Article
Nanoscience & Nanotechnology
Daisuke Ohori, Takahiro Ishihara, Xuelun Wang, Kazuhiko Endo, Tsou-Hwa Hsieh, Yiming Li, Nobuhiro Natori, Kazuma Matsui, Seiji Samukawa
Summary: In this study, the etching characteristics of hydrogen iodide (HI) neutral beam etching (NBE) of GaN and InGaN were investigated and compared with Cl-2 NBE. The advantages of HI NBE over Cl-2 NBE were demonstrated, including higher InGaN etch rate, better surface smoothness, and reduced etching residues. It was found that HI NBE had higher reactivity with In, resulting in higher InGaN etch rates and thinner reaction layers. Additionally, HI NBE suppressed defect generation and yellow luminescence intensity increase after etching. Therefore, HI NBE shows potential for high throughput fabrication of micro LEDs.
Article
Computer Science, Information Systems
Tingting Jin, Jiajie Lin, Tiangui You, Xiaolei Zhang, Hao Liang, Yifan Zhu, Jialiang Sun, Hangning Shi, Chaodan Chi, Min Zhou, Robert Kudrawiec, Shumin Wang, Xin Ou
Summary: This study successfully achieved the transfer of InP and GaSb thin films onto Si substrates using molecular beam epitaxy and the ion-slicing technique combined with selective chemical etching. The sacrificial layers were completely etched off, leaving high-quality and ultra-smooth epitaxial surfaces without the need for chemical mechanical polishing. This method provides a sustainable and cost-effective approach for Si integration.
SCIENCE CHINA-INFORMATION SCIENCES
(2022)
Article
Chemistry, Multidisciplinary
Vladimir A. Zinovyev, Zhanna V. Smagina, Aigul F. Zinovieva, Aleksei A. Bloshkin, Anatoly V. Dvurechenskii, Ekaterina E. Rodyakina, Margarita V. Stepikhova, Artem V. Peretokin, Alexey V. Novikov
Summary: The effects of resonance interaction between plasmonic and photonic modes in hybrid metal-dielectric structures with square Al nanodisk lattices coupled with a Si waveguide layer were investigated using micro-photoluminescence spectroscopy. GeSi quantum dots embedded in the waveguide served as radiation sources. Narrow photoluminescence peaks superimposed on broad bands were observed within the range of quantum dot emissions. By optimizing the parameters of the Al nanodisk lattices, the photoluminescence intensity increased by almost one order. The experimental results matched well with the theoretical calculations, confirming the realization of high-quality bound states in the continuum. These structures demonstrated potential for achieving a flat band and supporting slow light.
Article
Materials Science, Multidisciplinary
Moqiang Guo, Yuanshen Huang, Bin Sheng, Banglian Xu, Yuhang Shen, Mengjing Xu, Minghao Gao
Summary: This work presents a large area and high precision neutral density filter made of Ni80Cr20, with a manufacturing method for controlling film thickness. The use of low energy ion beams on the membrane surface enables the control of optical density with an absolute error within 0.01 and a relative error of +/- 2%, resulting in a much better accuracy compared to existing commercial filters. Additionally, a neutral density filter with 18 steps is produced for use as a component in a spectral sensitivity spectrometer.
Article
Nanoscience & Nanotechnology
Gyo Wun Kim, Won Jun Chang, Ji Eun Kang, Hee Ju Kim, Geun Young Yeom
Summary: This study compared the radiation damage to EUV resist during etching of hardmask materials using CF4 gas between neutral beam etching (NBE) and ion beam etching (IBE). The results showed that NBE reduced the line edge roughness increase and critical dimension change of EUV resist compared to IBE. NBE also had a lower root mean square surface roughness value of EUV resist and higher etch selectivity for materials such as Si3N4 and SiO2 over EUV resist.
Article
Chemistry, Multidisciplinary
Mohammad S. Almomani, Naser M. Ahmed, Marzaini Rashid, M. K. M. Ali, H. Akhdar, O. Aldaghri, K. H. Ibnaouf
Summary: This study successfully fabricated high-brightness ZnO-incorporated Zinc@Silicon core-shell quantum dots with customized properties and enhanced their absorption and emission efficiency by controlling the NH4OH content, showing significant improvements in morphology and optical characteristics.
