Article
Multidisciplinary Sciences
Thomas McJunkin, Benjamin Harpt, Yi Feng, Merritt P. Losert, Rajib Rahman, J. P. Dodson, M. A. Wolfe, D. E. Savage, M. G. Lagally, S. N. Coppersmith, Mark Friesen, Robert Joynt, M. A. Eriksson
Summary: This study proposes a new heterostructure, the Wiggle Well, which uses concentration oscillations of Ge in the quantum well to enhance the valley splitting of quantum-dot spin qubits. The experimental results show that the presence of Ge in the quantum well does not affect the formation and manipulation of single-electron quantum dots. It is suggested that the enhancement of the valley splitting is mainly attributed to random concentration fluctuations and the presence of Ge alloy.
NATURE COMMUNICATIONS
(2022)
Article
Materials Science, Multidisciplinary
Sara Conti, Samira Saberi-Pouya, Andrea Perali, Michele Virgilio, Francois M. Peeters, Alexander R. Hamilton, Giordano Scappucci, David Neilson
Summary: By confining holes in a compressively strained Germanium quantum well and electrons in a lattice-matched tensile strained Silicon quantum well in a lattice-matched strained Si/Ge bilayer embedded into a Germanium-rich SiGe crystal, observable mass-imbalanced electron-hole superfluidity and BEC can be achieved, potentially leading to superfluidity at experimentally accessible temperatures.
NPJ QUANTUM MATERIALS
(2021)
Proceedings Paper
Instruments & Instrumentation
Yi Zhang, Junqiang Sun
Summary: The Ge/SGe coupled quantum wells with uniaxial tensile strain can be tuned through the size and shape of the suspended region, resulting in enhanced absorption for TE polarization and decreased absorption for TM polarization. This proposed scheme opens the way for efficient silicon-based integrated devices.
OPTOELECTRONIC MATERIALS AND DEVICES (ICOMD 2020)
(2021)
Article
Nanoscience & Nanotechnology
Qimiao Chen, Liyao Zhang, Yuxin Song, Xiren Chen, Sebastian Koelling, Zhenpu Zhang, Yaoyao Li, Paul M. Koenraad, Jun Shao, Chuan Seng Tan, Shumin Wang, Qian Gong
Summary: Highly tensile-strained Ge quantum dots emitting structures with different sizes were successfully grown on InP substrates by molecular beam epitaxy. The photoluminescence from direct band-gap-like transitions of TS-Ge-QDs was achieved, and the band structure of the TS-Ge-QDs emitting structures was calculated to support the experimental results. These results provide encouraging evidence for the future photonics applications of this promising highly tensile strained semiconductor-nanostructure-based platform such as integrated light sources.
ACS APPLIED NANO MATERIALS
(2021)
Article
Nanoscience & Nanotechnology
Yi Zhang, Jianfeng Gao, Senbiao Qin, Ming Cheng, Kang Wang, Li Kai, Junqiang Sun
Summary: The study introduces an asymmetric Ge/SiGe coupled quantumwell (CQW) waveguide modulator for both intensity and phase modulation in silicon photonic integration. By controlling the coupling of the wave functions, the fabricated device achieves low energy consumption, high speed, and compact size.
Article
Engineering, Electrical & Electronic
Troy A. Hutchins-Delgado, Andrew J. Miller, Robin Scott, Ping Lu, Dwight R. Luhman, Tzu-Ming Lu
Summary: Hole spins in Ge quantum wells have shown success in spintronic and quantum applications. This study analyzed and characterized the material and devices of commercially grown Ge/SiGe quantum well heterostructures. The results confirmed the high quality of the material and demonstrated a high mobility hole gas. The study also investigated the use of surface preparations to control barrier thickness, density, mobility, and interface trap density.
ACS APPLIED ELECTRONIC MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
V. T. Dolgopolov, M. Yu Melnikov, A. A. Shashkin, S-H Huang, C. W. Liu, S. Kravchenko
Summary: In an ultraclean strongly interacting bivalley SiGe/Si/SiGe two-dimensional electron system, minima of longitudinal resistance corresponding to the quantum Hall effect of composite fermions are observed at different quantum numbers p = 1, 2, 3, 4, and 6. The disappearance of the minimum at p = 3 below a certain electron density, while the surrounding minima at p = 2 and p = 4 survive at significantly lower densities, suggests the intersection or merging of quantum levels of composite fermions with different valley indices, revealing the valley effect on fractions.
Article
Physics, Condensed Matter
N. Ajnef, M. M. Habchi, A. Rebey
Summary: The study systematically explored the optical properties of interband and intersubband transitions in GaNAsBi/GaAs quantum well heterostructure. The importance of the polarization mode in changing optical absorption magnitude was highlighted through theoretical optimization of physical parameters, indicating the potential for tuning photodetection spectra in future designed systems by controlling relevant parameters.
