Article
Chemistry, Analytical
Hanlin Wu, Fanqi Meng, Xueqin Gong, Wei Tao, Liupeng Zhao, Tianshuang Wang, Fangmeng Liu, Xu Yan, Peng Sun, Geyu Lu
Summary: In this study, the in-situ derived ABO3-based heterostructures were proposed as promising sensitive materials to overcome the intrinsic inferior properties of ABO3 perovskites in chemiresistive sensing. The designed mesoporous p-p heterostructures composites of La2O3/LaFeO3 exhibited high sensitivity, fast response and recovery speed, outstanding selectivity, and low detection limit for gas sensing applications.
SENSORS AND ACTUATORS B-CHEMICAL
(2023)
Article
Multidisciplinary Sciences
Jianwen Song, Xiaoying Kang, Lu Wang, Dan Ding, Deling Kong, Wen Li, Ji Qi
Summary: Researchers have developed a polymer nanoplatform for thrombus imaging and treatment in the near-infrared-II region, offering a versatile approach for the diagnosis and treatment of life-threatening diseases caused by thrombotic disorders.
NATURE COMMUNICATIONS
(2023)
Review
Engineering, Environmental
Abdussamad Mukhtar Mohammed, Safia Syazana Mohtar, Farhana Aziz, Shakhawan Ahmad Mhamad, Madzlan Aziz
Summary: Cuprous oxide is a semiconductor with characteristics of abundance, low toxicity, and easy synthesis, but faces challenges in photocorrosion, stability, and charge carrier recombination. Incorporating other materials to form composite photocatalytic materials is a viable strategy to enhance its performance.
JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING
(2021)
Article
Materials Science, Multidisciplinary
Puteri Haslinda Megat Abdul Hedei, Zainuriah Hassan, Hock Jin Quah
Summary: The study systematically investigated the effects of post-deposition annealing at different temperatures on polycrystalline gallium oxide films, showing improvements in structural, morphological, optical, and electrical characteristics as temperature increased up to a certain point. However, excessive annealing temperature resulted in detrimental effects such as interfacial layer formation due to excessive oxygen anion diffusion and sudden contraction of indirect band gap, suggesting that 1000 degrees C was not a suitable annealing temperature for Ga2O3 films. An optimized annealing temperature of 800 degrees C demonstrated the best leakage current density characteristic due to improved crystallinity and the smallest FWHM.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2022)
Article
Physics, Applied
S. L. Benz, M. Becker, A. Polity, S. Chatterjee, P. J. Klar
Summary: The combination of copper oxides with gallium sesquioxide is considered an excellent heterojunction system for overcoming challenges in solar cell applications. Among the studied heterostructures, the Cu2O/α-Ga2O3 heterostructure appears to offer the most favorable band alignment for photovoltaic applications within the experimental margin of error.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Physics, Multidisciplinary
Yanqiu Sun, Yuan Liu, Siyuan Hong, Zheng Chen, Meng Zhang, Yanwu Xie
Summary: Recent research discovered a critical thickness of around 3 nm for LaAlO3 film on the LaAlO3/KTaO3 (111) interface, beyond which the interface behaves as insulating rather than conducting (or superconducting). In situ transport measurements during growth also revealed that this critical thickness can be suppressed by avoiding exposure to oxygen. These findings suggest that the origin of the electron gas at the interface is dominated by electron transfer from oxygen vacancies in the LaAlO3 film to the KTaO3 substrate.
PHYSICAL REVIEW LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Sven Esser, Jiongyao Wu, Sebastian Esser, Robert Gruhl, Anton Jesche, Vladimir Roddatis, Vasily Moshnyaga, Rossitza Pentcheva, Philipp Gegenwart
Summary: Synthesis and investigation of artificial multilayers of SrRuO3 with SrIrO3 revealed electronic reconstruction, ferromagnetic interlayer coupling, and a negative Berry-curvature contribution to the anomalous Hall effect. The magnetic easy direction rotates with increasing fields, resulting in strong anisotropy of magnetoresistance.