Article
Nanoscience & Nanotechnology
Yeonhwa Kim, Rafael Jumar Chu, Geunhwan Ryu, Seungwan Woo, Quang Nhat Dang Lung, Dae-Hwan Ahn, Jae-Hoon Han, Won Jun Choi, Daehwan Jung
Summary: By reducing the thickness of the GaAs buffer and inserting an Al0.4Ga0.6As electron barrier layer, photoluminescence enhancement of QDs can be achieved, leading to the fabrication of efficient light-emitting diodes on a silicon substrate.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Chemistry, Physical
Sudip Bhowmick, Joy Mukherjee, Biswarup Satpati, Prasanta Karmakar
Summary: Isolated silver nano-dot formation on pre-patterned silicon nitride nano templates using ion bombardment was reported. The presence of the Ag dots significantly enhanced the Raman signal, with a change in light reflectance observed on the surface. The study described the growth mechanism of pyramidal structures by ion bombardment and the process of isolated Ag dot formation.
APPLIED SURFACE SCIENCE
(2022)
Article
Chemistry, Physical
Anindita Deka, Pintu Barman, M. K. Mukhopadhyay, S. R. Bhattacharyya
Summary: This study investigates the impact of surface patterning in nano-scale dimension on the wettability of solid surfaces, particularly focusing on the generation of Si nano-patterns at oblique incidence. The addition of stainless steel as seeding material during bombardment leads to a significant change in surface topography, transitioning from ripple morphology to hillocks structures. The evolution from nano-ripple to nano-hillock pattern is influenced by FeSi2 bond, resulting in increased surface hydrophobicity.
SURFACES AND INTERFACES
(2021)
Article
Engineering, Electrical & Electronic
Zhitian Shi, Konstantins Jefimovs, Marco Stampanoni, Lucia Romano
Summary: This paper introduces a method for realizing protruding sharp silicon nanopillar arrays by using displacement Talbot lithography combined with metal-assisted chemical etching in the gas phase. This combination allows for reliable and low-cost fabrication of large-scale ordered nanopillar arrays. Incorporating controlled uniformity of feature size, spatial frequency doubling, and high resolution of Talbot lithography, this proposed method provides an easy-to-scale-up processing for producing silicon pillar arrays for valuable applications in both micro and nano scales.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2023)
Article
Physics, Applied
Min-Hui Chuang, Yiming Li, Seiji Samukawa
Summary: The study focuses on the impact of geometry effects on the energy band of well-aligned silicon nanopillars in a silicon-germanium matrix, with emphasis on the crucial role of nanopillar separation in manipulating the band structure.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2021)
Article
Green & Sustainable Science & Technology
M. K. Shreya, C. Indhumathi, G. R. Rajarajeswari, Veeramuthu Ashokkumar, T. Preethi
Summary: The usage of templates in synthesizing titania can increase surface area and shift absorption edge to visible range effectively. Green synthesis using bio-waste as templates for nano-titania synthesis has gained substantial attention as an effective approach for photocatalytic applications.
CLEAN TECHNOLOGIES AND ENVIRONMENTAL POLICY
(2021)
Article
Chemistry, Physical
Dmitry Rogilo, Sergey Sitnikov, Sergey Ponomarev, Dmitry Sheglov, Liudmila Fedina, Alexander Latyshev
Summary: Through in situ reflection electron microscopy and ex situ atomic force microscopy, the research investigated the morphological stability of large-scale Si(111)-7x7 terraces during silicon growth and etching by oxygen and selenium. The study identified three modes of morphological instability, with oxygen etching leading to slow multilayer development and selenium-induced etching preserving flat surface morphology with periodic 2D vacancy island formation. Additionally, on step-bunched surfaces, Si or Se adatom diffusion to step bunches results in self-organized pyramidlike or valley-like morphology during Si growth or Se-induced etching.
APPLIED SURFACE SCIENCE
(2021)
Article
Chemistry, Physical
Pan Tian, Zhongjie Cai, Guowu Zhan, Jiale Huang, Qingbiao Li
Summary: Using acid-etched pollen as a template, bio-In2O3/Pd catalysts were efficiently prepared and exhibited excellent performance in CO2 hydrogenation to methanol, showing a significant enhancement due to the unique structure and surface functional groups of the acid-etched pollen template.
