Article
Materials Science, Multidisciplinary
Qinxuan Li, Caihong Jia, Yong Ren, Ying Zhang, Weifeng Zhang
Summary: The negative differential resistance (NDR) in ZnO/Nb:SrTiO3 heterojunctions is strongly dependent on negative pulse amplitude/width and compliance current. The NDR intensity and location exhibit the same trend when varying the negative pulse amplitude, width, and compliance current, which can be understood from the variance of concentration of ionized oxygen vacancies and the depletion layer width. This will promote the application of NDR devices.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2021)
Article
Engineering, Electrical & Electronic
Qinxuan Li, Caihong Jia, Ying Zhang, Weifeng Zhang
Summary: The study revealed that NDR characteristics in BaTiO3/Nb:SrTiO3 heterojunctions are influenced by positive and negative pulse amplitudes and widths, but not by ferroelectric polarization. Increase in pulse amplitude and width enhances NDR while reducing the low resistance state and keeping the high resistance state almost unchanged.
ACS APPLIED ELECTRONIC MATERIALS
(2021)
Article
Nanoscience & Nanotechnology
Alexander D. Pogrebnjak, Richard F. Webster, Richard D. Tilley, Vladimir V. Buranich, Volodymyr I. Ivashchenko, Yoshihiko Takeda, Keiji Oyoshi, Rimma Sakenova, Katarzyna Piotrowska, Pawel Zukowski, Piotr Konarski, Anatoliy Kupchishin, Piotr Budzynski
Summary: The study investigated the effects of Si-ion implantation on CrN/ZrN multi nanolayers, revealing moderate radiation-tolerance and changes in composition homogeneity and structure crystallinity within the ion range. The asymmetric distribution of Si negative ions and the formation of Si-rich interfaces were attributed to the strong Si-Cr bindings and differences in displacement energies of ZrN and CrN. Wear resistance and friction coefficient enhancement were observed in the nanoscale coating due to the presence of amorphous Si particles from the interfacial areas.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Nanoscience & Nanotechnology
Jose J. Perez-Grau, Patricio Ramirez, Vladimir Garcia-Morales, Javier Cervera, Saima Nasir, Mubarak Ali, Wolfgang Ensinger, Salvador Mafe
Summary: This study experimentally and theoretically describes the fluoride-induced negative differential resistance (NDR) phenomena observed in conical nanopores operating in aqueous electrolyte solutions. Different parameters were found to affect the NDR effect, leading to the proposal of a two-region conductance model.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Engineering, Electrical & Electronic
Parnia Bastani, Seyed Majid Mohseni, Loghman Jamilpanah, Behnam Azizi, Javad Shoa E. Gharehbagh
Summary: This study investigates the interface effects between conductive graphene (Gr) and semiconducting MoSe2 layers, and finds that the Gr/MoSe2 heterostructure exhibits memristance and negative differential resistance (NDR) behavior. The layers are fabricated using chemical vapor deposition, and electronic effects are shown to govern the observed NDR effects.
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
(2022)
Article
Engineering, Electrical & Electronic
Punya Mainali, Phadindra Wagle, Nishan Khatri, Chasen McPherson, Kaan Kalkan, D. N. McIlroy
Summary: The resistive switching phenomenon at a power level of nW has been observed in a porous alpha-Fe2O3 thin film, which is attributed to the trapping and de-trapping of carriers at the space charge region formed by the movement of ions. The film is prepared under specific conditions and exhibits the phenomenon in a humidity-controlled environment.