Article
Optics
Hao Chen, Sam Teale, Bin Chen, Yi Hou, Luke Grater, Tong Zhu, Koen Bertens, So Min Park, Harindi R. Atapattu, Yajun Gao, Mingyang Wei, Andrew K. Johnston, Qilin Zhou, Kaimin Xu, Danni Yu, Congcong Han, Teng Cui, Eui Hyuk Jung, Chun Zhou, Wenjia Zhou, Andrew H. Proppe, Sjoerd Hoogland, Frederic Laquai, Tobin Filleter, Kenneth R. Graham, Zhijun Ning, Edward H. Sargent
Summary: The energy landscape of reduced-dimensional perovskites (RDPs) can be tailored by adjusting their layer width. In this study, a method to increase the layer width of RDPs in 2D/3D heterostructures is reported to address electron blocking at the interface. This method allows for the development of efficient inverted perovskite solar cells with high stability.
Article
Chemistry, Multidisciplinary
Congcong Xing, Yu Zhang, Yongpeng Liu, Xiang Wang, Junshan Li, Paulina R. Martinez-Alanis, Maria Chiara Spadaro, Pablo Guardia, Jordi Arbiol, Jordi Llorca, Andreu Cabot
Summary: The photodehydrogenation of ethanol using Cu2O-TiO2 type-II heterojunctions shows high selectivity for acetaldehyde and significantly increased hydrogen evolution rates compared to bare TiO2. Combining energy sources in thermo-photocatalytic reactors proves to be an efficient strategy for solar energy conversion.
Article
Nanoscience & Nanotechnology
Fabian Schoeppach, Daniel Splith, Holger von Wenckstern, Marius Grundmann
Summary: In this study, metal-semiconductor field-effect transistor (MESFET) devices based on pulsed laser deposition (PLD) grown In2O3 thin films are reported. These devices exhibit on-off ratios exceeding 6 orders of magnitude and low sub-threshold swing values close to the thermodynamic limit. Oxygen plasma treatment and compensation doping with Mg are used to suppress the accumulation of electrons at the surface of In2O3, which is a major obstacle for its use as an active material in electronic devices.
ADVANCED ELECTRONIC MATERIALS
(2023)
Article
Chemistry, Physical
Gayatree Barik, Sourav Pal
Summary: In this study, the possibility of using 2D lateral heterostructures as battery electrodes was examined. The results showed that these structures have enhanced electrical conductivity, fast diffusion, and good stability, making them potential candidates for LIBs/SIBs applications.
APPLIED SURFACE SCIENCE
(2022)
Article
Chemistry, Analytical
Anna Paleczek, Bartlomiej Szafraniak, Lukasz Fusnik, Andrzej Brudnik, Dominik Grochala, Stanislawa Kluska, Maria Jurzecka-Szymacha, Erwin Maciak, Piotr Kaluzynski, Artur Rydosz
Summary: Controlling environmental pollution is a pressing issue worldwide, and developing high-performance gas sensors is crucial for pollution control. Through research on the heterostructures of CuO/SnOx and SnOx/CuO, selective detection of NO2 has been achieved.
Article
Chemistry, Multidisciplinary
Xiaotao Xu, Xi He, Anthony T. Bollinger, Xiaoyan Shi, Ivan Bozovic
Summary: A new family of metastable materials, La2-xSrxZnO4 (LSZO), was synthesized by atomic-layer-by-layer molecular beam epitaxy (ALL-MBE), which can form epitaxial materials with a high-temperature superconductor (HTS) compound, La2-xSrxCuO4 (LSCO). By growing La2ZnO4 (LZO) at very low temperatures to form the insulating layer, the superconducting properties of the LSCO electrodes in LSCO/LZO/LSCO trilayers remain undiminished, opening prospects for producing high-quality HTS tunnel junctions.
Article
Multidisciplinary Sciences
Taewon Min, Wooseon Choi, Jinsol Seo, Gyeongtak Han, Kyung Song, Sangwoo Ryu, Hyungwoo Lee, Jungwoo Lee, Kitae Eom, Chang-Beom Eom, Hu Young Jeong, Young-Min Kim, Jaekwang Lee, Sang Ho Oh
Summary: Polarity discontinuity in LaAlO3/SrTiO3 (LAO/STO) heterostructures induces the formation of two-dimensional electron gas (2DEG) and structural distortions involving antiferrodistortive (AFD) rotation and ferroelectric (FE) distortion. AFD and FE modes are cooperatively coupled below the critical thickness in LAO/STO (111) heterostructures, disappearing simultaneously above the critical thickness with the formation of 2DEG. Oxygen vacancy (VO) formation at the LAO (111) surface acts as the source of 2DEG, with the evolution of AFD rotation and FE distortion strongly correlated with VO distribution. This study demonstrates the emergence of AFD and FE modes in oxide heterostructures as a result of the interplay between misfit strain and polar field, with their coupling being tunable by changing the interface orientation.
