A5026366957- Semiconductor materials and interfaces
- Silicon and Solar Cell Technologies
- Semiconductor materials and devices
- Advancements in Semiconductor Devices and Circuit Design
- Semiconductor Quantum Structures and Devices
- Integrated Circuits and Semiconductor Failure Analysis
- Nanowire Synthesis and Applications
- Thin-Film Transistor Technologies
- Silicon Nanostructures and Photoluminescence
- Advanced Materials Characterization Techniques
- Advanced Surface Polishing Techniques
- Surface and Thin Film Phenomena
- Chalcogenide Semiconductor Thin Films
- nanoparticles nucleation surface interactions
- Intermetallics and Advanced Alloy Properties
- Crystallization and Solubility Studies
- Advanced Electron Microscopy Techniques and Applications
- Silicon Carbide Semiconductor Technologies
- X-ray Diffraction in Crystallography
- GaN-based semiconductor devices and materials
- Photonic and Optical Devices
- Quantum Dots Synthesis And Properties
- Electron and X-Ray Spectroscopy Techniques
- Force Microscopy Techniques and Applications
- Structural Analysis and Optimization
University of Yamanashi
2015-2024
Christchurch Clinical Studies Trust
2021
Niigata University
2018-2019
Takeda (Japan)
2018
Nagoya University
2016
University of Tsukuba
2016
The University of Tokyo
1998-2003
In order to control the electrical properties of an evaporated BaSi2 film, which is emerging candidate for absorber-layer material earth-abundant thin-film solar cells, we have investigated effects deposition rate on produced phases, microstructure, and carrier density thin films grown by thermal evaporation BaSi2. X-ray diffraction results show that a high substrate temperature necessary formation at rate, discussed from viewpoints vapor composition diffusion time. Microstructural...
Abstract BaSi2 has suitable optoelectronic properties for solar cells, with a limiting efficiency of over 30% under one sun condition. However, its high reactivity often hinders heterojunction or heterostructure formation other materials property analysis and device fabrication. Here, we demonstrate the effectiveness MgO Sm2O3 interlayers by synthesizing films on fused silica substrates using two evaporation-based techniques: machine learning-assisted thermal evaporation close-spaced...
We fabricated high-quality strain-relaxed thin SiGe layers by Ar ion implantation into Si substrates before epitaxial growth. The surface of 100-nm-thick Si0.8Ge0.2 layers, the relaxation ratio which was more than 80%, found to be very smooth, with a rms roughness 0.34 nm. Cross-sectional transmission electron microscopy analysis confirmed that strain-relieving dislocations were effectively generated due ion-implantation-induced defects and confined in vicinity heterointerface, resulting...
We fabricated and studied nickel germanide (NiGe) contacts on both n- p-type germanium (Ge) substrates by applying the carrier activation enhancement (CAE) technique. achieved a high electron concentration of 8.6 × 10 19 cm −3 using P/Sb co-implant record-high hole 8.4 20 Ge preamorphization implant boron implant. used circular transfer length method two-dimensional DC simulation to determine specific contact resistivity (ρ c ). Using CAE technique, we obtained low ρ values 6.4 −7 Ω 2 for...
Thermal evaporation is a simple and rapid method to fabricate semiconducting BaSi2 films. In this study, elucidate the formation mechanism, microstructure of epitaxial film fabricated by thermal has been investigated transmission electron microscopy. The found consist three layers with different microstructural characteristics, which well explained assuming two stages deposition. first stage, forms through diffusion Ba atoms from deposited Ba-rich Si substrate while in second mutual leads...
Strain dependence of hole effective mass (m∗) in the strained Ge channel was systematically studied, and monotonic m∗ reduction by more than 20% clearly observed when strain increased from 0.8% up to 2.8%. The scattering mechanism, which strongly depended on modulation-doping structure as well strains, also investigated based Dingle ratio evaluation, interface roughness found be effectively suppressed adopting inverted even for largely channels.
The Ge composition dependence of the densities and energy levels acceptorlike defect states that are generated during solid-source molecular beam epitaxy (SSMBE) SiGe films was investigated. Hall measurements in a wide temperature range were carried out, previously unreported very shallow state found. We provide evidence observed relevant to intrinsic point defects.
Thermal evaporation is a useful method for the deposition of high-quality photovoltaic BaSi2 films. The elemental processes film formation are, however, complicated due to vapor composition change during evaporation. In this study, we thermodynamically calculate quantitative explanation process. Ba and Si fluxes are calculated from relative partial molar enthalpies in Ba–Si melt. Calculations show tendency decreasing flux increasing with mole fraction melt, by which being Ba-rich Si-rich...
Mechanical activation of a BaAl 4 –Ni source lowers the synthesis temperature BaSi 2 films in close-spaced evaporation from 1000 to 700 °C. The produced are free cracks and clearly show photoconductance.
A cylindrical tool was applied for ultrasonic bonding of multi-layered copper foil and a sheet to prevent damage the during bonding. The strength joints bonded with comparable that conventional knurled tool. effect surface on bondability investigated thorough relative motion behaviors between materials, as well bond microstructure evolution. visualized in-situ observation using high-speed camera digital image correlation. At shorter times, motions occurred at interfaces sheet. Thereafter,...
Heterojunction of p-type SnS and n-type BaSi2 is a promising structure for solar cell applications. In this study, we attempted to fabricate SnS/BaSi2 heterojunctions by thermal evaporation postannealing. Microstructure composition analyses reveal that when layers are formed at 650 ◦C 250 ◦C, which suitable single films, the layer porous interface oxygen concentration high. Postannealing 400 found effective densify layer. Combining low-temperature depositions 150 with postannealing succeeded...
A selective-ion-implantation technique was developed for introducing uniaxial strain into Si/Ge heterostructures. Laterally selective ion implantation with a stripe pattern carried out Si substrate, followed by SiGe overgrowth in the whole region. Large relaxation of occurred selectively only ion-implanted area. This largely relaxed found to considerably affect state neighboring strained unimplanted area, resulting realization highly asymmetric state, that is, strain. result indicates this...
We systematically studied on ion dose, energy, and species dependencies of strain relaxation ratios for SiGe buffer layers fabricated by implantation technique where the epitaxial growth was carried out Si or Ar preimplanted substrates. For Si+ implantation, we found that there an optimal ion-implantation condition to effectively enhance layers, is, increased with dose but reduced remarkably when it exceeded a certain critical (∼1×1015 cm−2). The drop also occurred as energy increased. Based...