Article
Multidisciplinary Sciences
Yu-Wei Liu, Dun-Jie Zhang, Po-Cheng Tsai, Chen-Tu Chiang, Wei-Chen Tu, Shih-Yen Lin
Summary: Thin copper films were deposited on 2D material surfaces through e-beam deposition, exhibiting preferential planar growth on both MoS2 and WSe2 surfaces. The films showed low resistivity values and the ability of WSe2 to prevent diffusion of copper. WSe2 is a promising candidate for replacing liner/barrier stack in interconnects due to its low resistivity, thin body nature, and unique van der Waals epitaxy growth mode.
SCIENTIFIC REPORTS
(2022)
Article
Nanoscience & Nanotechnology
A. Y. Polyakov, V. I. Nikolaev, A. I. Pechnikov, S. I. Stepanov, E. B. Yakimov, M. P. Scheglov, I. V. Shchemerov, A. A. Vasilev, A. A. Kochkova, A. V. Chernykh, A. V. Chikiryaka, S. J. Pearton
Summary: Thick films (23 μm) of kappa-Ga2O3 were successfully grown on GaN/sapphire templates using Halide Vapor Phase Epitaxy (HVPE). The films exhibited good crystalline quality and surface morphology. They possessed specific properties such as a wide absorption band and deep-level traps.
Article
Chemistry, Physical
Tao Zhang, Yifan Li, Yachao Zhang, Qian Feng, Jing Ning, Chunfu Zhang, Jincheng Zhang, Yue Hao
Summary: Beta-Ga2O3 films were grown on epi-GaN/sapphire substrates at different temperatures by low pressure MOCVD. The crystal structure, surface morphology, and element chemical state were influenced by temperature. Higher temperature led to improved crystal quality and surface morphology, as confirmed by XRD, AFM, and SEM analyses.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Chemistry, Analytical
Junjun Wang, Zhanying Zhang, Oliver Rettig
Summary: In this study, intrinsically n-doped a-plane and c-plane GaN thin films were deposited on sapphire substrates using MOVPE. The c-plane GaN sensor exhibited a much higher response to TEA and could detect the vapor down to a lower threshold compared to the a-plane sensor. The better TEA sensing performance of the c-plane sensor was attributed to the lower adsorption energy and higher electron accumulation around O-2 molecules on its surface facet.
SENSORS AND ACTUATORS B-CHEMICAL
(2021)
Article
Nanoscience & Nanotechnology
Mehdi Akbari-Saatlu, Marcin Procek, Claes Mattsson, Goran Thungstrom, Tobias Torndahl, Ben Li, Jiale Su, Wenjuan Xiong, Henry H. Radamson
Summary: Designing heterostructure materials at the nanoscale is a well-known method to enhance gas sensing performance. In this study, ZnO/SnO2 heterostructures were grown on alumina substrates using the ultrasonic spray pyrolysis method. The results showed that the sensitivity of the sensor to H2S gas can be altered by changing the zinc chloride content in the precursor, and the heterostructures with a 5:1 ratio of ZnCl2 to SnCl2·2H(2)O exhibited the highest response. The gas sensing mechanism of the ZnO/SnO2 heterostructures was analyzed and attributed to the formation of the heterostructure between ZnO and SnO2.
ACS APPLIED NANO MATERIALS
(2022)
Article
Materials Science, Ceramics
Kai Chen, Yachao Zhang, Jincheng Zhang, Xing Wang, Yixin Yao, Jinbang Ma, Yue Hao
Summary: By analyzing the growth modes of GaN films on AlN buffer layers with different thicknesses, a new growth model of GaN on AlN buffer was proposed in this study. Under optimal conditions, AlGaN/GaN/AlN heterostructures showed excellent performance.
