Article
Chemistry, Multidisciplinary
Anna Roslawska, Pablo Merino, Christopher C. Leon, Abhishek Grewal, Markus Etzkorn, Klaus Kuhnke, Klaus Kern
Summary: Researchers have successfully addressed and characterized light sources on the scale of single molecules using scanning tunneling microscopy-induced luminescence (STML), achieving high-resolution observation of the dynamics of single molecule emission. They observed that single electron capture occurs in the low-nanosecond regime, while scanning of the tip affects the energy landscape for charge injection into the defect. The measurement principle can be extended to fundamental processes beyond charge transfer, such as exciton diffusion.
Article
Chemistry, Physical
Xubo Lai, Boyang Liu, Yuhang Wang, Liuwan Zhang
Summary: The resistive switching behavior of the spinel multiferroic CoCr2O4 film was investigated using in-situ scanning probe microscope in different atmosphere. The film showed nearly identical RS behavior in both vacuum and oxygen rich atmosphere, attributed to the charge trapping/detrapping process near the film surface. This stable RS effect suggests potential important applications in complex environment.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Optics
Yuqing Li, Jijun Zou, Yijun Zhang, Xincun Peng, Wenjuan Deng
Summary: In this study, a cesium/oxygen activation experiment was conducted on a gallium-arsenide-based electron-injection cathode in an ultra-high vacuum system. The residual impurities on the cathode surface and the thin emitter layer were found to result in a low cathode emission capacity and quantum efficiency.
OPTICS COMMUNICATIONS
(2022)
Article
Materials Science, Ceramics
Thomas J. Moran, Keigo Suzuki, Tadasu Hosokura, Alexander Khaetskii, Bryan D. Huey
Summary: By using atomic force microscopy to characterize discharging dynamics, researchers have found that microstructures in insulating materials can significantly affect discharging rates. This provides insight into optimizing microstructures for improved capacitor performance.
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
(2021)
Article
Chemistry, Multidisciplinary
Linghao Yan, Orlando J. Silveira, Benjamin Alldritt, Ondrej Krejci, Adam S. Foster, Peter Liljeroth
Summary: The successful fabrication of a 2D monolayer Cu-dicyanoanthracene MOF on an epitaxial graphene surface with long-range order and the study of its structural and electronic properties using low-temperature scanning tunneling microscopy and spectroscopy, along with density-functional theory calculations, show promise for future applications in electronic devices. The ability to access multiple molecular charge states in the 2D MOF using tip-induced local electric fields suggests potential for fabricating and characterizing 2D MOFs with engineered electronic states.
ADVANCED FUNCTIONAL MATERIALS
(2021)
Article
Meteorology & Atmospheric Sciences
W. P. Winn, J. J. Trueblood, K. B. Eack, H. E. Edens, E. M. Eastvedt, G. D. Aulich, S. J. Hunyady, M. E. Cwikla
Summary: When the electric field below a thunderstorm or other electrified cloud is around 10 kV/m, it is possible to trigger an upward-propagating lightning leader by launching a rocket that uncoils a wire from the ground. The triggered leader propagates upward from the tip of the wire lifted by the rocket, and when the channel is hot enough, a flash is visible. Triggering is common when the leader carries positive charge, but not when it carries negative charge.
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
(2021)
Article
Chemistry, Physical
Seokjun Cha, Yujang Cho, Jong Gyeong Kim, Hyeongsub Choi, Dahye Ahn, Jingzhe Sun, Dong-Soo Kang, Chanho Pak, Jong-Jin Park
Summary: In this study, the energy efficiency of triboelectric nanogenerators (TENGs) was maximized by utilizing high-voltage charge injection (HVCI) to increase surface charge densities. The experiment successfully increased the output voltage by 40 times and the output current by 1300 times using the gradient charge-confinement method. This study provides a simple and effective approach to enhance the performance of TENGs.
Article
Engineering, Electrical & Electronic
Mohammad Bani Shamseh, Ruben Inzunza, Tatsuaki Ambo
Summary: This article proposes a new active anti-islanding technique that can detect unintentional islands with high speed and reliability, without causing disturbance to the system in grid-connected mode.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2022)
Article
Nanoscience & Nanotechnology
Wilson Yeung-Sy Su, Ching Wang, Chih-Ting Chen, Bu-Wei Huang, Chun-Yi Li, Chii-Bin Wu, Jyh-Shyang Wang, Ji-Lin Shen, Kuan-Cheng Chiu
Summary: The time dependent photoconductivity spectra along the active InGaAs QW channel in a dual and symmetric Si delta-doped AlGaAs/InGaAs/AlGaAs QW structure were systematically studied under various conditions. Both positive and negative photoconductivity were observed, with the latter attributed to two different origins at different temperature and photon energy ranges.
