Article
Materials Science, Multidisciplinary
Tomas Lothman, Christopher Triola, Jorge Cayao, Annica M. Black-Schaffer
Summary: The EPOCH method is an efficient computational method for calculating time-dependent equilibrium Green's functions in large inhomogeneous systems. It generalizes from quantum chemistry methods and incorporates Fermi-Dirac statistics, with computational cost scaling linearly with system degrees of freedom.
Article
Chemistry, Physical
Nils Wittemeier, Matthieu J. Verstraete, Pablo Ordejon, Zeila Zanolli
Summary: Interference effects in finite sections of one-dimensional moire crystals were investigated using a Landauer-Buttiker formalism within the tight-binding approximation. The study explains interlayer transport in double-wall carbon nanotubes and proposes a predictive model. Results show visible wave function interference at the mesoscale, which can be exploited for designing quantum electronic devices.
Article
Chemistry, Multidisciplinary
Aleksander Bach Lorentzen, Mehdi Bouatou, Cyril Chacon, Yannick J. Dappe, Jerome Lagoute, Mads Brandbyge
Summary: Recent studies have shown the spatial control of nitrogen dopant concentration in graphene using a molecular mask. This technique enables the creation of ballistic electron optics-like structures and has implications for current focusing and quantized conductance.
Article
Chemistry, Physical
Pablo Alvarez-Rodriguez, Victor Manuel Garcia-Suarez
Summary: Research investigates the electronic and transport properties of graphene nanogaps modified with different passivating atoms, revealing variations in conductance and current patterns among different elements.
Article
Chemistry, Multidisciplinary
Lijuan Qian, Shiyu Zhou, Kang Wang, Gang Xiao
Summary: The study reveals that in a one-dimensional half-metallic CrO2 nanoscale conductor, the magnetoresistance induced by a single magnetic domain wall is enhanced by 70 fold when the channel width decreases from 200 nm to 30 nm, due to the increased domain wall resistance and additional contribution of ballistic magnetoresistance. The research predicts that a simple CrO2 nanowire impregnated with a constriction at a 150 nm(2) cross-section could achieve a magnetoresistance ratio of 100%, far exceeding that of a conventional ferromagnetic nanowire.
Article
Chemistry, Multidisciplinary
Daniele Barettin, Alexei V. Sakharov, Andrey F. Tsatsulnikov, Andrey E. Nikolaev, Alessandro Pecchia, Matthias Auf Der Maur, Sergey Yu. Karpov, Nikolay Cherkashin
Summary: This article investigates a possible solution for high-efficiency visible light-emitting diodes (LEDs) using InGaN-quantum-dot-based active regions. Numerical simulations are conducted on a single InGaN island with a size of ten nanometers and nonuniform indium content distribution, which is restored from an experimental image. Various two- and three-dimensional models of the quantum dot are derived, and different calculations and predictions are performed. The impact of InGaN composition fluctuations on the ground-state electron and hole wave functions and quantum dot emission spectrum is analyzed in detail. The applicability of various simulation approaches is assessed by comparing the predicted spectrum with the experimental one.
Article
Physics, Fluids & Plasmas
P. S. Muraev, D. N. Maksimov, A. R. Kolovsky
Summary: This study investigates whether strongly interacting bosons can exhibit ballistic transport, and finds a special state in this regard. It also reveals that, unlike noninteracting bosons, the transporting state of strongly interacting bosons is metastable, meaning that the current decays over time.