CERAMICS INTERNATIONAL
(2022)
Article
Materials Science, Multidisciplinary
Sudhanshu Gautam, V Aggarwal, Bheem Singh, Rahul Kumar, J. S. Tawale, B. S. Yadav, R. Ganesan, V. N. Singh, S. P. Singh, M. Senthil Kumar, S. S. Kushvaha
Summary: Thin films of Bi2Se3 were deposited on various substrates using magnetron sputtering. The films were found to have good crystalline quality, pure rhombohedral phase, and truncated hexagonal morphology. The optical bandgap of the films was in the range of 1.40-1.48 eV, and they showed potential for the development of futuristic devices.
JOURNAL OF MATERIALS RESEARCH
(2023)
Article
Materials Science, Multidisciplinary
Jaroslaw Mazuryk, Katarzyna Klepacka, Joanna Piechowska, Jakub Kalecki, Ladislav Derzsi, Piotr Piotrowski, Piotr Paszke, Dorota A. Pawlak, Simone Berneschi, Wlodzimierz Kutner, Piyush Sindhu Sharma
Summary: The present research reports on the in-water, site-specific photodeposition of glyphosate-containing polyacrylamide nanofilms. The successful photodeposition was confirmed through material characterization and analysis. Additionally, the study found that glyphosate had an impact on polymer gelation. These findings are important for the development of glyphosate-based nanomaterials and chemical sensors.
ACS APPLIED POLYMER MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Jerome Medard, Xiaonan Sun, Jean Pinson, Da Li, Claire Mangeney, Jean-Philippe Michel
Summary: This study demonstrates two different molecular organizations obtained from octadecylamine molecules on a highly oriented pyrolytic graphite surface using Langmuir-Blodgett transfer and oxidative electrografting: self-organized physisorbed molecules lying flat on the surface and compact crystalline monolayers of molecules standing upright. The upright molecular organization maintains a hexagonal symmetry with lattice parameters intermediate between Langmuir films and the HOPG surface. These structures may have applications in sensor design, biomedical applications, organic electronics, and energy storage devices.
Article
Chemistry, Physical
Qicheng Hu, Ki-Bong Nam, Jin-Ho Yeo, Mun-Ja Kim, Ji-Beom Yoo
Summary: By fabricating a carbon-supersaturated Ni foil and depositing an additional Ni film on top of it, the uneven morphologies and qualities of multilayer-graphene or nanometer-thick graphite films on Ni grains with different orientations can be improved. Rapid formation of NGF on the Ni film after re-annealing the Ni film/ss-Ni foil system results in enhanced thickness and quality uniformity.
Article
Chemistry, Multidisciplinary
Jiong Wang, Liang Ma, Xiangyi Wang, Xiaohan Wang, Junjie Yao, Qinghua Yi, Rujun Tang, Guifu Zou
Summary: This research introduces a novel atomic chemical-solution strategy to grow sub-nanometric NiO thin films with surface ferromagnetic behaviors. The thin film exhibits the highest reported room-temperature ferromagnetic behavior and can be used as atomic layer magnetic units in future transparent magnetoelectric devices.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Nanoscience & Nanotechnology
Ahmed Chnani, Mario Kurniawan, Andreas Bund, Steffen Strehle
Summary: This study presents a surprisingly simple fabrication method for efficient, stable, and cost-effective nanometer-thick hematite films. These films exhibit superior photo-oxidation stability and high photocurrent density, surpassing any value achieved by hematite and other single-material thin-film photoanodes.
ACS APPLIED NANO MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Lin Zhang, Jiejun Wu, Tong Han, Fang Liu, Mengda Li, Xingyu Zhu, Qiyue Zhao, Tongjun Yu
Summary: This paper investigated the growth of semi-polar GaN thick films on an m-plane sapphire by HVPE, obtaining (11-22) and (10-13) films with mirror surfaces and excellent crystal quality on different GaN templates. The influence of MO-GaN templates on HVPE growth was studied, showing that single-phase growth was predominant on single-phase templates, while mixed-phase templates led to single-phase growth. Calculation of formation energy and migration barrier of semi-polar faces indicated that (11-22)-plane growth was more likely to occur due to lower barriers.