MICRO AND NANOSTRUCTURES
(2022)
Article
Materials Science, Multidisciplinary
Andrew J. Miller, Will J. Hardy, Dwight R. Luhman, Mitchell Brickson, Andrew Baczewski, Chia -You Liu, Jiun-Yun Li, Michael P. Lilly, Tzu-Ming Lu
Summary: Lithographic quantum dots in strained-Ge/SiGe have rapidly advanced from the realization of a single-hole quantum dot to multiqubit devices. This study presents a measurement of the out-of-plane g factor for a single-hole quantum dot in this material and validates the expected g-factor anisotropy.
Article
Materials Science, Multidisciplinary
Haochen Zhao, Guangyang Lin, Chaoya Han, Ryan Hickey, Tuofu Zhama, Peng Cui, Tienna Deroy, Xu Feng, Chaoying Ni, Yuping Zeng
Summary: In this work, the evolution of structural, optical, and optoelectronic properties of coherently strained Ge0.883Sn0.117/Ge multiple quantum wells (MQWs) grown by molecular beam epitaxy under rapid thermal annealing (RTA) is investigated. The MQW structure remains fully-strained state with RTA at 400°C or below and disrupts at higher annealing temperatures due to Sn segregation and interdiffusion of Ge and Sn atoms. The results provide guidance for the development of high-performance short-wave infrared photonic devices based on Sn-containing group-IV low-dimensional structures.
Article
Materials Science, Multidisciplinary
Benjamin D. Woods, M. A. Eriksson, Robert Joynt, Mark Friesen
Summary: We demonstrate that Ge concentration oscillations in the quantum well region of a Si/SiGe heterostructure can greatly enhance the spin-orbit coupling in the low-energy conduction-band valleys. This enhancement is attributed to Ge concentration oscillations generating wave-function satellite peaks in momentum space, which couple to the opposite valley through Dresselhaus spin-orbit coupling. The improved spin-orbit coupling enables fast spin manipulation in Si quantum dots using electric dipole spin resonance without the need for micro-magnets, with a Rabi frequency S2Rabi/B > 500 MHz/T near the optimal Ge oscillation wavelength lambda = 1.57 nm.
Article
Nanoscience & Nanotechnology
Worawat Traiwattanapong, Papichaya Chaisakul, Jacopo Frigerio, Daniel Chrastina, Giovanni Isella, Laurent Vivien, Delphine Marris-Morini
Summary: This study reports on the design and simulation of a waveguide-integrated Ge/SiGe quantum-confined Stark effect optical modulator, demonstrating through 3D finite-difference time domain simulation that a simple 2D taper enables efficient optical coupling between input SiGe waveguide and Ge/SiGe multiple quantum well modulator. The study also presents wideband optical modulation performance over the low-loss spectral range of Ge/SiGe MQWs, showing the potential for Si-based optical modulators.
Article
Chemistry, Physical
Xiangquan Liu, Jun Zheng, Qinxing Huang, Yaqing Pang, Diandian Zhang, Yupeng Zhu, Zhi Liu, Yuhua Zuo, Buwen Cheng
Summary: The GePb/Ge multiple quantum well (MQW) structures were successfully grown on Ge(100) substrates, and the band gap regulation caused by the quantum confinement effect was verified. The MQW structures exhibited high crystal quality and thermal stability, making them a promising approach for efficient GePb light sources.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Materials Science, Multidisciplinary
Qiang Luo, Jize Zhao, Xiaoqun Wang, Hae-Young Kee
Summary: Understanding the interplay of Kitaev and Gamma interactions is key to unraveling intriguing phenomena in various Kitaev materials. A study of the quantum phase diagram of a bond-alternating spin-1/2 g(x)-g(y) K-Gamma chain reveals phases dominated by even-Haldane, odd-Haldane, gapped A(x) and A(y) phases near the antiferromagnetic Kitaev limit, and symmetric-breaking magnetic phases. The isotropic ferromagnetic Kitaev point serves as a multicritical point where two topological phase transitions meet.
Article
Physics, Applied
M. Lodari, O. Kong, M. Rendell, A. Tosato, A. Sammak, M. Veldhorst, A. R. Hamilton, G. Scappucci
Summary: A lightly strained germanium channel supports a high-mobility two-dimensional hole gas with low percolation density. This low-disorder system exhibits tunable fractional quantum Hall effects at low densities and low magnetic fields, making it a promising platform for fast and coherent quantum hardware.
APPLIED PHYSICS LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Andrea De Iacovo, Federica Mitri, Andrea Ballabio, Jacopo Frigerio, Giovanni Isella, Andrea Ria, Mattia Cicalini, Paolo Bruschi, Lorenzo Colace
Summary: This paper demonstrates the operation of a Ge-on-Si multipixel array and verifies its imaging capabilities through an experiment. The research findings are of great significance for the development of integrated imaging systems.