Article
Engineering, Electrical & Electronic
Deniz Turkay, Konstantin Tsoi, Ergi Donercark, Rasit Turan, Selcuk Yerci
Summary: Research on contact resistivity in multilayer structures for solar cells emphasizes the importance of minimizing resistivity for high device performance. Various spreading resistance models have been demonstrated for accurately calculating resistance measurements, with a new computationally efficient model proposed. Experimental applicability has been shown using test structures with specific material configurations.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Chemistry, Multidisciplinary
Haixia Hu, Xinyu Mu, Bin Li, Ruohua Gui, Rui Shi, Tao Chen, Jianqiang Liu, Jianyu Yuan, Jing Ma, Kun Gao, Xiaotao Hao, Hang Yin
Summary: The limited charge transport properties of block copolymers and double-cable conjugated polymers hinder the overall performance of single-component photovoltaic devices. This study investigates the barrier formed between the donor-acceptor covalent bond that hinders electron transport in single-component photovoltaic devices and clarifies the difference in transport mechanisms between single-component and bulk heterojunction devices. The study also demonstrates the exceptional advantages of block copolymer-based devices in terms of charge transport properties, stability to compositional variations, film uniformity, and device reproducibility, highlighting the enormous commercial viability of large-area single-component organic solar cells (SCOSCs).
Article
Materials Science, Multidisciplinary
Chao Zhang, Nikolay Prokof'ev, Boris Svistunov
Summary: The study shows that PSSH polarons based on different types of displacement-modulated hopping exhibit distinct properties as the coupling strength increases, with one type exhibiting a diverging effective mass at the critical point and decreasing anisotropically with increasing coupling, while the other type keeps the ground-state momentum at zero and the effective mass monotonously increasing with coupling.
Article
Energy & Fuels
L. Galleni, M. Firat, H. Sivaramakrishnan Radhakrishnan, F. Duerinckx, L. Tous, J. Poortmans
Summary: In this study, temperature-dependent contact resistivity measurements were used to assess electron transport mechanisms in poly-Si passivating contacts. The results showed a transition from tunneling to drift-diffusion transport via pinholes in the SiOx layer with increasing annealing temperature. This transition was found to occur for different oxide thicknesses and oxidation methods.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2021)
Article
Materials Science, Multidisciplinary
Nikolay Prokof'ev, Boris Svistunov
Summary: We report a breakthrough development in solving a broad class of polaron problems with highly nonlinear electron-phonon coupling using a Monte Carlo technique in the coordinate representation. This technique simplifies the models with dispersionless phonons and sheds light on the qualitative and quantitative effects of the "standard" linear displacement-modulated hopping model.
Article
Physics, Multidisciplinary
Ermanno Pinotti, Stefano Longhi
Summary: A quantum particle constrained between two high potential barriers can exhibit quasi-bound states. The decay of the wave function in such states can be accelerated by additional lateral barriers, contrary to intuition. This acceleration is due to resonant tunneling effects and results in deviations from exponential decay.
Article
Nanoscience & Nanotechnology
Saikat Das, Satoshi Sugimoto, Varun Kumar Kushwaha, Yusuke Kozuka, Shinya Kasai
Summary: Magnetization switching can be achieved by utilizing spin-orbit torque, which shows potential for developing non-volatile memory technologies. In this study, we observed charge-to-spin current conversion at the interface between ferromagnetic Ni0.8Fe0.2 and ferroelectric Bi2WO6 thin films. The resulting spin-orbit torque consists of damping-like and field-like components, with an estimated efficiency comparable to contemporary spintronic materials. We propose that the Rashba Edelstein effect and the spin-orbit proximity effect contribute to the charge-to-spin current conversion and the giant efficiency, respectively.
Article
Multidisciplinary Sciences
Kyle Sherbert, Anooja Jayaraj, Marco Buongiorno Nardelli
Summary: This research adopts a direct space approach and develops a hybrid first/second-quantized qubit mapping to construct a single Hamiltonian and cost function for solving the electronic band structure. Compared to previous approaches, this method is technically and conceptually simpler, and is expected to inspire new strategies for tackling highly-correlated materials beyond classical computing.
