupling reactions have been extensively used for the synthesis of conjugated polymers. However, these reactions require functionalized monomers, leading to increased complexity and length of the synthesis process. Moreover, some commonly used reagents are highly toxic and residual metal impurities can affect the polymer's optoelectronic properties. Therefore, there is a demand for metal-free approaches to conjugated polymer synthesis. In this study, the indophenine reaction was employed to polymerize thiophene and bifunctional isatin comonomers using sulfuric acid as the catalyst. The resulting polymers exhibited wide absorption bands, electrochromic behavior, and low optical bandgaps.
ACS APPLIED POLYMER MATERIALS
(2023)
Article
Nanoscience & Nanotechnology
MengQi Cui, Zhitao Shao, LiHang Qu, Xin Liu, Huan Yu, Yunxia Wang, Yunxiao Zhang, Zhendong Fu, Yuewu Huang, Wei Feng
Summary: This study explored the photoresponse of an indium oxide (In2O3)-based photoelectrochemical (PEC) ultraviolet photodetector (UV PD) for the first time. The results demonstrate that In2O3 has good UV photoresponse and stability, indicating great potential for application in high-performance PEC UV PDs.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Chemistry, Multidisciplinary
Soham Saha, Mustafa Goksu Ozlu, Sarah N. Chowdhury, Benjamin T. Diroll, Richard D. Schaller, Alexander Kildishev, Alexandra Boltasseva, Vladimir M. Shalaev
Summary: The unique properties of emerging photonic materials, conducting nitrides and oxides, are explored in this study. The optical properties of polycrystalline titanium nitride and aluminum-doped zinc oxide can be controlled by tailoring the film thickness. The study demonstrates their potential for ENZ-enhanced photonic applications, including optical circuitry, tunable metasurfaces, and nonlinear optical devices.
ADVANCED MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Alexandre C. Foucher, Jennifer D. Lee, Zhen Qi, Gengnan Li, Gaoyuan Ouyang, Jun Cui, Jorge Anibal Boscoboinik, Cynthia M. Friend, Juergen Biener, Eric A. Stach
Summary: The use of nanoporous metals as catalysts has attracted significant interest due to their high surface area and density of undercoordinated sites. However, their long-term stability is limited by thermal coarsening. This study demonstrates that the nanoscale morphology of nanoporous Cu can be regenerated by applying oxidation/reduction cycles at 250 degrees C.
ADVANCED ENGINEERING MATERIALS
(2023)
Article
Optics
Colton Fruhling, Kang Wang, Sarah Chowdhury, Xiaohui Xu, Jeffrey Simon, Alexander Kildishev, Letian Dou, Xiangeng Meng, Alexandra Boltasseva, Vladimir M. Shalaev
Summary: Coherent random lasing in subwavelength quasi-2D perovskite films is observed and studied. Statistical analysis reveals Levy-like intensity fluctuations, replica symmetry breaking confirms random lasing, and spectral and spatial correlation techniques are used to study coherent modes. The observed coherent lasing modes are extended states that result from the random crystal grain structure during fabrication and out-compete diffusive lasing due to their coherence.
LASER & PHOTONICS REVIEWS
(2023)
Article
Chemistry, Multidisciplinary
Xiaohui Xu, Abhishek B. Solanki, Demid Sychev, Xingyu Gao, Samuel Peana, Aleksandr S. Baburin, Karthik Pagadala, Zachariah O. Martin, Sarah N. Chowdhury, Yong P. Chen, Takashi Taniguchi, Kenji Watanabe, Ilya A. Rodionov, Alexander Kildishev, Tongcang Li, Pramey Upadhyaya, Alexandra Boltasseva, Vladimir M. Shalaev
Summary: The negatively charged boron vacancy defect in boron nitride has potential in quantum sensing, but its low quantum efficiency hampers its practical applications. This study demonstrates significantly higher emission enhancements of the defect using low-loss nanopatch antennas, making it a promising high-resolution magnetic field sensor.
