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Toshio Kamiya

Bio: Toshio Kamiya is an academic researcher from Tokyo Institute of Technology. The author has contributed to research in topics: Amorphous solid & Thin film. The author has an hindex of 76, co-authored 383 publications receiving 38115 citations.


Papers
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Journal ArticleDOI
25 Nov 2004-Nature
TL;DR: A novel semiconducting material is proposed—namely, a transparent amorphous oxide semiconductor from the In-Ga-Zn-O system (a-IGZO)—for the active channel in transparent thin-film transistors (TTFTs), which are fabricated on polyethylene terephthalate sheets and exhibit saturation mobilities and device characteristics are stable during repetitive bending of the TTFT sheet.
Abstract: Transparent electronic devices formed on flexible substrates are expected to meet emerging technological demands where silicon-based electronics cannot provide a solution. Examples of active flexible applications include paper displays and wearable computers1. So far, mainly flexible devices based on hydrogenated amorphous silicon (a-Si:H)2,3,4,5 and organic semiconductors2,6,7,8,9,10 have been investigated. However, the performance of these devices has been insufficient for use as transistors in practical computers and current-driven organic light-emitting diode displays. Fabricating high-performance devices is challenging, owing to a trade-off between processing temperature and device performance. Here, we propose to solve this problem by using a novel semiconducting material—namely, a transparent amorphous oxide semiconductor from the In-Ga-Zn-O system (a-IGZO)—for the active channel in transparent thin-film transistors (TTFTs). The a-IGZO is deposited on polyethylene terephthalate at room temperature and exhibits Hall effect mobilities exceeding 10 cm2 V-1 s-1, which is an order of magnitude larger than for hydrogenated amorphous silicon. TTFTs fabricated on polyethylene terephthalate sheets exhibit saturation mobilities of 6–9 cm2 V-1 s-1, and device characteristics are stable during repetitive bending of the TTFT sheet.

7,301 citations

Journal ArticleDOI
23 May 2003-Science
TL;DR: The fabrication of transparent field-effect transistors using a single-crystalline thin-film transparent oxide semiconductor, InGaO3(ZnO)5, as an electron channel and amorphous hafnium oxide as a gate insulator provides a step toward the realization of transparent electronics for next-generation optoelectronics.
Abstract: We report the fabrication of transparent field-effect transistors using a single-crystalline thin-film transparent oxide semiconductor, InGaO 3 (ZnO) 5 , as an electron channel and amorphous hafnium oxide as a gate insulator. The device exhibits an on-to-off current ratio of ∼10 6 and a field-effect mobility of ∼80 square centimeters per volt per second at room temperature, with operation insensitive to visible light irradiation. The result provides a step toward the realization of transparent electronics for next-generation optoelectronics.

2,724 citations

Journal ArticleDOI
TL;DR: In this paper, a-IGZO is used as the channel layer for flexible and transparent TFTs. But, the performance of the flexible TFT was evaluated at room temperature and at temperatures up to 500 °C.
Abstract: Recently, we have demonstrated the potential of amorphous oxide semiconductors (AOSs) for developing flexible thin-film transistors (TFTs). A material exploration of AOSs desired as the channel layer in TFTs is most important for developing high-performance devices. Here, we report our concept of material exploration for AOSs in high-performance flexible and transparent TFTs from the viewpoints of chemical bonding and electronic structure in oxide semiconductors. We find that amorphous In–Ga–Zn–O (a-IGZO) exhibits good carrier transport properties such as reasonably high Hall mobilities (>10 cm2V-1s-1) and a good controllability of carrier concentration from <1015 to 1020 cm-3. In addition, a-IGZO films have better chemical stabilities in ambient atmosphere and at temperatures up to 500 °C. The flexible and transparent TFT fabricated using a-IGZO channel layer at room temperature operated with excellent performances, such as normally-off characteristics, on/off current ratios (~106) and field-effect mobilities (~10 cm2V-1s-1), which are higher by an order of magnitude than those of amorphous Si:H and organics TFTs.

1,634 citations

Journal ArticleDOI
TL;DR: Most device issues, such as uniformity, long-term stability against bias stress and TFT performance, are solved for a-IGZO TFTs.

1,573 citations

Journal ArticleDOI
TL;DR: Magnetic and electrical resistivity measurements verify the occurrence of the superconducting transition at approximately 4 K in an iron-based layered oxy-pnictide LaOFeP.
Abstract: We report superconductivity in an iron-based layered oxy-pnictide LaOFeP. LaOFeP is composed of an alternate stack of lanthanum oxide (La3+O2-) and iron pnictide (Fe2+P3-) layers. Magnetic and electrical resistivity measurements verify the occurrence of the superconducting transition at ∼4 K.