IEEE SENSORS JOURNAL
(2022)
Article
Materials Science, Multidisciplinary
Giulio Tavani, Andrea Chiappini, Alexey Fedorov, Francesco Scotognella, Stefano Sanguinetti, Daniel Chrastina, Monica Bollani
Summary: In this article, the authors report the development of oxidation processes to fully convert AlAs to AlOx films for vertical optical confinement in III-V photonic devices. The authors demonstrate the selectivity of the AlAs oxidation process and highlight the potential of this approach for nonlinear photonic applications in III-V photonic crystal devices.
OPTICAL MATERIALS EXPRESS
(2022)
Article
Nanoscience & Nanotechnology
Miguel Montesinos-Ballester, Lucas Deniel, Natnicha Koompai, Thi Hao Nhi Nguyen, Jacopo Frigerio, Andrea Ballabio, Virginia Falcone, Xavier Le Roux, Carlos Alonso-Ramos, Laurent Vivien, Adel Bousseksou, Giovanni Isella, Delphine Marris-Morini
Summary: Mid-infrared spectroscopy is crucial for identifying molecular species, and integrated modulators are expected to have a significant impact in sensing applications. This work demonstrates a broadband integrated electro-optic modulator, paving the way for the development of multi-molecular on-chip spectroscopic systems operating at the longest mid-infrared wavelengths.
Article
Physics, Multidisciplinary
Daniel Jirovec, Philipp M. Mutter, Andrea Hofmann, Alessandro Crippa, Marek Rychetsky, David L. Craig, Josip Kukucka, Frederico Martins, Andrea Ballabio, Natalia Ares, Daniel Chrastina, Giovanni Isella, Guido Burkard, Georgios Katsaros
Summary: In this study, we investigate the effect of the cubic Rashba spin-orbit interaction on the mixing of spin states in a planar Ge hole double quantum dot. Our results show that the spin-flip term induced by the spin-orbit interaction has a significant impact on the spin state mixing. This finding is important for optimizing future qubit experiments.
PHYSICAL REVIEW LETTERS
(2022)
Article
Computer Science, Interdisciplinary Applications
Dou Du, Taylor J. Baird, Sara Bonella, Giovanni Pizzi
Summary: This paper introduces the OSSCAR platform, which provides an open collaborative environment for students and researchers to develop and access educational resources. By combining standard software tools with custom domain-specific ones, OSSCAR aims to minimize the efforts in creating and using new educational material. Examples from courses in physics, chemistry, and materials science are shown to demonstrate the interactivity and style of OSSCAR. The tools presented are easy to use and create a uniform and open environment exploitable by a large community.
COMPUTER PHYSICS COMMUNICATIONS
(2023)
Article
Crystallography
Artur Tuktamyshev, Stefano Vichi, Federico Cesura, Alexey Fedorov, Sergio Bietti, Daniel Chrastina, Shiro Tsukamoto, Stefano Sanguinetti
Summary: By precisely controlling the growth kinetics, we have achieved the growth of flat InAlAs metamorphic buffer layers on 2 degrees -off GaAs(111)A substrates using molecular beam epitaxy. Almost full plastic relaxation is obtained for a layer thickness > 40 nm, and the root-mean-square surface roughness of the InAlAs epilayer is reduced to 0.55 nm through the control of adatom diffusion length and step ejection probability.
JOURNAL OF CRYSTAL GROWTH
(2022)
Article
Chemistry, Multidisciplinary
Mani Azadmand, Stefano Vichi, Federico Guido Cesura, Sergio Bietti, Daniel Chrastina, Emiliano Bonera, Giovanni Maria Vanacore, Shiro Tsukamoto, Stefano Sanguinetti
Summary: The influence of metal droplets on the composition uniformity of InGaN epilayers was investigated. Experimental and theoretical analysis revealed a significant difference in indium incorporation between the region under the droplets and between them.
Article
Nanoscience & Nanotechnology
C. Zucchetti, F. Scali, P. Grassi, M. Bollani, L. Anzi, G. Isella, M. Finazzi, F. Ciccacci, F. Bottegoni
Summary: We have developed a non-local architecture for spin current injection, manipulation, and detection in n-doped bulk Si at room temperature. Spins are generated by circularly polarized light at the indirect gap of bulk Si and detected using the inverse spin-Hall effect in a thin Pt pad deposited on the Si substrate. By applying a bias voltage, we can modulate the transport properties of the injected spin current, exploring both the spin diffusion and drift regimes.