Article
Materials Science, Multidisciplinary
Ze Mei, Shuo Deng, Lijie Li, Xiaoyan Wen, Haifei Lu, Min Li
Summary: In this study, we report the fabrication of continuous Au films with thicknesses of 5.4, 6.6, and 7.5 nm on a Chromium seed layer, and their corresponding dielectric function measurements using ellipsometry and first principles calculation. The results show that the real part of dielectric function of the Au films is mostly negative, indicating their continuity, and the imaginary part decreases with increasing thickness due to reduced surface electron scattering. Both the calculated and measured results exhibit good agreement in a specific wavelength range. Additionally, both parts of the dielectric function decrease as the thickness of the Au film increases, providing valuable insights for designing nano-photoelectronic devices involving sub-10 nm Au films.
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
(2021)
Article
Chemistry, Physical
Milosz Grodzicki, Jakub Sito, Rafal Lewandkow, Piotr Mazur, Antoni Ciszewski
Summary: This report presents the research results on the electronic structure of three interfaces consisting of organic layers of Alq(3), Gaq(3), or Erq(3) deposited on GaN semiconductor. The formation and characterization of the interfaces were performed in situ under ultrahigh vacuum conditions. The band energy diagrams of the substrate and interfaces were constructed using ultraviolet photoelectron spectroscopy (UPS) assisted by X-ray photoelectron spectroscopy (XPS). The study found that the highest occupied molecular orbitals (HOMOs) of Alq(3), Gaq(3), and Erq(3) layers are at 1.2, 1.7, and 2.2 eV, respectively. The Alq(3) layer does not affect the position of the vacuum level of the substrate, unlike the Gaq(3) and Erq(3) layers, which lower it by 0.8 eV and 1.3 eV, respectively. The interface dipoles at the phase boundaries were found to be -0.2, -0.9, and -1.2 eV for Alq(3), Gaq(3), and Erq(3) layers on GaN(0001) surfaces.
Article
Physics, Applied
Wen Hsin Chang, Naoya Okada, Masayo Horikawa, Takahiko Endo, Yasumitsu Miyata, Toshifumi Irisawa
Summary: The study demonstrates that depositing ZrO2 directly on MoS2 through low-temperature ALD can suppress oxidation, reduce damage to the MoS2 channel, lower interfacial traps, and improve device performance of 1L MoS2 nMOSFETs. Low thermal budget post-deposition annealing is effective for achieving a low CET of 2.3 nm, promising for future TMDC top gate devices with high-quality interfaces.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2021)
Article
Engineering, Electrical & Electronic
Noriyuki Uchida, Yuta Nakajima, Leonid Bolotov, Wen-Hsin Chang, Tatsuro Maeda, Yuji Ohishi
Summary: The thermal transport properties of Amorphous Al2O3 films deposited on Ge substrates were studied using the thermo-reflectance method. It was found that the thermal conductivity of the films was significantly lower compared to crystalline Al2O3, and the thermal resistivity of the Al2O3/Ge interface was relatively high. Phonon-based and diffuson theories were used to simulate the thermal transport, with diffuson theory providing a better explanation for the observed low thermal conductivity of ALD-Al2O3.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2021)
Article
Materials Science, Multidisciplinary
Kazuaki Oishi, Hiroyuki Ishii, Wen Hsin Chang, Hiroto Ishii, Akira Endoh, Hiroki Fujishiro, Tatsuro Maeda
Summary: The research found that InGaAs photo field-effect transistors on Si exhibit higher and broader responsivity characteristics compared to InGaAs photodiodes.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2021)
Article
Physics, Applied
Y. H. G. Lin, H. W. Wan, L. B. Young, J. Liu, Y. T. Cheng, K. Y. Lin, Y. J. Hong, C. T. Wu, J. Kwo, M. Hong
Summary: By depositing Y on a pristine p-InAs surface under ultra-high vacuum conditions, the researchers achieved low interfacial trap density, paving the way for effective passivation of p-type InAs and high-performance electronic and optoelectronic InAs devices.