1,399 citations


Cited by
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Journal ArticleDOI

[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

Journal ArticleDOI
TL;DR: The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60meV) which could lead to lasing action based on exciton recombination even above room temperature.
Abstract: The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60meV) which could lead to lasing action based on exciton recombination even above room temperature. Even though research focusing on ZnO goes back many decades, the renewed interest is fueled by availability of high-quality substrates and reports of p-type conduction and ferromagnetic behavior when doped with transitions metals, both of which remain controversial. It is this renewed interest in ZnO which forms the basis of this review. As mentioned already, ZnO is not new to the semiconductor field, with studies of its lattice parameter dating back to 1935 by Bunn [Proc. Phys. Soc. London 47, 836 (1935)], studies of its vibrational properties with Raman scattering in 1966 by Damen et al. [Phys. Rev. 142, 570 (1966)], detailed optical studies in 1954 by Mollwo [Z. Angew. Phys. 6, 257 (1954)], and its growth by chemical-vapor transport in 1970 by Galli and Coker [Appl. Phys. ...

10,260 citations

Journal ArticleDOI
25 Nov 2004-Nature
TL;DR: A novel semiconducting material is proposed—namely, a transparent amorphous oxide semiconductor from the In-Ga-Zn-O system (a-IGZO)—for the active channel in transparent thin-film transistors (TTFTs), which are fabricated on polyethylene terephthalate sheets and exhibit saturation mobilities and device characteristics are stable during repetitive bending of the TTFT sheet.
Abstract: Transparent electronic devices formed on flexible substrates are expected to meet emerging technological demands where silicon-based electronics cannot provide a solution. Examples of active flexible applications include paper displays and wearable computers1. So far, mainly flexible devices based on hydrogenated amorphous silicon (a-Si:H)2,3,4,5 and organic semiconductors2,6,7,8,9,10 have been investigated. However, the performance of these devices has been insufficient for use as transistors in practical computers and current-driven organic light-emitting diode displays. Fabricating high-performance devices is challenging, owing to a trade-off between processing temperature and device performance. Here, we propose to solve this problem by using a novel semiconducting material—namely, a transparent amorphous oxide semiconductor from the In-Ga-Zn-O system (a-IGZO)—for the active channel in transparent thin-film transistors (TTFTs). The a-IGZO is deposited on polyethylene terephthalate at room temperature and exhibits Hall effect mobilities exceeding 10 cm2 V-1 s-1, which is an order of magnitude larger than for hydrogenated amorphous silicon. TTFTs fabricated on polyethylene terephthalate sheets exhibit saturation mobilities of 6–9 cm2 V-1 s-1, and device characteristics are stable during repetitive bending of the TTFT sheet.

7,301 citations

Journal ArticleDOI
TL;DR: It is reported that a layered iron-based compound LaOFeAs undergoes superconducting transition under doping with F- ions at the O2- site and exhibits a trapezoid shape dependence on the F- content.
Abstract: We report that a layered iron-based compound LaOFeAs undergoes superconducting transition under doping with F- ions at the O2- site. The transition temperature (Tc) exhibits a trapezoid shape dependence on the F- content, with the highest Tc of ∼26 K at ∼11 atom %.

6,643 citations

Journal ArticleDOI
TL;DR: In this article, the authors present a comprehensive, up-to-date compilation of band parameters for the technologically important III-V zinc blende and wurtzite compound semiconductors.
Abstract: We present a comprehensive, up-to-date compilation of band parameters for the technologically important III–V zinc blende and wurtzite compound semiconductors: GaAs, GaSb, GaP, GaN, AlAs, AlSb, AlP, AlN, InAs, InSb, InP, and InN, along with their ternary and quaternary alloys. Based on a review of the existing literature, complete and consistent parameter sets are given for all materials. Emphasizing the quantities required for band structure calculations, we tabulate the direct and indirect energy gaps, spin-orbit, and crystal-field splittings, alloy bowing parameters, effective masses for electrons, heavy, light, and split-off holes, Luttinger parameters, interband momentum matrix elements, and deformation potentials, including temperature and alloy-composition dependences where available. Heterostructure band offsets are also given, on an absolute scale that allows any material to be aligned relative to any other.

6,349 citations