Article
Chemistry, Physical
Shiming Yan, Zengjie Li, Dunhui Wang, Wenbo Mi
Summary: The study shows that the magnetic moments of Ru atoms in SrRuO3/BiFeO3 heterostructures can change from positive to negative with variations in electric field strength, leading to a large magnetoelectric coupling strength. Additionally, the heterostructures exhibit perpendicular magnetic anisotropy which significantly varies with different stacking patterns and electric field strengths.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Physics, Applied
Sijun Luo, Lukas Trefflich, Susanne Selle, Ron Hildebrandt, Evgeny Krueger, Stefan Lange, Jingjing Yu, Chris Sturm, Michael Lorenz, Holger Von Wenckstern, Christian Hagendorf, Thomas Hoeche, Marius Grundmann
Summary: This paper reports the heteroepitaxial growth of (00.1)-oriented Zn2GeO4 thin films on c-plane sapphire substrates using pulsed laser deposition. The thin films exhibit [11.0] Zn2GeO4// [11.0] Al2O3 and [1(1) over bar.0] Zn2GeO4//[1(1) over bar.0] Al2O3 in-plane orientation relationships. The measured properties include a rocking curve full width at half maximum of 0.35 degrees, a direct bandgap of 4.9 +/- 0.1 eV, and a defect-related photoluminescence emission centered at 2.62 eV with a FWHM of 0.55 eV. This study enhances our understanding of the physical properties and potential device application of Zn2GeO4 thin films.
APPLIED PHYSICS LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Tillmann Stralka, Michael Bar, Fabian Schoeppach, Susanne Selle, Chang Yang, Holger von Wenckstern, Marius Grundmann
Summary: Current probe atomic force microscopy (cp-AFM) measurements reveal the influence of the textured nature of sputtered gamma-CuI (111) thin films on charge carrier transport. The conductive behaviors of grains and grain boundaries (GBs) are differentiated and correlated, showing a clear difference between them. The time-dependent surface changes, possibly caused by atmospheric oxygen, result in the vanishing of charge carrier transport over time.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2023)
Article
Materials Science, Multidisciplinary
Sofie Vogt, Clemens Petersen, Max Kneiss, Daniel Splith, Thorsten Schultz, Holger von Wenckstern, Norbert Koch, Marius Grundmann
Summary: This study presents the structural and electrical properties of undoped and doped alpha-Ga2O3 thin films grown on m-plane sapphire. An undoped alpha-Ga2O3 buffer layer was introduced to improve crystal quality and stabilize the alpha-phase at lower substrate temperatures. Donor doping with tin and germanium achieved high electron mobilities. Suitable annealing temperature for ohmic Ti/Al/Au layer stacks was identified, while high annealing temperatures deteriorated the electrical properties of the thin films, indicating the need for low temperature contacting procedures for alpha-Ga2O3-based devices.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2023)
Article
Physics, Condensed Matter
Evgeny Krueger, Volker Gottschalch, Gabriele Benndorf, Ron Hildebrandt, Ana Lucia Pereira, Michael S. Bar, Steffen Blaurock, Stefan Merker, Chris Sturm, Marius Grundmann, Harald Krautscheid
Summary: This study presents the epitaxial growth of AgxCu1-xI alloy layers and isolated small crystals on Al2O3 (0001) using the close distance sublimation (CDS) technique. Single-phase gamma-AgxCu1-xI thin films are obtained up to an Ag content of approximately 0.5, with the beta-phase also observed at higher Ag contents. The epitaxial relationships between the deposited AgxCu1-xI layers and the Al2O3 substrate, as well as the structure type, are discussed for different alloy compositions. Additionally, a method for depositing polycrystalline single-phase gamma-AgxCu1-xI thin films for Ag contents up to approximately 0.7 is presented based on the solid-state reaction of AgI layers on Al2O3 (0001) substrate with CuI. Furthermore, it is shown that the near-band-edge emission at 2 K is dominated by excitonic recombination, and the spectral position of the emission profile can be tuned by the alloy composition.