Article
Materials Science, Composites
Liang Cao, Yinge Li, Chuanhui Cheng, Rui Xi, Chao Tang, Muneeb Ahmed, Jinghui Gao, Lisheng Zhong, George Chen
Summary: Investigating charge trap distribution characteristics of insulating materials is important for improving electrical properties, and this study focused on the surface potential decay processes of LDPE, LDPE/PS, XLPE-PS, and XLPE. The results showed that the featured structure in XLPE-PS composites reduced carrier mobility and deepened charge trap depth, without changing the width of charge trap energy distribution. Compared to XLPE, XLPE-PS exhibited a more consistent trap distribution under both positive and negative polarities, possibly due to the featured structure. These findings provide insights into the relationship between multi-phase structure and electrical insulation performance, and offer guidance for the design of insulating materials for HVDC cables.
COMPOSITES COMMUNICATIONS
(2023)
Correction
Materials Science, Multidisciplinary
Federico Chianese, Sandra Fusco, Mario Barra, Fabio Chiarella, Antonio Carella, Antonio Cassinese
Summary: The study investigated space-charge accumulation and band bending at conductive P3HT/PDIF-CN2 interfaces using scanning-Kelvin probe microscopy, providing valuable insights for researchers in this field.
JOURNAL OF MATERIALS CHEMISTRY C
(2021)
Article
Physics, Multidisciplinary
Shu-Fang Ma, Lei Li, Qing-Bo Kong, Yang Xu, Qing-Ming Liu, Shuai Zhang, Xi-Shu Zhang, Bin Han, Bo-Cang Qiu, Bing-She Xu, Xiao-Dong Hao
Summary: The segregation of In atoms in the InGaAs/AlGaAs interface and the suppression of segregation by a GaAs insertion layer are investigated using XRD, PL, and Cs-STEM techniques. The study provides direct evidence of In segregation and demonstrates the effectiveness of the GaAs layer in suppressing it on an atomic scale. These findings offer atomic-scale insights into the segregation behavior of In atoms and uncover the underlying mechanism of how the GaAs insertion layer improves the crystallinity, interface roughness, and optical performance of InGaAs/AlGaAs QWs.
Article
Chemistry, Multidisciplinary
Alessandro Grillo, Enver Faella, Aniello Pelella, Filippo Giubileo, Lida Ansari, Farzan Gity, Paul K. Hurley, Niall McEvoy, Antonio Di Bartolomeo
Summary: PtSe2 field-effect transistors exhibit p-type electrical conductivity sensitive to temperature and environmental pressure, with positive and negative photoconductivity coexisting under white light. Physisorbed oxygen molecules on the PtSe2 surface act as acceptors, affecting carrier concentration and optical properties through charge transfer mechanisms.
ADVANCED FUNCTIONAL MATERIALS
(2021)
Article
Physics, Multidisciplinary
Forest Shih-Sen Chien, Chun-Rung Huang, Chi-Yuan Lin, Kwai-Kong Ng
Summary: Contact electrification has the potential to convert mechanical energy to electrical energy, with charge transfer between the Fermi level of the metal and the neutral level of the surface states of the polymer playing a significant role. The process is described by a saturating exponential function and the charge transfer can cancel out the net bias, ultimately leading to the cessation of contact electrification.
CHINESE JOURNAL OF PHYSICS
(2021)
Article
Physics, Fluids & Plasmas
W. Han, N. Offeddu, T. Golfinopoulos, C. Theiler, C. K. Tsui, J. A. Boedo, E. S. Marmar
Summary: Recent experiments in tokamaks have shown that magnetically confined fusion plasmas with negative triangularity exhibit better confinement compared to those with positive triangularity. This improvement in confinement may be attributed to a reduction in fluctuations within the plasma core. Furthermore, measurements in the scrape-off layer (SOL) have revealed a strong reduction in fluctuation amplitudes in plasmas with negative triangularity, indicating almost complete suppression of plasma interaction with the main-chamber first-wall.
Article
Multidisciplinary Sciences
Wladislaw Michailow, Peter Spencer, Nikita W. Almond, Stephen J. Kindness, Robert Wallis, Thomas A. Mitchell, Riccardo Degl'Innocenti, Sergey A. Mikhailov, Harvey E. Beere, David A. Ritchie
Summary: The authors report a new phenomenon called the in-plane photoelectric effect, which exhibits a giant photoresponse at terahertz frequencies. This provides an opportunity for efficient direct detection across the entire terahertz range.