SCIENTIFIC REPORTS
(2022)
Article
Engineering, Electrical & Electronic
Daniel A. Lemus, James Charles, Tillmann Kubis
JOURNAL OF COMPUTATIONAL ELECTRONICS
(2020)
Article
Nanoscience & Nanotechnology
Tanmoy Das, Eunyeong Yang, Jae Eun Seo, Jeong Hyeon Kim, Eunpyo Park, Minkyung Kim, Dongwook Seo, Joon Young Kwak, Jiwon Chang
Summary: This study demonstrates high-performance all-PtSe2 FETs by vertically integrating a metallic thick PtSe2 source/drain onto the semiconducting ultrathin PtSe2 channel, successfully overcoming the metal contact issue in 2D semiconductors. The transferred metallic PtSe2 induces a semiconductor-to-metal phase transition in the underlying semiconducting PtSe2, achieving fully metallized source/drain and semiconducting channel within the same platform. The PtSe2 FETs exhibit excellent gate tunability, superior mobility, and low contact resistance, providing a new device paradigm for 2D nanoelectronics.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Physics, Applied
Kuang-Chung Wang, Daniel Valencia, James Charles, Alex Henning, Megan E. Beck, Vinod K. Sangwan, Lincoln J. Lauhon, Mark C. Hersam, Tillmann Kubis
Summary: Research on van der Waals p-n heterojunctions has revealed anti-ambipolar behavior and gate tunability, with quantum transport modeling the interface physics and achieving qualitative agreement with experiments in terms of anti-ambipolar characteristics and Gaussian function tunability. Carrier recombination was found to determine the overall current density, with two gates controlling recombination by regulating the density of electrons in MoS2 and holes in black phosphorus at the heterojunction area.
APPLIED PHYSICS LETTERS
(2021)
Article
Nanoscience & Nanotechnology
Dongwook Seo, Jae Eun Seo, Tanmoy Das, Joon Young Kwak, Jiwon Chang
Summary: The study explores the construction of in-plane lateral heterojunction within the same material platform by inducing band offsets in energy bands at the interface. Specifically, the pentagonal palladium diselenide (PdSe2) enables various combinations of different band gaps, facilitating the realization of a gate-controlled rectifier diode. The demonstration of reversible rectifying direction and modulation of current direction through heterojunction barrier height adjustment shows potential for tunable logic gates.
ADVANCED ELECTRONIC MATERIALS
(2021)
Article
Nanoscience & Nanotechnology
Jae Eun Seo, Tanmoy Das, Eunpyo Park, Dongwook Seo, Joon Young Kwak, Jiwon Chang
Summary: Two-dimensional materials are considered key materials for future logic devices due to their excellent electrostatic integrity, but carrier polarity control in 2D material field-effect transistors remains a challenging issue. The carrier polarity in PdSe2 FETs can be modulated simply by changing the metal contact, allowing for the realization of complementary logic functions in PdSe2-based CMOS circuits. Ultimately, this study suggests the potential for PdSe2-based CMOS logic circuits with different metal contacts for n- and p-MOSFETs.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Chemistry, Multidisciplinary
Viet Anh Cao, Minje Kim, Weiguang Hu, Sol Lee, Sukhyeong Youn, Jiwon Chang, Hyo Sik Chang, Junghyo Nah
Summary: This study reports the formation of SnS2/SnS heterostructure thin film using ALD to enhance the output performance of a PENG. The heterostructure significantly increased the piezoelectric response, resulting in improved output voltage and current density. Thickness-controllable large-area uniform thin-film deposition via ALD ensures reproducible output performance and adjustability of output density depending on applications.
Article
Engineering, Electrical & Electronic
Chin-Yi Chen, Hsin-Ying Tseng, Hesameddin Ilatikhameneh, Tarek A. Ameen, Gerhard Klimeck, Mark J. Rodwell, Michael Povolotskyi
Summary: The design of THJ-TFETs addresses the low ON-current challenge of TFETs, but faces limitations due to fabrication challenges with respect to device dimensions and material interfaces. The performance of the original THJ-TFET design is improved by engineering the doping profile to boost resonant tunneling efficiency, resulting in better SS and ON-current. Quantum transport simulations are employed to optimize THJ-TFET design in this study, considering the complexity of devices with multiple quantum wells and material interfaces in the tunneling junction.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Engineering, Electrical & Electronic
Eunyeong Yang, Kyung Rok Kim, Jiwon Chang
Summary: This study presents a theoretical analysis of the performance of FTJ based on CIPS, with quantum transport simulation showing that CIPS-based FTJ can achieve higher TER compared to HfZrO2-based FTJ due to a lower tunneling potential barrier and larger tunneling effective mass.
