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 …

I and i

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. ...

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A comprehensive review of zno materials and devices

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.

Room-temperature fabrication of transparent flexible thin-film transistors using amorphous oxide semiconductors

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 %.

Iron-Based Layered Superconductor La[O1-xFx]FeAs (x = 0.05−0.12) with Tc = 26 K

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.

Band parameters for III–V compound semiconductors and their alloys

12CaO7Al2O3 (C12A7) has a unique crystal structure composed of subnanometer-sized cages and free oxygen ions in the cages. C12A7 exhibits a variety of active functions if the free oxygen ions are substituted with other active anions. Electronic conduction was attained by introducing high-density F+-like centers, which was the first demonstration of electronic conduction in oxides composed only of light elements. Chemical active species such as O- and H- are produced in C12A7 at high densities. In this paper, we first review the structure and properties of C12A7-drived materials and related ab-initio works, and then provide simplified views for the stability of the crystal lattice and the clathrated anions, electronic structure, and carrier transport mechanism using simple models based on crystal chemistry, classical molecular dynamics simulation and effective-mass approximation.

http://iopscience.iop.org/article/10.1143/JJAP.44.774/pdf

Built-in Quantum Dots in Nano-Porous Crystal 12CaO·7Al2O3: Simplified Views for Electronic Structure and Carrier Transport

We synthesized nonequilibrium cubic rock-salt (RS)-type (Sn,Pb)Se and investigated their optoelectronic properties with the expectation that the RS-type structure would exhibit better carrier transport properties than the equilibrium GeS-type layered crystal structure in SnSe because the RS-type structure has the three-dimensional network of (PbSe6) octahedra, while the GeS-type structure has the two-dimensional network of (SnSe3), leading to larger band dispersions and smaller carrier effective masses. To stabilize the nonequilibrium phase, epitaxial thin films were grown by a unique method, a reactive solid-phase epitaxy with a thin RS-type PbSe epitaxial template layer. Additionally, a rapid quenching process from 600 °C to room temperature was also effective for stabilizing the nonequilibrium RS-type (Sn,Pb)Se epitaxial films. We succeeded in controlling Pb concentration continuously from 0 to 100% in the (Sn,Pb)Se solid-solution films. The minimum Pb concentration to stabilize the RS-type SnSe was ex...

Nonequilibrium Rock-Salt-Type Pb-Doped SnSe with High Carrier Mobilities ≈ 300 cm2/(Vs)

The structure of polycrystalline silicon films was controlled by selecting deposition conditions, especially gas mixing ratio of H2/SiF4, for plasma enhanced chemical vapor deposition on glass at a low temperature of 360°C. Under the H2/SiF4 ratio of 10/90 sccms, (111), (220), (311) and (400) diffraction peaks were observed by X-ray diffraction for a 0.5 µm thick film and (400) oriented crystallites grew with film thickness. The sharpness of the Raman peak around 520 cm-1 and the pseudo-dielectric function measured by an ellipsometer indicated that the crystallites have excellent regularity of the Si–Si bond compared with (220) oriented films and also have small surface roughness, which are preferable features for device applications. The selective growth of (400) oriented grains is thought to partly originate from selective etching due to fluorine related species generated under low hydrogen conditions.

Control of Orientation for Polycrystalline Silicon Thin Films Fabricated from Fluorinated Source Gas by Microwave Plasma Enhanced Chemical Vapor Deposition

Toshio Kamiya

Papers

Built-in Quantum Dots in Nano-Porous Crystal 12CaO·7Al2O3: Simplified Views for Electronic Structure and Carrier Transport

Nonequilibrium Rock-Salt-Type Pb-Doped SnSe with High Carrier Mobilities ≈ 300 cm2/(Vs)

Control of Orientation for Polycrystalline Silicon Thin Films Fabricated from Fluorinated Source Gas by Microwave Plasma Enhanced Chemical Vapor Deposition

Multiple Color Inorganic Thin-Film Phosphor, RE-Doped Amorphous Gallium Oxide (RE = Rare Earth: Pr, Sm, Tb, and Dy), Deposited at Room Temperature

Effects of Base Pressure on Growth and Optoelectronic Properties of Amorphous In-Ga-Zn-O: Ultralow Optimum Oxygen Supply and Bandgap Widening