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Applied
Tatsuro Maeda, Kazuaki Oishi, Hiroyuki Ishii, Wen Hsin Chang, Tetsuji Shimizu, Akira Endoh, Hiroki Fujishiro, Takashi Koida
Summary: By utilizing a TCO gate, high optical responsivity and broadband photosensitivity were demonstrated in InGaAs photoFETs, making them a promising architecture for FSI photodetectors integrated with optical communication devices and Si-LSI.
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Applied
Wen Hsin Chang, Hsien-Wen Wan, Yi-Ting Cheng, Yen-Hsun G. Lin, Toshifumi Irisawa, Hiroyuki Ishii, Jueinai Kwo, Minghwei Hong, Tatsuro Maeda
Summary: In this study, Germanium-on-insulator (GeOI) structures with a surface orientation of (111) were successfully fabricated using low thermal budget epitaxial-lift-off (ELO) technology. The material characteristics and transport properties of the Ge(111)OI structure were systematically investigated. The results indicate the potential of low thermal budget ELO technology for integrating Ge channels with different surface orientations.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Physics, Applied
L. B. Young, J. Liu, Y. H. G. Lin, H. W. Wan, L. S. Chiang, J. Kwo, M. Hong
Summary: We have achieved a record low subthreshold slope in InGaAs MOSFETs at 300 K by using in situ deposited Al2O3/Y2O3 as a gate dielectric and a self-aligned inversion-channel gate-first process. The temperature-dependent transfer characteristics showed a linear reduction of subthreshold slope with temperature, reaching a value comparable to state-of-the-art InGaAs FinFET at 77 K.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Nanoscience & Nanotechnology
Mitsuhiro Okada, Naoka Nagamura, Tarojiro Matsumura, Yasunobu Ando, Anh Khoa Augustin Lu, Naoya Okada, Wen-Hsin Chang, Takeshi Nakanishi, Tetsuo Shimizu, Toshitaka Kubo, Toshifumi Irisawa, Takatoshi Yamada
Summary: This study reports the formation of a monolayer p-n junction in MoS2 using chemical vapor deposition. By optimizing the growth conditions, spatially selective and heavy Nb doping was successfully achieved, resulting in a significant work function difference between the inner and edge regions of the single-crystalline MoS2, leading to n-type and degenerate p-type semiconductor behaviors along with clear rectifying behavior.
Article
Engineering, Electrical & Electronic
Jiawen Xiang, Wen Hsin Chang, Takuya Saraya, Toshiro Hiramoto, Toshifumi Irisawa, Masaharu Kobayashi
Summary: This study experimentally demonstrated the memory operation of a HfO2-based ferroelectric PET with an ultrathin MoS2 channel and bottom-gate structure. The ferroelectricity in HfZrO2 was enhanced through post-deposition anneal process with ZrO2 seed layer. The instability of the transistor characteristics was reduced by surface passivation of the MoS2 layer. By effectively controlling the body potential using an additional top gate, the FeFET memory operation was realized with enhanced ferroelectricity and body-potential control.
