Article
Engineering, Electrical & Electronic
Okan Yurduseven, Choonsup Lee, David Gonzalez-Ovejero, Mauro Ettorre, Ronan Sauleau, Goutam Chattopadhyay, Vincent Fusco, Nacer Chahat
Summary: The silicon-gallium arsenide semiconductor-based holographic metasurface antenna can operate at 94 GHz, using holographic approach to modulate guided-mode generated by a pillbox beamformer with three independent beams for beam steering. The antenna is planar and extremely low-profile, suitable for small platforms.
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION
(2021)
Article
Materials Science, Multidisciplinary
Ayoub Zumeit, Abhishek Singh Dahiya, Adamos Christou, Rudra Mukherjee, Ravinder Dahiya
Summary: This study presents a printing technique to fabricate high-performance flexible broadband photodetectors on flexible substrates. The detectors demonstrate fast response and recovery times, high responsivity and detectivity, and stable performance under mechanical bending and twisting.
ADVANCED MATERIALS TECHNOLOGIES
(2022)
Article
Chemistry, Multidisciplinary
Ara Ghukasyan, Nebile Isik Goktas, Vladimir G. Dubrovskii, Ray R. LaPierre
Summary: Transmission electron microscopy was used to investigate the formation of TSLs in Te-doped GaAs nanowires grown by selective-area molecular beam epitaxy, revealing periodic TSLs only at low V/III flux ratio and intermediate growth temperatures. These results were explained by a kinetic growth model based on diffusion flux feeding the Ga droplet.
Article
Nanoscience & Nanotechnology
Geun Won Gang, Jong Hoon Lee, Su Yeon Kim, Taehyeon Jeong, Kyung Bin Kim, Nguyen Thi Hong Men, Yu Ra Kim, Sang Jung Ahn, Chung Soo Kim, Young Heon Kim
Summary: In situ heating transmission electron microscopy was used to study the microstructural evolutions in self-catalyzed GaAs nanowires, showing morphological changes and atomic behavior at the interface. The process began at around 200 degrees C with formation and destruction of atomic layers, leading to Ga droplet depletion and rapid growth of zinc-blende GaAs structures above 300 degrees C. GaAs decomposition was observed at around 600 degrees C.
Article
Engineering, Electrical & Electronic
Daniel M. Fleetwood, Andrew O'Hara, Theresa Stellwag Mayer, Michael R. Melloch, Sokrates T. Pantelides
Summary: The significant increase in thermal carrier generation rates in MBE-grown p-i-n-i-p GaAs structures is attributed to deactivation of hydrogen-defect/impurity complexes during high-intensity, low-energy electron-beam irradiation. Quantum calculations suggest that deactivation of oxygen impurities is likely the cause of this degradation, with electric-field and excess-carrier-induced dehydrogenation of O-As-H complexes identified as a likely rate-limiting process.
IEEE TRANSACTIONS ON NUCLEAR SCIENCE
(2021)
Article
Engineering, Electrical & Electronic
Jingwen Wu, Tingting Yuan, Jianjun Liu, Jianyuan Qin, Zhi Hong, Jiusheng Li, Yong Du
Summary: This article presents an ultra-high sensitive refractive index metamaterial sensor within the terahertz region. The sensor structure consists of GaAs on the top, aluminum in the middle, and a polyimide as the bottom substrate. The sensor shows high sensitivity to changes in the refractive index and has adjustable absorption peak properties. The proposed sensor has potential applications in biomedical sensing, disease diagnosis, and trace detection of hazardous substances.
IEEE SENSORS JOURNAL
(2022)
Article
Crystallography
Edward Muzar, James A. H. Stotz
Summary: This article presents a new structure of a phononic crystal waveguide that gradually increases in width and is capable of waveguiding underneath a micro-structured surface. The optimum waveguide width can be determined by selecting appropriate parameters.
Article
Computer Science, Information Systems
Qin Zhang, Wei Shi, Cheng Ma, Lei Yang
Summary: This study successfully triggered a 3 mm gap GaAs photoconductive semiconductor switch (GaAs PCSS) using pulsed spark discharge. The GaAs PCSS exhibited a typical linear mode at a low bias voltage, with an on-state current waveform similar to an optical pulse. When biased at 4 kV, the switch entered a nonlinear mode, with a peak current of 33 A and a carriers' multiplication rate of 179. This study indicates that pulsed spark discharge is a promising candidate light source for direct triggering of GaAs PCSSs.
Article
Chemistry, Physical
Hansung Kim, In Won Yeu, Gyuseung Han, Gunwu Ju, Yun Joong Lee, Young-hun Shin, Jung-Hae Choi, Hyun Cheol Koo, Hyung-jun Kim
Summary: The study found that the evolution of surface morphology and underlying pyramidal defects in homoepitaxial GaAs (110) layers is closely related to the layer thickness and growth temperature, resulting in the formation of different shapes of three-dimensional surface islands, including triangular islands and starfish shapes.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Materials Science, Multidisciplinary
Jakub Jasinski, Akshay Balgarkashi, Valerio Piazza, Didem Dede, Alessandro Surrente, Michal Baranowski, Duncan K. Maude, Mitali Banerjee, Riccardo Frisenda, Andres Castellanos-Gomez, Anna Fontcuberta i Morral, Paulina Plochocka
Summary: Strain is a commonly used tool to tune optoelectronic properties, especially for TMDs. This paper presents a novel approach to induce strain in MoS2 monolayers using homoepitaxially grown GaAs nanomembranes, which allows for the integration of TMDs with III-V semiconductor nanostructures. The strain lifts the degeneracy of exciton states, resulting in linearly polarized emission with the polarization axis determined by the orientation of the nanomembranes.