Article
Nanoscience & Nanotechnology
Andrea Barbiero, Jan Huwer, Joanna Skiba-Szymanska, David J. P. Ellis, R. Mark Stevenson, Tina Mueller, Ginny Shooter, Lucy E. Goff, David A. Ritchie, Andrew J. Shields
Summary: In this study, we embedded semiconductor quantum dots in hybrid circular Bragg gratings to efficiently generate nonclassical light. The fabrication of multiple devices with similar performance is crucial for their use as sources of single and entangled photons, and the ability to operate at telecom wavelength is essential for integration with existing fiber infrastructure.
Article
Multidisciplinary Sciences
Pedro M. T. Vianez, Yiqing Jin, Maria Moreno, Ankita S. Anirban, Anne Anthore, Wooi Kiat Tan, Jonathan P. Griffiths, Ian Farrer, David A. Ritchie, Andrew J. Schofield, Oleksandr Tsyplyatyev, Christopher J. B. Ford
Summary: This study investigates many-body modes in gated one-dimensional wires and observes two parabolic dispersions associated with spin and charge excitations at high energies. It also discovers two additional one-dimensional replica modes that strengthen with decreasing wire length.
Article
Physics, Applied
S. N. Holmes, J. Gough, C. Chen, D. A. Ritchie, M. Pepper
Summary: The study found that n-type doped InSb wafers can exhibit variable range hopping transport mechanism induced by Ga+ ion beam damage, with high damage levels showing three-dimensional behavior and lower doses displaying characteristics of Mott phonon-assisted VRH. Controlling the level of damage can alter the transport properties of the devices, allowing for the study of coherent transport processes in the hopping regime.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Alessandra Di Gaspare, Valentino Pistore, Elisa Riccardi, Eva A. A. Pogna, Harvey E. Beere, David A. Ritchie, Lianhe Li, Alexander Giles Davies, Edmund H. Linfield, Andrea C. Ferrari, Miriam S. Vitiello
Summary: This study demonstrates mode-locking in surface-emitting electrically pumped random quantum cascade lasers at terahertz frequencies by exploiting the giant third-order nonlinearity of semiconductor heterostructure lasers and the nonlinear properties of graphene. Self-induced phase-coherence between naturally incoherent random modes and phase-locked random modes are achieved using lithographically patterning a multilayer graphene film or coupling a saturable absorber graphene reflector. This milestone in the physics of disordered systems paves the way for miniaturized, electrically pumped mode-locked light sources for various applications.
Article
Chemistry, Multidisciplinary
Leonardo Viti, Elisa Riccardi, Harvey E. Beere, David A. Ritchie, Miriam S. Vitiello
Summary: The on-chip integration of two-dimensional nanomaterials with terahertz quantum cascade lasers has led to wide spectral tuning, nonlinear high-harmonic generation, and pulse generation. In this study, a large area multilayer graphene (MLG) was transferred to a THz QCL to monitor its local lattice temperature during operation. The MLG's temperature dependence of electrical resistance was used to measure the local heating of the QCL chip. The results were validated through photoluminescence experiments. This integrated system provides a fast temperature sensor for THz QCLs and enables full electrical and thermal control on laser operation.
Letter
Chemistry, Multidisciplinary
Daisy Q. Wang, Zeb Krix, Oleg P. Sushkov, Ian Farrer, David A. . Ritchie, Alexander R. . Hamilton, Oleh Klochan
Summary: By imposing an external periodic electrostatic potential, the electronic properties of the confined electrons in a quantum well can be different from those in the host semiconductor. In this study, we fabricated and investigated a tunable triangular artificial lattice on a GaAs/AlGaAs heterostructure, where the band structure and Fermi surface can be transformed by altering a gate bias. Magnetotransport measurements revealed multiple quantum oscillations and commensurability oscillations due to electron scattering from the artificial lattice. Increasing the modulation strength revealed new commensurability oscillations caused by electron scattering from the artificial Fermi surface and triangular lattice. These results demonstrate the ability to form artificial two-dimensional crystals with designer electronic properties using low disorder gate-tunable lateral superlattices.
Article
Nanoscience & Nanotechnology
J. D. Fletcher, W. Park, S. Ryu, P. See, J. P. Griffiths, G. A. C. Jones, I. Farrer, D. A. Ritchie, H. -s. Sim, M. Kataoka
Summary: Coulomb forces between high-energy electrons in unscreened regime are detected and analysed using a mesoscopic electron collider. The ability to control Coulomb interactions on picosecond time scales is crucial for quantum logic devices with flying electrons. Despite previous findings, our study reveals Coulomb-dominated collisions of high-energy single electrons in counter-propagating ballistic edge states, indicating new ways to utilize Coulomb interactions for high-speed sensing or gate operations on flying electron qubits.