IEEE JOURNAL OF THE ELECTRON DEVICES SOCIETY
(2022)
Article
Chemistry, Multidisciplinary
Mitsuhiro Okada, Jiang Pu, Yung-Chang Lin, Takahiko Endo, Naoya Okada, Wen-Hsin Chang, Anh Khoa Augustin Lu, Takeshi Nakanishi, Tetsuo Shimizu, Toshitaka Kubo, Yasumitsu Miyata, Kazu Suenaga, Taishi Takenobu, Takatoshi Yamada, Toshifumi Irisawa
Summary: The control of crystal polymorphism and exploration of metastable, two-dimensional, 1T' phase, transition-metal dichalcogenides (TMDs) have been the focus of research due to their potential applications in various fields. However, the high energy difference and phase change barrier between 1T' and 2H phases make it difficult to obtain monolayer 1T' phase TMDs. In this study, we successfully grew 1T' phase WS2 atomic layers using chemical vapor deposition (CVD) with alkali metal assistance. The resulting high-quality crystals showed superconductivity and hold promise for applications such as quantum computing and energy storage devices. The alkali metal assisted gas-source CVD growth method provides a viable approach to realizing large-scale, high-quality TMD atomic layers.
Article
Physics, Applied
Tatsuro Maeda, Kazuaki Oishi, Hiroto Ishii, Hiroyuki Ishii, Wen Hsin Chang, Tetsuji Shimizu, Akira Endoh, Hiroki Fujishiro, Takashi Koida
Summary: In this study, the fabrication and investigation of Schottky barrier contact on n- and p-type In0.53Ga0.47As with transparent conductive oxide (TCO) that transmits light is presented. The contact shows explicit rectifying behavior and insertion of an ultra-thin Ni-layer reduces contact resistivity significantly. This contact has potential for broadband light detection in the optical communication band.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
Junichi Hattori, Koichi Fukuda, Tsutomu Ikegami, Wen Hsin Chang
Summary: This study investigates the static behavior of Ge-p/Si-n nanosheet CFETs and compares it with Si-p/Si-n nanosheet CFETs under temperature variations. It is found that the temperature rise has similar effects on the static characteristics of both CFETs operating as inverters, with slightly smaller variations in threshold voltage and noise margin for the Ge-p/Si-n CFET inverter compared to the Si-p/Si-n CFET inverter. The temperature rise effects are fully explained by the temperature dependence of material and carrier properties of Ge and Si.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Nanoscience & Nanotechnology
Wen Hsin Chang, Shogo Hatayama, Yuta Saito, Naoya Okada, Takahiko Endo, Yasumitsu Miyata, Toshifumi Irisawa
Summary: This work demonstrates the fabrication of atomically aligned van der Waals junctions through thermal-induced crystallization of layered Sb2Te3 electrodes on monolayer MoS2. The Sb2Te3/W contact shows better device performance on MoS2 MOSFETs compared to the Sb/W contact. The ideal vdW junctions exhibit extreme high-thermal robustness.
ADVANCED ELECTRONIC MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Yuta Saito, Shogo Hatayama, Wen Hsin Chang, Naoya Okada, Toshifumi Irisawa, Fumihiko Uesugi, Masaki Takeguchi, Yuji Sutou, Paul Fons
Summary: This article reports on the growth of thin crystalline films of the metastable phase GeTe2. Direct observation by transmission electron microscopy revealed a Te-Ge-Te stacking with van der Waals gaps. Moreover, electrical and optical measurements demonstrated that the films exhibited semiconducting properties suitable for electronic applications. Feasibility studies involving device structures also highlighted the potential of GeTe2 as an electronic material.
MATERIALS HORIZONS
(2023)
Article
Chemistry, Multidisciplinary
Vladimir Poborchii, Jesse Groenen, Pavel Geshev, Junichi Hattori, Wen Hsin Chang, Hiroyuki Ishii, Toshifumi Irisawa, Tatsuro Maeda
Summary: This study investigates the thickness dependencies of phonons and electrons in GeOI nanolayers, demonstrating the use of acoustic phonon Raman spectra for probing GeOI thickness above 5 nm. Limitations of confinement theories for GeOI thickness below 5 nm are attributed to increased influence of Ge-GeO2 interface disorder. The study also suggests that Al2O3 coating improves agreement between experimental and confinement theories by reducing disorder at the Ge-GeOx-Al2O3 interface, with potential benefits for modern and future nanoelectronic devices.