SENSORS AND ACTUATORS A-PHYSICAL
(2023)
Article
Engineering, Electrical & Electronic
Phuong Y. Le, Amanda Gazzana, Billy J. Murdoch, Dougal G. McCulloch, David R. McKenzie, Hiep N. Tran, Jim G. Partridge
Summary: Hysteresis and NDR were observed in lateral devices featuring planar graphitic electrodes separated by a nitrogen-doped amorphous carbon (a-CNx) layer. The devices were fabricated using energetic physical vapor deposition and electron-beam lithography. The presence of NDR at a well-defined voltage/electric field in devices formed on a-CNx layers deposited with N-2 pressure of 0.10 mTorr indicates field-induced trapping/detrapping at one of the graphite/a-CNx interfaces.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Engineering, Electrical & Electronic
Zuoheng Jiang, Mengyuan Hua, Xinran Huang, Lingling Li, Chengcai Wang, Junting Chen, Kevin J. Chen
Summary: In this article, the impacts of off-state gate bias on the dynamic on-resistance in p-GaN Gate high-electron-mobility transistors are investigated. It is found that more negative off-state gate bias can worsen the degradation of dynamic on-resistance, especially when switching with a high drain bias. The influences of off-state gate bias on switching transients and off-state stress are explored to reveal the underlying mechanisms.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2022)
Article
Physics, Multidisciplinary
Han Ma, Huixin Li, Dan Li, Huiqing Zhang, Yuanyuan Miao, Junfeng Ren, Guichao Hu
Summary: This study theoretically investigates spin-dependent transport in organic-ferromagnetic devices with spin radicals. A spin-resolved negative differential resistance phenomenon and spin-filtering effect are observed. A new mechanism, bias-induced distinct localization of the spin-split flat-band states, is proposed, which is attributed to the weaker hybridization of the flat-band states rather than the pi-conjugated orbitals. The peak-to-valley ratio increases with the interaction strength between the main chain and radicals. This work explores the unique transport property of flat-band states and their potential in designing high-performance organic spintronic devices.
Article
Engineering, Electrical & Electronic
Tianyu Yu, Weifeng Lu, Zhifeng Zhao, Peng Si, Kai Zhang
Summary: This study investigates the negative DIBL and NDR effects in NCFETs with a fully depleted silicon-on-insulator structure, showing that these effects are closely related to the decrease in internal gate voltage. The newly defined parameter R-PE can quantify the DIBL effect and describe the NDR effect. Our findings suggest that DIBL tends to be consistent with the same R-PE, while the DIBL effect decreases and the NDR effect increases with decreasing R-PE.
MICROELECTRONICS JOURNAL
(2021)
Article
Engineering, Electrical & Electronic
Zhijiang Wang, Xiaoxin Xie, Ligong Zhang, Ronggen Cao, Xiaoyan Liu, Sungjae Cho, Fei Liu
Summary: In this study, a new type of cold source diode (CSDs) is proposed and investigated, which can break the limit of the ideality factor in conventional Schottky diodes and achieve steep switching. CSDs use cold metals of monolayer 2H phase MX2 with energy gaps as the injection source, effectively filtering high-energy electrons and suppressing leakage current.
IEEE ELECTRON DEVICE LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Ruiqing Cheng, Lei Yin, Rui Hu, Huijun Liu, Yao Wen, Chuansheng Liu, Jun He
Summary: This study reports the modulation of a unique NDR effect in ambipolar black phosphorus transistors, which exhibit high peak current density and operating temperature. The NDR peak current and voltage can be effectively modulated by the strong coupling between the channel and the gate electrode.
ADVANCED MATERIALS
(2021)
Article
Chemistry, Multidisciplinary
Mehrzad Soleimany, Marin Alexe
Summary: SrTiO3 crystals exhibit unique photoelectric characteristics, including non-linear electron transport and voltage-controlled negative resistance, when excited by light. The negative resistance leads to the instability of the photocurrent and the spontaneous generation of low-frequency Gunn-like oscillations.
Article
Engineering, Electrical & Electronic
Haibing Qiu, Shan Jin, Wenxian Yang, Xue Zhang, Ying Gu, Peng Zhang, Lifeng Bian, Shulong Lu
Summary: This study finds that deep-level defects in epitaxial materials significantly affect the negative differential resistance (NDR) of GaN-based resonant tunneling diodes (RTDs). Through experiments and first-principles calculations, it is confirmed that there are two deep-level defects at the active region tunneling interface. Additionally, threading dislocations are not the main factor causing NDR degradation in the prepared RTDs.