Article
Chemistry, Multidisciplinary
Davide Campi, Nicolas Mounet, Marco Gibertini, Giovanni Pizzi, Nicola Marzari
Summary: Two-dimensional (2D) materials are highly promising candidates foradvanced electronic, optoelectronic, and quantum computing applicationsbeyond silicon. In recent years, there has been a significant effortto discover and characterize novel 2D materials, resulting in a rapidincrease in the number of experimentally exfoliated or synthesized2D materials. This study reports a major expansion of the 2D materialportfolio, with the discovery of 1252 new monolayers, bringing thetotal number to 3077 compounds. The electronic and structural propertiessuch as bandgap and lattice strain of these materials are analyzed,with a focus on large-bandgap 2D materials suitable for field-effecttransistor channels. Additionally, the best candidates for formingcommensurate heterostructures are identified for each material containingup to 6 atoms per unit cell.
Article
Physics, Applied
Victor Ukleev, Max Burian, Sebastian Gliga, C. A. F. Vaz, Benedikt Rosner, Danny Fainozzi, Gediminas Seniutinas, Adam Kubec, Roman Mankowsky, Henrik T. Lemke, Ethan R. Rosenberg, Caroline A. Ross, Elisabeth Mueller, Christian David, Cristian Svetina, Urs Staub
Summary: Magnetic domain patterns in Tm-doped yttrium iron garnet (Tm:YIG) thin film can be locally imprinted by high intensity photon pulses of a hard x-ray transient grating (XTG). Micromagnetic simulations provide an understanding of the observed changes in magnetic domains orientation in Tm:YIG and XTG-induced changes. These results offer a route for the local manipulation of the magnetic state using hard XTG.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Multidisciplinary Sciences
Salvatore De Angelis, Tobias Schuler, Mayank Sabharwal, Mirko Holler, Manuel Guizar-Sicairos, Elisabeth Mueller, Felix N. Buechi
Summary: Reducing precious metal loading in the anodic catalyst layer is crucial for cost reduction and wider adoption of polymer electrolyte water electrolysis. This study presents the first 3D reconstruction of a TiO2-supported IrO2 core shell catalyst layer, revealing the nanoporous structure of IrO2 shells and the non-uniform thickness of the ionomer. The analysis of conductivity shows that the ionic conductivity is significantly lower than the electronic conductivity in a dry catalyst layer.
SCIENTIFIC REPORTS
(2023)
Article
Chemistry, Physical
Miki Bonacci, Junfeng Qiao, Nicola Spallanzani, Antimo Marrazzo, Giovanni Pizzi, Elisa Molinari, Daniele Varsano, Andrea Ferretti, Deborah Prezzi
Summary: In this work, algorithms and implementations were proposed to automate many-body perturbation theory (MBPT) calculations beyond density functional theory (DFT). An algorithm for efficient and robust convergence of GW and BSE simulations, along with its implementation in a fully automated framework, was provided. Additionally, an automatic GW band interpolation scheme based on maximally localized Wannier functions was introduced to reduce the computational burden of quasiparticle band structures while maintaining high accuracy. These developments were validated on representative semiconductor and metallic systems.
NPJ COMPUTATIONAL MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Leonardo V. S. Franca, Elisabeth Muller, Eduardo G. G. Yukihara, Oswaldo Baffa
Summary: This article reports the luminescent and dosimetric properties of a radiation sensitive phosphor based on CaB6O10:Tb3+,Ag+ compounds. The phosphor exhibited strong UV-OSL under blue stimulation, with a minimum detectable dose of 2.3 mu Gy. It also showed dose linearity in the whole dose range analyzed and no signs of saturation. The study also sheds light on how lanthanide and silver ions influence the charge trapping and radiative processes in borate compounds.
JOURNAL OF MATERIALS CHEMISTRY C
(2023)
Article
Materials Science, Multidisciplinary
Monika Vogler, Jonas Busk, Hamidreza Hajiyani, Peter Bjorn Jorgensen, Nehzat Safaei, Ivano E. Castelli, Francisco Fernando Ramirez, Johan Carlsson, Giovanni Pizzi, Simon Clark, Felix Hanke, Arghya Bhowmik, Helge S. Stein
Summary: Efficient utilization of resources is crucial for accelerated materials science research. Through modular and asynchronous orchestration, we have successfully integrated multiple laboratories on a cooperative multitenancy platform. This represents the first internationally distributed materials acceleration platform connected via a passive brokering server.
Article
Chemistry, Physical
G. M. Vanacore, D. Chrastina, E. Scalise, L. Barbisan, A. Ballabio, M. Mauceri, F. La Via, G. Capitani, D. Crippa, A. Marzegalli, R. Bergamaschini, L. Miglio
Summary: This paper addresses the unique nature of fully textured, high surface-to-volume 3C-SiC films, produced by intrinsic growth anisotropy. The structural interpretation of scanning electron microscopy and transmission electron microscopy data is carried out for samples grown under suitable deposition conditions. Twinning along (111) planes is also found to be frequent in such materials.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