MOLECULAR CATALYSIS
(2021)
Article
Chemistry, Physical
David W. Collinson, Dhriti Nepal, Jarrett Zwick, Reinhold H. Dauskardt
Summary: Atomic force microscopy (AFM) is a valuable tool for studying composite surfaces. However, its application is limited by the smoothness and damage-free requirement of sample surfaces. This study demonstrates the effective use of gas cluster ion beam (GCIB) etching for preparing composite materials, enabling high-resolution AFM analysis.
APPLIED SURFACE SCIENCE
(2022)
Article
Electrochemistry
Kyung Ho Kim, Mei Kahuku, Yoshio Abe, Midori Kawamura, Takayuki Kiba
INTERNATIONAL JOURNAL OF ELECTROCHEMICAL SCIENCE
(2020)
Article
Nanoscience & Nanotechnology
Firman Mangasa Simanjuntak, Takeo Ohno, Sridhar Chandrasekaran, Tseung-Yuen Tseng, Seiji Samukawa
Article
Physics, Applied
Min-Hui Chuang, Yiming Li, Seiji Samukawa
Summary: The study focuses on the impact of geometry effects on the energy band of well-aligned silicon nanopillars in a silicon-germanium matrix, with emphasis on the crucial role of nanopillar separation in manipulating the band structure.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2021)
Article
Materials Science, Coatings & Films
Sou Takeuchi, Daisuke Ohori, Masahiro Sota, Teruhisa Ishida, Yiming Li, Jenn-Hwan Tarng, Kazuhiko Endo, Seiji Samukawa
Summary: By combining biotemplate and neutral beam etching processes, we fabricated high aspect ratio Si nanopillar arrays to investigate the wettability with and without surface silicon oxide film. The presence of silicon native oxides in the gaps resulted in super-hydrophilicity, while selectively removing the oxides led to high hydrophobicity in the Si nanopillars. This study demonstrates the controllable surface wettability achieved by manipulating the gap sizes and the presence of silicon native oxides on the surfaces.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2021)
Article
Materials Science, Coatings & Films
Daisuke Ohori, Takahiro Sawada, Kenta Sugawara, Masaya Okada, Ken Nakata, Kazutaka Inoue, Daisuke Sato, Seiji Samukawa
Summary: The study focused on investigating higher selective etching between SiN and GaN using an HBr neutral beam, which showed a more selective reaction compared to Cl-2 NB. The etching rate of GaN was found to be drastically decreased at the atomic layer level with HBr NB due to the lower vapor pressure of the etching product GaBrx. Additionally, the neutral beam energy dependence of the surface reaction layer of SiN was larger in HBr NB, leading to improved etching selectivity between SiN and GaN.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2021)
Article
Materials Science, Multidisciplinary
Takayuki Kiba, Kazuaki Masui, Yuuki Inomata, Atsushi Furumoto, Midori Kawamura, Yoshio Abe, Kyung Ho Kim
Summary: Ag thin-films of various thicknesses were deposited using thermal vacuum evaporation and subsequently annealed to form Ag nanoparticles, with the size of the nanoparticles increasing as the initial Ag deposition thickness increased. The red-shift of the extinction peak of Ag nanoparticles was observed, indicating localized surface plasmon resonance. Coating the organic emitter film on Ag nanoparticles led to a significant enhancement of photoluminescence, showing potential for improving the light-extraction efficiency of organic light-emitting devices.
Article
Materials Science, Coatings & Films
Beibei Ge, Daisuke Ohori, Yi-Ho Chen, Takuya Ozaki, Kazuhiko Endo, Yiming Li, Jenn-Hwan Tarng, Seiji Samukawa
Summary: This study reports the fabrication of high-quality hafnium dioxide (HfO2) film using neutral beam enhanced atomic layer deposition (NBEALD) at room temperature. The film exhibited excellent properties with low contamination and ideal refractive index. Additionally, high-quality stacked HfO2/SiO2 gate oxide films were successfully fabricated at room temperature.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2022)
Article
Chemistry, Multidisciplinary
Naoya Satoh, Tsubasa Tanno, Takuya Kitabayashi, Takayuki Kiba, Midori Kawamura, Yoshio Abe
Summary: This study demonstrates the use of CaF2/ZnS multilayered films to protect and improve the performance of organic light-emitting diodes (OLEDs), resulting in a sustained and stable emitting area.