ACS APPLIED ELECTRONIC MATERIALS
(2022)
Article
Physics, Applied
Hajime Okumoto, Tetsuo Tsutsui
Summary: The study demonstrates that self-heating of devices is a source of negative capacitance in organic light-emitting diodes and hole-only devices. The principal mechanism of negative capacitance is the nonlinear coupling of the real and imaginary parts of admittance caused by AC temperature modulation. External heating induced negative capacitance, reflecting the heat transfer characteristics of the devices.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2021)
Article
Multidisciplinary Sciences
Yunfei Gao, Yao Yang, Roberto Schimmenti, Ellen Murray, Hanqing Peng, Yingming Wang, Chuangxin Ge, Wenyong Jiang, Gongwei Wang, Francis J. DiSalvo, David A. Muller, Manos Mavrikakis, Li Xiao, Hector D. Abruna, Lin Zhuang
Summary: This study presents the design of a Ni@CNx electrocatalyst with a carbon shell for enhanced HOR kinetics in alkaline membrane fuel cells. The Ni@CNx anode, when paired with a Co-Mn spinel cathode, achieved a record peak power density of over 200 mW/cm(2). The strategy described in this study marks a milestone in the development of low-cost hydrogen fuel cells and other energy technologies.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Materials Science, Multidisciplinary
Lucille A. Giannuzzi, Michael Colletta, Yue Yu, Lena F. Kourkoutis, Andrew D. Iams, Kyle Beggs, Alain J. Kassab
Summary: This work presents cryo-EXLO technology for pre-treatment of samples for cryo-TEM analysis. The steps and apparatus for cryo-EXLO are described, along with methods to limit ice contamination. The successful application of cryo-EXLO to polymer and plunge-frozen yeast cell specimens demonstrates its potential for beam-sensitive, liquid, or biological materials.
MICROSCOPY AND MICROANALYSIS
(2023)
Article
Materials Science, Coatings & Films
Tobias Schwaigert, Salva Salmani-Rezaie, Matthew R. Barone, Hanjong Paik, Ethan Ray, Michael D. Williams, David A. Muller, Darrell G. Schlom, Kaveh Ahadi
Summary: Strain-engineering is used to tune the instabilities of incipient ferroelectrics. High-quality KTaO3 thin films are grown by molecular-beam epitaxy. Excess potassium and a combination of ozone and oxygen are supplied with the TaO2 (or tantalum) molecular beams to grow the films with atomically abrupt interfaces. Atomic force microscopy reveals atomic steps at the film surface. Reciprocal space mapping demonstrates coherent strain to the substrates when the films are thin enough.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2023)
Article
Chemistry, Physical
Berit H. H. Goodge, Benjamin Geisler, Kyuho Lee, Motoki Osada, Bai Yang Wang, Danfeng Li, Harold Y. Y. Hwang, Rossitza Pentcheva, Lena F. F. Kourkoutis
Summary: Nickel-based superconductors provide an experimental platform for exploring cuprate-like superconductivity. However, superconductivity in nickelates has only been observed in thin films, which raises questions about the polar interface between substrate and film. In this study, the authors investigate the interface between Nd1-xSrxNiO2 and SrTiO3 using advanced characterization techniques and theoretical calculations, revealing the formation of a single intermediate Nd(Ti,Ni)O-3 layer and its role in reducing interface charge density. Understanding the complex interface structure is important for the future synthesis of nickelate films on other substrates and in vertical heterostructures.
Review
Physics, Multidisciplinary
Javier Junquera, Yousra Nahas, Sergei Prokhorenko, Laurent Bellaiche, Jorge iniguez, Darrell G. Schlom, Long-Qing Chen, Sayeef Salahuddin, David A. Muller, Lane W. Martin, R. Ramesh
Summary: The past decade has witnessed significant progress in understanding emergent topological polar textures in oxide nanostructures, including vortices, skyrmions, merons, hopfions, dipolar waves, and labyrinthine domains. The discovery of low-dimensional ferroelectric oxide nanostructures has altered the perceived energy cost associated with the formation of these structures, allowing for manipulation of order parameters. This review provides a historical context, scientific description, and discussion of the potential applications and future challenges in this field.