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS
(2023)
Article
Nanoscience & Nanotechnology
Jon Borgersen, Robert Karsthof, Vegard Ronning, Lasse Vines, Holger von Wenckstern, Marius Grundmann, Andrej Yu Kuznetsov, Klaus Magnus Johansen
Summary: Significant resistivity variations have been observed in oxides subjected to low ion doses, which cannot be explained by bulk defects. A comparative study of In2O3-based oxides revealed correlations between resistivity evolution, low ion doses, and UV illumination. The resistivity drops were attributed to oxygen desorption facilitated by irradiation/illumination, as confirmed by post-irradiation exposure to oxygen atmosphere.
Review
Materials Science, Coatings & Films
Laurenz Thyen, Daniel Splith, Max Kneiss, Marius Grundmann, Holger von Wenckstern
Summary: We introduce a new technique, MARS-PLD, for area-selective physical vapor deposition. By using a movable mask, we can selectively mask any desired area on a substrate to create multinary material composition gradients. We demonstrated the capabilities of this method by fabricating material gradients in (Mg,Zn)O thin films and on predefined two-dimensional patterns.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2023)
Article
Nanoscience & Nanotechnology
Evgeny Krueger, Michael Seifert, Volker Gottschalch, Harald Krautscheid, Claudia S. Schnohr, Silvana Botti, Marius Grundmann, Chris Sturm
Summary: We studied the excitonic transition energy E-0 and spin-orbit split-off energy Delta(0) of gamma-AgxCu1-xI alloy thin films using reflectivity measurements at temperatures between 20 K and 290 K. The observed bowing behavior of the E-0 transition as a function of alloy composition is explained based on first-principles band structure calculations. The spin-orbit coupling increases with increasing Ag-content, and the temperature-dependent bandgap shift decreases with increasing Ag-content.
Article
Physics, Applied
Andreas Mueller, Sebastian Henn, Evgeny Krueger, Steffen Blaurock, Harald Krautscheid, Marius Grundmann, Chris Sturm
Summary: We report on the photoluminescence emission in copper iodide bulk single crystals induced by two- and three-photon absorption around 1.525eV. The non-linear optical processes were investigated through density-dependent, steady-state, and time-resolved photoluminescence spectroscopy. We observed that the photoluminescence intensity showed an almost parabolic behavior with the excitation power when the excitation energy corresponded to half of the bandgap energy. We also found a cubic contribution that increased with decreasing excitation energy. The ratio between the two- and three-photon absorption cross sections was determined to be approximately 10(-28) cm(2)s.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Condensed Matter
Marius Grundmann
Summary: This study revisits the problem of potential, electrical field, and charge density in a space charge region. Using the Boltzmann approximation, an analytical asymptotic solution is obtained. The exact solution can be found by numerically integrating an analytical function. A comparison is made with the popular abrupt (or depletion) approximation, and an analytical approximation is provided. The analytical approximation for potential, electrical field, and charge density in a space charge (depletion) region shows good agreement with the (numerically) exact solution.
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS
(2023)
Article
Instruments & Instrumentation
Michael Lorenz, Holger Hochmuth, Holger von Wenckstern, Marius Grundmann
Summary: Pulsed laser deposition (PLD) is a highly flexible physical growth technique for thin films of functional materials. This article describes a relatively simple and reliable concept of PLD hardware that enables deposition on large areas (up to 4 inches in diameter) and tailored lateral and vertical composition spreads without the need for time-consuming hardware changes. Different PLD approaches have been implemented in various chambers by using specific and correlated computer-controlled movements of the target, substrate, and masks, along with an appropriate target phase composition.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2023)
Article
Nanoscience & Nanotechnology
Fabian Schoeppach, Daniel Splith, Holger von Wenckstern, Marius Grundmann
Summary: In this study, metal-semiconductor field-effect transistor (MESFET) devices based on pulsed laser deposition (PLD) grown In2O3 thin films are reported. These devices exhibit on-off ratios exceeding 6 orders of magnitude and low sub-threshold swing values close to the thermodynamic limit. Oxygen plasma treatment and compensation doping with Mg are used to suppress the accumulation of electrons at the surface of In2O3, which is a major obstacle for its use as an active material in electronic devices.
ADVANCED ELECTRONIC MATERIALS
(2023)