Article
Physics, Applied
Firman Mangasa Simanjuntak, Takeo Ohno, Kana Minami, Seiji Samukawa
Summary: A Cu/ZnO/ITO resistive random access memory (RRAM) structure was employed to investigate the effect of neutral oxygen beams as a surface treatment on ZnO films. The treatment reduced defect concentration in the sputtered-ZnO film and improved the resistance change characteristics of the device. These results indicate the great potential of neutral oxygen beams in the development of RRAM devices using ZnO films.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Roman Anufriev, Daisuke Ohori, Yunhui Wu, Ryoto Yanagisawa, Laurent Jalabert, Seiji Samukawa, Masahiro Nomura
Summary: The high thermal conductivity of silicon limits the performance of silicon-based thermoelectric energy generators. Past theoretical works proposed reducing the thermal conductivity with nanopillars on silicon films. However, due to difficulties in nanofabrication and measurements, these predictions were never confirmed. In this work, we fabricated and measured silicon films with nanopillars as small as 12 nm in diameter. Our experiments showed that nanopillars do host resonant phonon modes, but thermal measurements revealed no significant difference compared to silicon membranes without nanopillars. These results contradict previous predictions, suggesting the need for refined simulations under realistic experimental conditions.
Article
Physics, Applied
Tomoki Harada, Daisuke Ohori, Kazuhiko Endo, Seiji Samukawa, Tetsuo Ikari, Atsuhiko Fukuyama
Summary: Thermal management is crucial for miniaturized semiconductor devices. In metal-oxide-semiconductor field-effect transistors, temperature rise due to heat generation can reduce electron mobility. By inserting nanostructures into the channel layer, temperature rise can be prevented and electron mobility can be maintained. The effect of nanostructure spacing on heat generation and carrier behavior of Si-NP/SiGe composite films was studied. The carrier lifetime was found to increase when the nanostructure spacing was comparable to the electron mean-free path.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Energy & Fuels
Aditya Saha, Ryuji Oshima, Daisuke Ohori, Takahiko Sasaki, Hirokazu Yano, Hidenori Okuzaki, Takashi Tokumasu, Kazuhiko Endo, Seiji Samukawa
Summary: PEDOT:PSS/Si hybrid photovoltaic cells are attracting attention as a simplified and democratized way of solar energy production. The control of the PEDOT/Si interface is crucial for improved performance and lifetimes of multijunction devices. The effects of the interfacial silicon oxide layer were investigated, and it was found that saturated interfacial silicon atoms and a thin, damage-free oxide interlayer were key for maintaining good passivation and high tunneling current. The interlayers with higher SiO2 content showed the least degradation.
Article
Nanoscience & Nanotechnology
Yi-Ho Chen, Daisuke Ohori, Muhammad Aslam, Yao-Jen Lee, Yiming Li, Seiji Samukawa
Summary: This study investigated the electrical properties of AlGaN/GaN high-electron-mobility transistors (HEMTs) with varied recess depths under the gate electrode. It was found that a recess depth of approximately 6 nm achieved through neutral beam etching (NBE) technique resulted in device enhancement-mode (E-mode) behavior with a threshold voltage (V-th) of 0.49 V. The study also examined the effects of post-metallization annealing (PMA) on device performance, showing improvements in various DC characteristics.
IEEE OPEN JOURNAL OF NANOTECHNOLOGY
(2023)
Article
Nanoscience & Nanotechnology
Seiji Samukawa
Summary: This paper reviews the author's work on a neutral beam process that suppresses the formation of defects at the atomic layer level, allowing for ideal surface chemical reactions to occur at room temperature. This technology is of great importance for creating innovative nano-devices in the future.
IEEE OPEN JOURNAL OF NANOTECHNOLOGY
(2022)
Article
Nanoscience & Nanotechnology
Daisuke Ohori, Takuya Fujii, Shuichi Noda, Wataru Mizubayashi, Kazuhiko Endo, Yao-Jen Lee, Jenn-Hwan Tarng, Yiming Li, Seiji Samukawa
Summary: The study found that a high electron mobility Ge FinFET fabricated by defect-free and atomically-flat NBE showed significantly better surface roughness and defect generation compared to conventional PE. NBE can greatly improve the electron mobility of Ge FinFET, enhance the interface defect density, and reduce leakage current to a lower level.
IEEE OPEN JOURNAL OF NANOTECHNOLOGY
(2021)