REVIEWS OF MODERN PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Yao Yang, Yu-Tsun Shao, Jianbo Jin, Julian Feijoo, Inwhan Roh, Sheena Louisia, Sunmoon Yu, Maria V. Fonseca Guzman, Chubai Chen, David A. Muller, Hector D. Abruna, Peidong Yang
Summary: The design and synthesis of nanocatalysts with well-defined sizes, compositions, and structures have greatly enhanced our ability to control catalyst activity and selectivity for energy-related electrochemical reactions. By using operando electrochemical liquid-cell scanning transmission electron microscopy (EC-STEM), the dynamic evolution of Cu nanocatalysts during CO2 electroreduction was observed, providing valuable insights into their active states. With further technical advancements, operando EC-STEM is expected to become a powerful electroanalytical method for studying nanoscale electrocatalysts at solid/liquid interfaces.
ACS SUSTAINABLE CHEMISTRY & ENGINEERING
(2023)
Article
Nanoscience & Nanotechnology
Nathaniel J. Schreiber, Ludi Miao, Berit H. Goodge, Lena F. Kourkoutis, Kyle M. Shen, Darrell G. Schlom
Summary: Molecular-beam epitaxy enables the combination of ultrathin functional materials to create emergent phenomena at the interface. In this study, a model heterostructure with engineered Berry curvature is synthesized to reproduce a hump-like feature, commonly attributed to the presence of skyrmions. However, despite the clear hump, no evidence of skyrmions is found.
Article
Multidisciplinary Sciences
Ethan G. Arnault, Athby H. Al-Tawhid, Salva Salmani-Rezaie, David A. Muller, Divine P. Kumah, Mohammad S. Bahramy, Gleb Finkelstein, Kaveh Ahadi
Summary: A two-dimensional, anisotropic superconductivity was found at the KTaO3(111) interfaces, which violates the Pauli limit and is robust against in-plane magnetic field. The study shows that the Cooper pairs are more resilient when the bias is along [112] and the magnetic field is along [110]. The anisotropic nature of superconductivity is discussed in the context of electronic structure, orbital character, and spin texture at the KTaO3(111) interfaces.
Article
Nanoscience & Nanotechnology
Abigail Freyer, Trevor M. Tumiel, Michelle Smeaton, Benjamin H. Savitzky, Lena F. Kourkoutis, Todd D. Krauss
Summary: Cation exchange is commonly used for doping nanocrystals, but the relationships between the exchange process, the doped products, and the resulting photophysics are not well understood. Single molecule investigations of Ag+ doping on CdSe nanocrystals reveal the presence of multiple species within a single sample, suggesting that the differences in optical properties are due to the contributions of each species. The heterogeneity of the doped samples highlights the challenges in controlling the cation exchange method for producing homogeneous samples.
ACS NANOSCIENCE AU
(2023)
Article
Chemistry, Multidisciplinary
Fengdeng Liu, Prafful Golani, Tristan K. Truttmann, Igor Evangelista, Michelle A. Smeaton, David Bugallo, Jiaxuan Wen, Anusha Kamath Manjeshwar, Steven J. May, Lena F. Kourkoutis, Anderson Janotti, Steven J. Koester, Bharat Jalan
Summary: The alkaline earth stannates, specifically CaSnO3, have been proven to be a promising ultrawide band gap semiconductor with high room-temperature electron mobilities. Previous theoretical studies and doping attempts had labeled CaSnO3 as an undopable material, but using hybrid molecular beam epitaxy, the researchers successfully demonstrated predictable doping of CaSnO3 using lanthanum as an n-type dopant. The resulting films exhibited high electron concentrations and impressive room-temperature mobility, leading to the fabrication of CaSnO3-based field-effect transistors with low off-state leakage and high on-off ratios. This work serves as a starting point for further exploration of CaSnO3's semiconducting properties and potential applications.
