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Akihisa Matsuda

Other affiliations: Tokyo University of Science
Bio: Akihisa Matsuda is an academic researcher from National Institute of Advanced Industrial Science and Technology. The author has contributed to research in topics: Amorphous silicon & Silicon. The author has an hindex of 45, co-authored 288 publications receiving 7163 citations. Previous affiliations of Akihisa Matsuda include Tokyo University of Science.


Papers
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Journal ArticleDOI
TL;DR: In this article, a high rate growth method of microcrystalline silicon at low temperatures has been developed using plasma enhanced chemical vapor deposition (PECVD) using a novel control of plasma is demonstrated using a high deposition pressure of 2-4 Torr combined with a depletion condition of source gas (SiH 4 ) at a high RF power (a high-pressure-depletion method) and consequently a growth rate of 1.5 nm/s has been achieved using a conventional radio frequency plasma enhanced chemically vapor deposition at 13.56 MHz.
Abstract: A high rate growth method of microcrystalline silicon at low temperatures has been developed using plasma enhanced chemical vapor deposition (PECVD). It has been found that energetic positive ion and atomic hydrogen impingement on to a growing surface have important affects and that atomic hydrogen density needs to increase correspondingly to the increasing growth rate, while keeping ion bombardment less. Based on this guide line, a novel control of plasma is demonstrated using a high deposition pressure of 2–4 Torr combined with a depletion condition of source gas (SiH 4 ) at a high RF power (a high-pressure-depletion method) and consequently a growth rate of 1.5 nm/s has been achieved using a conventional radio frequency plasma enhanced chemical vapor deposition at 13.56 MHz. Use of a very high frequency plasma at 60 MHz further increases the growth rate up to 5 nm/s and good crystallinity is maintained up to 3.8 nm/s at 250°C. Atomic hydrogen-mediated growth of crystalline silicon at low temperatures is discussed.

285 citations

Journal ArticleDOI
TL;DR: In this paper, the process used to grow hydrogenated microcrystalline silicon (μc-Si:H) from a H 2 /SiH 4 -glow discharge plasma is explained in comparison to those for hydrogenated amorphous silicon (a-Si-H).
Abstract: Processes used to grow hydrogenated microcrystalline silicon (μc-Si:H) from a H 2 /SiH 4 -glow discharge plasma are explained in comparison to those for hydrogenated amorphous silicon (a-Si:H). Differences and similarities between μc-Si:H and a-Si:H-growth reactions in the plasma and on the film-growing surface are discussed, and the nucleus-formation process followed by epitaxial-like crystal growth process is illustrated as unique processes for the formulation of μc-Si:H. Determination of the effect of dangling-bond defect density on the propagation of the resulting μc-Si:H films is also discussed in parallel with the effect on a-Si:H in order to obtain a clue to improve opto-electronic properties of those materials for device applications especially for thin-film-silicon solar cells. Material issues to produce low cost and high efficiency solar cells are described, and finally recent progress in those issues is demonstrated.

267 citations

Journal ArticleDOI
TL;DR: In this paper, the sticking probability and total loss probability of silyl (SiH 3 ) radicals on the growing surface of hydrogenated amorphous silicon (a-Si : H) were determined from deposition, step-coverage in a trench structure on a c-Si wafer, and determination of β using a grid system.

231 citations

Journal ArticleDOI
TL;DR: In this article, a radiofrequency plasma-enhanced chemical vapor deposition method was used for the deposition of hydrogenated microcrystalline silicon (µc-Si:H) at a relatively high working pressure.
Abstract: The deposition of hydrogenated microcrystalline silicon (µc-Si:H) at a relatively high working pressure is performed using a conventional radio-frequency plasma-enhanced chemical vapor deposition method. Correlation of the deposition rate and crystallinity with deposition parameters, such as working pressure, flow rate, dilution ratio and input RF power, are studied. It was found that the deposition rate exhibits a maximum at around 4 Torr and that the crystallinity of films decreases monotonically with increasing pressure. The combination of SiH4 depletion and high working pressure in the plasma is necessary to improve the crystallinity of films deposited at a high rate. Consequently, a high deposition rate of 9.3 A/s is achieved with high crystallinity and low defect density.

207 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, the piezoelectric properties of relaxor based ferroelectric single crystals, such as Pb(Zn1/3Nb2/3)O3 and PbTiO3, were investigated for electromechanical actuators.
Abstract: The piezoelectric properties of relaxor based ferroelectric single crystals, such as Pb(Zn1/3Nb2/3)O3–PbTiO3 and Pb(Mg1/3Nb2/3)O3–PbTiO3 were investigated for electromechanical actuators. In contrast to polycrystalline materials such as Pb(Zr,Ti)O3, morphotropic phase boundary compositions were not essential for high piezoelectric strain. Piezoelectric coefficients (d33’s)>2500 pC/N and subsequent strain levels up to >0.6% with minimal hysteresis were observed. Crystallographically, high strains are achieved for 〈001〉 oriented rhombohedral crystals, although 〈111〉 is the polar direction. Ultrahigh strain levels up to 1.7%, an order of magnitude larger than those available from conventional piezoelectric and electrostrictive ceramics, could be achieved being related to an E-field induced phase transformation. High electromechanical coupling (k33)>90% and low dielectric loss <1%, along with large strain make these crystals promising candidates for high performance solid state actuators.

3,766 citations

Journal ArticleDOI
TL;DR: It is shown how to use resonant Raman spectroscopy to determine structure and composition of carbon films with and without nitrogen, and the assignment of the peaks at 1150 and 1480 cm−1 often observed in nanodiamond.
Abstract: Raman spectroscopy is a standard characterization technique for any carbon system. Here we review the Raman spectra of amorphous, nanostructured, diamond-like carbon and nanodiamond. We show how to use resonant Raman spectroscopy to determine structure and composition of carbon films with and without nitrogen. The measured spectra change with varying excitation energy. By visible and ultraviolet excitation measurements, the G peak dispersion can be derived and correlated with key parameters, such as density, sp(3) content, elastic constants and chemical composition. We then discuss the assignment of the peaks at 1150 and 1480 cm(-1) often observed in nanodiamond. We review the resonant Raman, isotope substitution and annealing experiments, which lead to the assignment of these peaks to trans-polyacetylene.

2,172 citations

Patent
01 Aug 2008
TL;DR: In this article, the oxide semiconductor film has at least a crystallized region in a channel region, which is defined as a region of interest (ROI) for a semiconductor device.
Abstract: An object is to provide a semiconductor device of which a manufacturing process is not complicated and by which cost can be suppressed, by forming a thin film transistor using an oxide semiconductor film typified by zinc oxide, and a manufacturing method thereof. For the semiconductor device, a gate electrode is formed over a substrate; a gate insulating film is formed covering the gate electrode; an oxide semiconductor film is formed over the gate insulating film; and a first conductive film and a second conductive film are formed over the oxide semiconductor film. The oxide semiconductor film has at least a crystallized region in a channel region.

1,501 citations

Journal ArticleDOI
TL;DR: In this paper, the technical progress made in the past several years in the area of mono- and polycrystalline thin-film photovoltaic (PV) technologies based on Si, III-V, II-VI, and I-III-VI2 semiconductors, as well as nano-PV.

914 citations

Journal ArticleDOI
TL;DR: In this paper, a chemical bonding model is developed which describes the arrangement of these sites and which accounts for many of the electronic and mechanical properties of amorphous carbon, including elastic modulus, hardness, wear rate, friction and film adhesion.

683 citations