Review
Optics
Soham Saha, Ohad Segal, Colton Fruhling, Eran Lustig, Mordecai Segev, Alexandra Boltasseva, Vladimir M. Shalaev
Summary: Recent advances in ultrafast, large-modulation photonic materials have led to the potential development of photonic time crystals. This perspective discusses the promising candidates for photonic time crystals, outlining their modulation speed and depth. The challenges and possible paths to success are also analyzed.
Review
Optics
Eran Lustig, Ohad Segal, Soham Saha, Colton Fruhling, Vladimir M. Shalaev, Lexandra Boltasseva, Mordechai Segev
Summary: Photonic Time-Crystals (PTCs) are materials with periodically and abruptly varying refractive index in time. This medium exhibits unique properties, such as momentum bands separated by gaps where waves can be exponentially amplified, extracting energy from the modulation. This article provides a brief review of PTC concepts, formulates the vision, and discusses the challenges.
Article
Physics, Applied
Yunfei He, Shangyi Chen, Merrilyn Mercy Adzo Fiagbenu, Chloe Leblanc, Pariasadat Musavigharavi, Gwangwoo Kim, Xingyu Du, Jiazheng Chen, Xiwen Liu, Eric A. Stach, Roy H. Olsson, Deep Jariwala
Summary: This letter presents the oriented growth and switching of thin ferroelectric aluminum scandium nitride (AlScN) films directly on degenerately doped 4H silicon carbide (SiC) wafers. The high-quality thin Al0.68Sc0.32N films on doped SiC substrates enable the monolithic integration of nonvolatile memory with SiC-based logic devices suitable for high temperature operation as well as high-power switching, memory, and sensing applications.
APPLIED PHYSICS LETTERS
(2023)
Article
Chemistry, Physical
Kai Shen, Jian Chang, Rajeev Kumar Rai, Ching-Yu Wang, Eric A. Stach, Raymond J. Gorte, John M. Vohs
Summary: The thermodynamic and structural properties of 1 nm thick films of CeVO4 and LaVO4 supported on & gamma;-Al2O3 were compared to the corresponding bulk rare-earth vanadates. The thin films exhibited different crystalline structures and equilibrium oxygen pressures compared to the bulk materials. Thin-film LaVO4 showed reversible transitions between perovskite and monazite structures, while thin-film CeVO4 showed reversible transitions between perovskite and fluorite structures. The reasons for these differences were discussed.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Chemistry, Inorganic & Nuclear
Kai Shen, Mengjie Fan, Rajeev Kumar Rai, Eric A. Stach, Raymond J. Gorte, John M. Vohs
Summary: Conformal thin films of CeMnOx were deposited on a gamma-Al2O3 support by ALD. The film showed reversible phase transition between reduced perovskite CeMnO3 and oxidized fluorite CeMnO3.5 during redox cycling. The oxidation states of Ce and Mn were determined by XPS and EELS, and the composition of the film under different P(O2) was measured by coulometric titration.
JOURNAL OF SOLID STATE CHEMISTRY
(2023)
Article
Materials Science, Multidisciplinary
Hyeongjun Koh, Eric Detsi, Eric A. Stach
Summary: Understanding the nanoscale structure and chemistry of energy storage materials is crucial for battery performance, but characterizing them at high resolution can be challenging due to sample preparation methods. In this study, we used cryogenic lift-out technique to prepare air-sensitive lithium metal and investigated ion-beam damage during sample preparation. Through cryogenic transmission electron microscopy, we found that lithium was not damaged by ion-beam milling, but formed lithium oxide shells in the PFIB/SEM chamber. Cryogenic energy loss spectroscopy confirmed the oxidation of lithium during sample preparation. Our results highlight the importance of understanding how cryogenic lift-out sample preparation affects the high-resolution characterization of reactive battery materials.