Article
Materials Science, Multidisciplinary
Megan E. Holtz, Elliot Padgett, Aaron C. Johnston-Peck, Igor Levin, David A. Muller, Andrew A. Herzing
Summary: Measuring local polar ordering is crucial for understanding ferroelectricity in thin films. The cepstral approach allows us to determine the local polar displacements that drive ferroelectricity from nanobeam electron diffraction patterns. Experimental results demonstrate that this technique achieves a precision of 1.1 pm in mapping polar displacements with nanometer resolution.
MICROSCOPY AND MICROANALYSIS
(2023)
Article
Chemistry, Multidisciplinary
Michelle A. Smeaton, Noah Schnitzer, Hong Zheng, J. F. Mitchell, Lena F. Kourkoutis
Summary: Measurement of picometer-scale atomic displacements by aberration-corrected STEM is crucial in studying crystalline materials, as it can provide insights into ordering mechanisms and local heterogeneities. However, HAADF-STEM imaging, commonly used for such measurements, is considered insensitive to light atoms like oxygen. This study demonstrates that cation sites in distorted perovskites can appear displaced from their true positions due to the effect of light atoms and crystal symmetry, which can be minimized by adjusting sample thickness and beam voltage or by reorienting the crystal.
Article
Nanoscience & Nanotechnology
Zeming Sun, Darrah K. Dare, Zhaslan Baraissov, David A. Muller, Michael O. Thompson, Matthias U. Liepe
Summary: It has been believed that intermetallic Nb3Sn alloys form through Sn diffusion into Nb. However, our findings of significant oxygen content in Nb3Sn led us to investigate alternative formation mechanisms. Through experiments with different oxide interfaces, we have demonstrated a thermodynamic route that challenges the conventional Sn diffusion mechanism and highlights the involvement of a SnOx intermediate phase. This new mechanism provides principles for growth optimization and synthesis of high-quality Nb3Sn superconductors.
Article
Nanoscience & Nanotechnology
L. van Deurzen, J. Singhal, J. Encomendero, N. Pieczulewski, C. S. Chang, Y. Cho, D. A. Muller, H. G. Xing, D. Jena, O. Brandt, J. Laehnemann
Summary: Using low-temperature cathodoluminescence spectroscopy, the properties of N- and Al- polar AlN layers grown on bulk AlN{0001} by molecular beam epitaxy are studied. Both polarities of layers exhibit a suppression of deep-level luminescence compared to the bulk AlN substrate, a total absence of the prevalent donor with an exciton binding energy of 28 meV, and a much increased intensity of the emission from free excitons. The dominant donor in these layers has an associated exciton binding energy of 13 meV. Additionally, the observation of excited exciton states up to the exciton continuum allows for the direct extraction of the Γ(5) free exciton binding energy of 57 meV.
Article
Chemistry, Physical
Ming Zhou, Dasol Yoon, Yao Yang, Lihua Zhang, Can Li, Hongsen Wang, Anju Sharma, Shaojie Jiang, David A. A. Muller, Heictor D. Abruna, Jiye Fang
Summary: We developed a simple method to synthesize uniform-sized (9 nm) CoMn2O4 spinel nano-octahedra with {101} facets. Compared to their spherical counterparts and previously reported spinel electrocatalysts, these nano-octahedra exhibited enhanced electrocatalytic activity for the oxygen reduction reaction (ORR) in alkaline media. They achieved a high mass activity (MA) of 60.0 A/g at 0.85 V, surpassing their spherical counterparts (38.6 A/g). The CoMn2O4 nano-octahedra also showed favorable stability, maintaining an MA of 47.2 A/g after 10,000 durability cycles. This study highlights the promising approach of synthesizing advanced spinel nanooxides with controlled crystal facets for nonprecious metal ORR electrocatalysts, emphasizing the significance of catalyst shape control.
ACS ENERGY LETTERS
(2023)