Article
Nanoscience & Nanotechnology
Tuomas Haggren, Vidur Raj, Anne Haggren, Nikita Gagrani, Chennupati Jagadish, Hoe Tan
Summary: This report demonstrates the construction of a hole-selective III-V semiconductor solar cell on i-GaAs using copper iodide (CuI) and optimization of the GaAs surface passivation and oxygen content of CuI, leading to high open-circuit voltage and solar conversion efficiency.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Chemistry, Physical
Motoi Hirayama, Sho Kishigami, Takumi Goto, Shiro Tsukamoto
Summary: The Mn substitution reaction on GaAs(110) surface, observed in experiments, has been confirmed by first-principles pseudopotential calculations based on the spin density functional theory. The adsorption energy, substitution energy, desorption energy, and migration energies were evaluated, and energy changes in each process were examined in detail. It was found that the adsorption and substitution processes occur with a decrease in total energy. However, it is believed that the released Ga atoms from the substitution reaction migrate on the surface due to their high desorption energy. Furthermore, it was found that the spin densities of the adsorbed Ga on the GaAs(110) surface distribute parallel to the surface, and the most stable adsorption position of Ga is slightly away from the Mn site due to magnetic interaction with the topmost surface Mn.
Article
Chemistry, Multidisciplinary
Sahil Sharma, Carlos A. Favela, Bo Yu, Eduard Galstyan, Sicong Sun, Tanguy Terlier, Venkat Selvamanickam
Summary: This study presents a method for the heteroepitaxial growth of independent semiconductor films on commercial GaAs wafers by depositing fluoride layers and subsequently growing GaAs using MOCVD. The triple fluoride layers enable the liftoff of free-standing semiconductor films, which can be further transferred to desired substrates. The findings have significant implications in the development of high-performance, flexible, and large-area electronics.
ADVANCED MATERIALS INTERFACES
(2022)
Article
Materials Science, Ceramics
Dong Kangjia, Jiang Chen, Ren Shaobin, Lang Xiaohu, Gao Rui, Ye Hui
Summary: The anisotropy of mechanical property of gallium arsenide was calculated in this study, showing that the difference of structural parameters between planes is the main reason. The hardness and fracture toughness of GaAs exhibit varying degrees of changes with crystal orientation.
JOURNAL OF INORGANIC MATERIALS
(2021)
Article
Materials Science, Multidisciplinary
Marie-Leonor Touraton, Mickael Martin, Sylvain David, Nicolas Bernier, Nevine Rochat, Jeremy Moeyaert, Virginie Loup, Frederic Boeuf, Christophe Jany, Didier Dutartre, Thierry Baron
Summary: The study focused on metal organic chemical vapor deposition of AlGaAs on GaAs using selective epitaxial growth. It examined the growth and structural characteristics of AlGaAs layers on GaAs structures, and found that the selective growth of AlGaAs structures for red optical emission requires careful temperature tuning. The obtained layers are seen as excellent candidates for future red optical emitters directly integrated on a silicon wafer platform.
Article
Engineering, Electrical & Electronic
G. V. Colibaba, D. Rusnac, N. Costriucova, O. Shikimaka, E. V. Monaico
Summary: A new technological approach for sintering Al-doped ZnO ceramics has been developed using chemical vapor transport (CVT) based on HCl. This approach offers advantages such as low sintering temperature, absence of diameter deviation, and excess Zn presence. The influence of dopant powder, Al concentration, and stoichiometric deviation on the density and conductive properties of ceramics has been investigated.
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
(2023)
Article
Materials Science, Multidisciplinary
Kangfa Deng, Qihao Zhang, Yangxi Fu, Andres Fabian Lasagni, Heiko Reith, Kornelius Nielsch
Summary: This article presents a novel fabrication technique named PowderMEMS for high-performance, low-cost TE films and micro-patterns. The TE film is composed of agglomerated micro-sized N-type Bi2Te2.5Se0.5 powders with a molten binder of bismuth (Bi). The influence of key process parameters on TE performance is investigated, and the TE film exhibits a maximum power factor of 1.7 mW m-1K-2 at room temperature, the highest value reported so far.