MICROSCOPY AND MICROANALYSIS
(2023)
Article
Multidisciplinary Sciences
Zhaxylyk A. Kudyshev, Demid Sychev, Zachariah Martin, Omer Yesilyurt, Simeon I. Bogdanov, Xiaohui Xu, Pei-Gang Chen, Alexander V. Kildishev, Alexandra Boltasseva, Vladimir M. Shalaev
Summary: One of the main characteristics of optical imaging systems is spatial resolution, which is restricted by the diffraction limit. Recently, classical and quantum super-resolution techniques have been developed to break the diffraction limit. We propose a machine learning-assisted approach for rapid antibunching super-resolution imaging, achieving a 12 times speed-up compared to conventional methods. This framework enables the practical realization of scalable quantum super-resolution imaging devices compatible with various quantum emitters.
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Brandon C. Vance, Sean Najmi, Pavel A. Kots, Cong Wang, Sungho Jeon, Eric A. Stach, Dmitri N. Zakharov, Nebojsa Marinkovic, Steven N. Ehrlich, Lu Ma, Dionisios G. Vlachos
Summary: Earth-abundant metals have been proven as cost-effective catalysts for polyethylene hydrogenolysis, replacing scarce noble metals. However, the high selectivity for methane production poses challenges for industrial application. In this study, it is demonstrated that ex-situ reduction of coprecipitated nickel aluminate catalysts at low temperatures (350°C) yields a methaneselectivity of less than 5%. Increasing the reduction temperature to 550°C results in a sevenfold increase in methane selectivity. The characterization of the catalyst and the reaction process reveals the role of Ni nanoparticles and Ni2+ cations in methane production. The discovered structure-methane selectivity relationship provides guidance for the design of Ni-based catalysts with low methane generation and paves the way for further understanding of structure-property relationships in plastics hydrogenolysis. These catalysts are also effective for polypropylene hydrogenolysis.
Article
Nanoscience & Nanotechnology
Eran Lustig, Ohad Segal, Soham Saha, Eliyahu Bordo, Sarah N. Chowdhury, Yonatan Sharabi, Avner Fleischer, Alexandra Boltasseva, Oren Cohen, Vladimir M. Shalaev, Mordechai Segev
Summary: We experimentally study optical time-refraction caused by time-interfaces as short as a single optical cycle. By observing the propagation of a probe pulse through a sample with a large refractive index change induced by an intense modulator pulse, we find that increasing the refractive index abruptly leads to red-shifted waves while decreasing it back to the original value causes a subsequent blue-shift. Shortening the temporal width of the modulator pulse leads to a proportionally shorter rise time of the red-shift associated with time-refraction. These experiments are conducted in transparent conducting oxides acting as epsilon-near-zero materials. The findings stimulate questions about the fundamental physics in ultrashort time frames and pave the way for future experiments with photonic time-crystals generated by periodic refractive index changes.
Article
Chemistry, Physical
Xiaoman Zhang, Eric A. Stach, W. J. Meng, Andrew C. Meng
Summary: In this study, epitaxial wurtzite AlScN thin films were grown on Si (111) substrates by ultra-high vacuum reactive sputtering. Sc alloying in AlN enhances piezoelectricity and induces ferroelectricity, making epitaxial thin films suitable for systematic investigations of these materials. Increasing Sc concentration leads to crystalline disorder and a structural transition from wurtzite to rocksalt, as well as nanoscale compositional segregation consistent with spinodal decomposition. The observed composition fluctuations are correlated with polarization domains, suggesting an influence on ferroelectric properties. These results provide a route for creating single crystal AlScN films and self-assembled composition modulation.
NANOSCALE HORIZONS
(2023)
Article
Chemistry, Multidisciplinary
Yikang Yu, Hyeongjun Koh, Zisheng Zhang, Zhenzhen Yang, Anastassia N. Alexandrova, Mangilal Agarwal, Eric A. Stach, Jian Xie
Summary: The study challenges the traditional understanding of lithium ion transport in the solid electrolyte interphase (SEI) and proposes a new mechanism of one-step pore diffusion. The results suggest that the influence of SEI structure on lithium ion transport kinetics is less significant than previously believed. This finding has potential implications for the design of fast-charging battery materials.
ENERGY & ENVIRONMENTAL SCIENCE
(2023)