NATURE NANOTECHNOLOGY
(2023)
Article
Engineering, Electrical & Electronic
C. P. Dobney, A. Nasir, P. See, C. J. B. Ford, J. P. Griffiths, C. Chen, D. A. Ritchie, M. Kataoka
Summary: We have fabricated a device with two lateral p-n junctions on an n-type GaAs/Al0.33Ga0.67As heterostructure. The n-type material was converted to p-type by removing dopants and applying a voltage to a gate in this region. Controlled electroluminescence from both p-n junctions was demonstrated by varying the applied bias voltages. The emitted spectrum peak width was approximately 8 units.
SEMICONDUCTOR SCIENCE AND TECHNOLOGY
(2023)
Article
Physics, Applied
L. Liu, Y. Gul, S. N. Holmes, C. Chen, I. Farrer, D. A. Ritchie, M. Pepper
Summary: In this study, we systematically investigate a structure found in In0.75Ga0.25As heterostructures, and observe its stability and anisotropy in high magnetic fields. This research is important for understanding low-dimensional electronic systems with strong spin-orbit coupling.
APPLIED PHYSICS LETTERS
(2023)
Article
Nanoscience & Nanotechnology
Abdullah M. Zaman, Yuezhen Lu, Nikita W. Almond, Oliver J. Burton, Jack Alexander-Webber, Stephan Hofmann, Thomas Mitchell, Jonathan D. P. Griffiths, Harvey E. Beere, David A. Ritchie, Riccardo Degl'Innocenti
Summary: The study investigates the polarization modulation performance of an integrated metamaterial/graphene device in the THz band. By modifying the graphene's Fermi level, the device's optical response can be modified, enabling active tuning of ellipticity and continuous modification of optical activity. Active circular dichroism and optical activity can be independently exploited by carefully selecting the transmitted frequency and relative angle between the incoming linear polarization and the device's symmetry axis. This all-electronically tuneable versatile polarization device has potential applications in polarization spectroscopy, imaging, and THz wireless generation.
FRONTIERS IN NANOTECHNOLOGY
(2023)
Article
Materials Science, Multidisciplinary
P. M. T. Vianez, Y. Jin, W. K. Tan, Q. Liu, J. P. Griffiths, I. Farrer, D. A. Ritchie, O. Tsyplyatyev, C. J. B. Ford
Summary: Determining the bare electron mass (m0) in crystals is challenging due to many-body effects. By using a one-dimensional geometry, the interaction effects can be separated from m0, and the measured value is (0.0525 +/- 0.0015)me in GaAs. The value of m0 remains constant with varying density, and it is approximately 22% lighter than observed in higher-dimensional GaAs structures, consistent with the quasiparticle picture of a Fermi liquid.
Article
Materials Science, Multidisciplinary
M. J. Rendell, S. D. Liles, A. Srinivasan, O. Klochan, I. Farrer, D. A. Ritchie, A. R. Hamilton
Summary: In two-dimensional systems with a spin-orbit interaction, magnetic focusing is utilized to separate particles with different spins spatially. We conducted measurements on hole magnetic focusing under two different magnitudes of the Rashba spin-orbit interaction. We discovered that the attenuation of a focusing peak, conventionally linked to a change in spin polarization, is actually caused by a change in the scattering of a spin state in hole systems with a k3 spin-orbit interaction. Additionally, we found that the change in scattering length determined through magnetic focusing is consistent with the results obtained from Shubnikov-de Haas oscillations measurements.
Article
Materials Science, Multidisciplinary
S. A. Mikhailov, W. Michailow, H. E. Beere, D. A. Ritchie
Summary: A new photoelectric phenomenon, the in-plane photoelectric (IPPE) effect, has been discovered at terahertz (THz) frequencies in a GaAs/AlxGa1-xAs heterostructure with a two-dimensional (2D) electron gas. It is observed at normal incidence of radiation and can be electrically tunable by gate voltages. The IPPE effect has potential applications in efficient THz radiation detection.
Article
Materials Science, Multidisciplinary
J. Y. Kim, M. Samiepour, E. Jackson, J. Ryu, D. Iizasa, T. Saito, M. Kohda, J. Nitta, H. E. Beere, D. A. Ritchie, A. Hirohata
Summary: In this work, the fabrication of a Fe/n-GaAs spin injection device and the experimental setup for optical gating of the nonlocal spin transport signal were demonstrated. The results showed more uniform current distribution at the Fe/n-GaAs injector interface at bias voltages higher than the Schottky barrier height. Successful spin injection into n-GaAs was confirmed through three- and four-terminal Hanle measurements, with strong interfacial spin dephasing at high magnetic fields. Using a time-resolved pump-probe Kerr rotation setup, a modulation of the nonlocal signal (0.4 +/- 0.3)% depending on the light helicity was observed in Fe/n-GaAs lateral spin injection devices at 30 K.