ADVANCED ENGINEERING MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Eduard V. Monaico, Elena I. Monaico, Veaceslav V. Ursaki, Ion M. Tiginyanu
Summary: This study demonstrates the morphologies and topologies produced by anodization in binary semiconductor compounds with different bandgaps and crystallographic orientations, focusing on the technological procedures for generating controlled design arrays of pores. The mechanism of pore growth under the photoresist masks is discussed, as well as the connection between mask design and the architecture of the resulting porous structure. The study also investigates the evolution of physical characteristics resulting from anodization and briefly discusses potential practical applications of the proposed technological approaches and porous structures.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2023)
Article
Chemistry, Physical
Ruben Bueno Villoro, Duncan Zavanelli, Chanwon Jung, Dominique Alexander Mattlat, Raana Hatami Naderloo, Nicolas Perez, Kornelius Nielsch, Gerald Jeffrey Snyder, Christina Scheu, Ran He, Siyuan Zhang
Summary: By using scanning transmission electron microscopy and atom probe tomography, this study revealed the structural differences of hexagonal close-packed lattice phases at grain boundaries in Ti-doped NbFeSb half-Heusler compounds. It was found that the enrichment of Fe leads to high electrical resistivity in Nb0.95Ti0.05FeSb, while the accumulation of Ti dopants results in good electrical conductivity in Nb0.80Ti0.20FeSb. This resistive to conductive grain boundary phase transition provides a new design space for decoupling the intertwined electronic and phononic transport in thermoelectric materials.
ADVANCED ENERGY MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Klara Luenser, Andreas Undisz, Kornelius Nielsch, Sebastian Faehler
Summary: Understanding and optimizing the martensitic microstructure of nickel-titanium (NiTi) thin films is important for their applications in microsystems. Epitaxial films grown on single-crystalline substrates provide a model system to study the microstructure and exploit the anisotropic mechanical properties of NiTi. By analyzing the growth of NiTi on MgO(100) and Al2O3(0001), we achieve epitaxial films with desired orientations and demonstrate the effect of buffer layers on crystal quality and transformation behavior. Transmission electron microscopy confirms the presence of a martensitic microstructure with Guinier Preston-zone precipitates. This study provides valuable insights into the development of NiTi thin films with optimized properties.
JOURNAL OF PHYSICS-MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Satyakam Kar, Kornelius Nielsch, Sebastian Faehler, Heiko Reith
Summary: This article investigates different etching techniques for the microfabrication of magnetic shape memory alloys, compares their advantages and disadvantages, and proposes methods to overcome challenges. The results show that wet chemical etching is suitable for large structures, while ion beam etching is suitable for small structures. Finally, a microfabrication process using Si microtechnology to fabricate partially freestanding structures is demonstrated.
ADVANCED ENGINEERING MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Lukas Fink, Satyakam Kar, Klara Luenser, Kornelius Nielsch, Heiko Reith, Sebastian Faehler
Summary: Magnetic shape memory alloys have multifunctional properties and can be used for high stroke actuation, magnetocaloric refrigeration, and thermomagnetic energy harvesting. This study demonstrates the epitaxial growth of Ni-Mn-based Heusler alloys with single crystal-like properties on silicon substrates using a SrTiO3 buffer. It shows that standard microfabrication technologies can be used to prepare partly freestanding patterns. The approach is versatile and can be applied to NiTi shape memory alloys as well as spintronic and thermoelectric Heusler alloys, paving the way for integrating additional multifunctional effects into state-of-the-art microelectronic and micromechanical technology based on silicon.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Physics, Multidisciplinary
Eduard V. Monaico, Veaceslav V. Ursaki, Ion M. Tiginyanu
Summary: This paper discusses three different types of microstructures as substrates for electrochemical deposition of Au nanodots. The uniform deposition of Au nanodots with controlled density was successfully achieved by adjusting adjustable parameters, and the morphology of the produced hybrid microarchitectures was investigated using scanning electron microscopy. These microstructures are proposed as platforms for the development of complex 3D hybrid micro-nano-architectures with Au nanodots as catalysts.
EUROPEAN PHYSICAL JOURNAL PLUS
(2023)
Article
Chemistry, Physical
Jonas Wawra, Kornelius Nielsch, Ruben Huehne
Summary: Substrate-induced strains can significantly affect the structural and functional properties of epitaxial thin films. By growing epitaxial Ba0.7Sr0.3TiO3 films on REScO3 substrates with smaller lattice mismatch, the quality of the films was improved compared to SrTiO3. The strain state of the functional layer depended on the substrate and thickness, leading to differences in permittivity and polarization behavior at different temperatures.
Article
Physics, Multidisciplinary
V. V. Ursaki, S. Lehmann, V. V. Zalamai, V Morari, K. Nielsch, I. M. Tiginyanu, E. Monaico
Summary: Planar and core-shell structures were prepared using atomic layer deposition on semiconductor substrates. The morphology and luminescence properties of these structures were compared to those of coaxial core-shell structures obtained by coating GaAs nanowires with ZnO and TiO2 shells. The prepared structures were characterized using scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction analysis, and photoluminescence spectroscopy. The polarization characteristics of different recombination channels in the core-shell structures were investigated and analyzed based on factors such as contrast in dielectric constants, selection rules associated with crystal structure symmetry, and local strain related to specific microscopic structure.
ROMANIAN JOURNAL OF PHYSICS
(2023)