IEEE ELECTRON DEVICE LETTERS
(2021)
Article
Physics, Applied
Prasad Sarangapani, James Charles, Tillmann Kubis
Summary: In this study, the band tails of various TMD monolayer and multilayer systems on different dielectric substrates are predicted using density-functional theory. It is found that the band tails critically depend on the layer thickness, temperature, doping concentration, and chosen dielectric substrate.
PHYSICAL REVIEW APPLIED
(2022)
Article
Multidisciplinary Sciences
Aujin Hwang, Minseong Park, Youngseo Park, Yeongseok Shim, Sukhyeong Youn, Chan-Ho Lee, Han Beom Jeong, Hu Young Jeong, Jiwon Chang, Kyusang Lee, Geonwook Yoo, Junseok Heo
Summary: Multispectral photodetectors are emerging devices capable of detecting photons in multiple wavelength ranges such as visible (VIS) and near infrared (NIR). These detectors provide additional information beyond human vision, including thermal image and night vision, and are hindered by structural complexity. The proposed Ge/MoS2 van der Waals heterojunction photodetector simplifies operation and reduces peripheral circuitry, offering potential integration of VIS/NIR vision for various applications.
Article
Nanoscience & Nanotechnology
Jae Eun Seo, Eunpyo Park, Tanmoy Das, Joon Young Kwak, Jiwon Chang
Summary: In this study, PdSe2 n- and p-Metal-Oxide Semiconductor Field-Effect Transistors (MOSFETs) were realized without doping processes using the same conventional metal contact. By utilizing the thickness-dependent phase transition in PdSe2, n-type and p-type behaviors were achieved with thin semiconducting PdSe2 channels and either conventional metal or thick semimetallic PdSe2 source/drains. Furthermore, the study successfully demonstrated a complementary metal-oxide semiconductor (CMOS) inverter with interconnecting PdSe2 n- and p-MOSFETs.
ADVANCED ELECTRONIC MATERIALS
(2022)
Article
Nanoscience & Nanotechnology
Sukhyeong Youn, Jiwon Chang
Summary: In this theoretical study, the electronic properties of the metal/Bi2O2Se interface were investigated using density functional theory calculation. The impact of Cr, Pd, Pt, Au, and Bi on monolayer, bilayer, and trilayer Bi2O2Se was explored, along with the consideration of naturally created Se vacancies on the Bi2O2Se surface. It was found that the Bi2O2Se layer is fully metallized in the metal/monolayer Bi2O2Se structure, while the Bi2O2Se layers remain semiconducting in the metal/bilayer and trilayer Bi2O2Se structures, except for the layer adjacent to the metal. Regardless of whether the Se vacancies are filled with metal or not, the semiconducting layers in bilayer and trilayer Bi2O2Se form Ohmic contact with Bi. Filling the Se vacancies with heavier metals than Se increases the interface distance between the metal and Bi2O2Se, resulting in a weak Fermi level pinning effect.
ADVANCED ELECTRONIC MATERIALS
(2023)
Article
Nanoscience & Nanotechnology
Tanmoy Das, Sukhyeong Youn, Jae Eun Seo, Eunyeong Yang, Jiwon Chang
Summary: Achieving effective polarity control of n- and p-type transistors is critical for integrating 2D materials into CMOS logic circuits. By utilizing an aluminum oxide passivation layer, a complete carrier polarity conversion from p- to n-type was achieved, resulting in precisely tuned n-type behavior.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Materials Science, Multidisciplinary
James Charles, Sabre Kais, Tillmann Kubis
ACS MATERIALS LETTERS
(2020)
