Showing papers on "Amorphous solid published in 2007"

Electrochromics for smart windows: thin films of tungsten oxide and nickel oxide, and devices based on these

Abstract: Electrochromic (EC) materials are able to change their optical properties, reversibly and persistently, by the application of an electrical voltage. These materials can be integrated in multilayer devices capable of modulating the optical transmittance between widely separated extrema. We first review the recent literature on inorganic EC materials and point out that today's research is focused on tungsten oxide (colouring under charge insertion) and nickel oxide (colouring under charge extraction). The properties of thin films of these materials are then discussed in detail with foci on recent results from two comprehensive investigations in the authors' laboratory. A logical exposition is obtained by covering, in sequence, structural features, thin film deposition (by sputtering), electronic band structure, and ion diffusion. A novel conceptual model is given for structural characteristics of amorphous W oxide films, based on notions of defects in the ideal amorphous state. It is also shown that the conduction band density of states is obtainable from simple electrochemical chronopotentiometry. Ion intercalation causes the charge-compensating electrons to enter localized states, implying that the optical absorption underlying the electrochromism can be described as ensuing from transitions between occupied and empty localized conduction band states. A fully quantitative theory of such transitions is not available, but the optical absorption can be modeled more phenomenologically as due to a superposition of transitions between different charge states of the W ions (6+, 5+, and 4+). The Ni oxide films were found to have a porous structure comprised of small grains. The data are consistent with EC coloration being a surface phenomenon, most likely confined to the outer parts of the grains. Initial electrochemical cycling was found to transform hydrated Ni oxide into hydroxide and oxy-hydroxide phases on the grain surfaces. Electrochromism in thus stabilized films is consistent with reversible changes between Ni hydroxide and oxy-hydroxide, in accordance with the Bode reaction scheme. An extension of this model is put forward to account for changes of NiO to Ni2O3. It was demonstrated that electrochromism is associated solely with proton transfer. Data on chemical diffusion coefficients are interpreted for polycrystalline W oxide and Ni oxide in terms of the lattice gas model with interaction. The later part of this review is of a more technological and applications oriented character and is based on the fact that EC devices with large optical modulation can be accomplished essentially by connecting W-oxide-based and Ni-oxide-based films through a layer serving as a pure ion conductor. Specifically, we treat methods to enhance the bleached-state transmittance by mixing the Ni oxide with other oxides characterized by wide band gaps, and we also discuss pre-assembly charge insertion and extraction by facile gas treatments of the films, as well as practical device manufacturing and device testing. Here the emphasis is on novel flexible polyester-foil-based devices. The final part deals with applications with emphasis on architectural “smart” windows capable of achieving improved indoor comfort jointly with significant energy savings due to lowered demands for space cooling. Eyewear applications are touched upon as well.

68.3: Invited Paper: Transparent Amorphous Oxide Semiconductors for High Performance TFT

Abstract: This paper briefly describes unique electron transport properties of transparent amorphous oxide semiconductors (TAOS) for TFT performance along with our material design concept. Emphasized is essential importance of indium ion for emergence of high field effect mobility on the basis of recent results on electronic structure calculation on amorphous InGaZnO4.

An in situ X-ray diffraction study of the reaction of Li with crystalline Si

Abstract: The electrochemical reaction of lithium with a crystalline Si composite electrode at room temperature was investigated using in situ X-ray diffraction (XRD) techniques. The study confirmed that crystalline Si becomes amorphous during the first lithiation. The range of the coexistence region between crystalline Si and amorphous lithiated Si is 3350 ± 200 mAh/g. The highly lithiated amorphous Li x Si phase was found to crystallize into Li 15 Si 4 rapidly at about 60 mV (vs Li/Li + ) and this Li 15 Si 4 phase exists over a relatively narrow range of capacity. During delithiation, the Li 15 Si 4 phase coexists with amorphous Li z Si with z = 2.0 +0 -1 . Once all the Li 15 Si 4 phase disappears, the amorphous phase persists as the remaining Li is extracted. The formation of the Li 15 Si 4 phase can be avoided if the potential of the Si electrode is controlled above 70 mV during cycling. Based on the electrochemical and XRD data, a "phase diagram" was constructed to show the phase changes and regions of phase stability that occur during the lithiation and delithiation of the Si electrode.

Highly-ordered TiO2 nanotube arrays up to 220 µm in length: use in water photoelectrolysis and dye-sensitized solar cells

Abstract: The fabrication of highly-ordered TiO2 nanotube arrays up to 134 µm in length by anodization of Ti foil has recently been reported (Paulose et al 2006 J. Phys. Chem. B 110 16179). This work reports an extension of the fabrication technique to achieve TiO2 nanotube arrays up to 220 µm in length, with a length-to-outer diameter aspect ratio of ≈1400, as well as their initial application in dye-sensitized solar cells and hydrogen production by water photoelectrolysis. The highly-ordered TiO2 nanotube arrays are fabricated by potentiostatic anodization of Ti foil in fluoride ion containing baths in combination with non-aqueous organic polar electrolytes including N-methylformamide, dimethyl sulfoxide, formamide, or ethylene glycol. Depending upon the anodization voltage, the inner pore diameters of the resulting nanotube arrays range from 20 to 150 nm. As confirmed by glancing angle x-ray diffraction and HRTEM studies, the as-prepared nanotubes are amorphous but crystallize with annealing at elevated temperatures.

Organic Glasses with Exceptional Thermodynamic and Kinetic Stability

Abstract: Vapor deposition has been used to create glassy materials with extraordinary thermodynamic and kinetic stability and high density. For glasses prepared from indomethacin or 1,3-bis-(1-naphthyl)-5-(2-naphthyl)benzene, stability is optimized when deposition occurs on substrates at a temperature of 50 K below the conventional glass transition temperature. We attribute the substantial improvement in thermodynamic and kinetic properties to enhanced mobility within a few nanometers of the glass surface during deposition. This technique provides an efficient means of producing glassy materials that are low on the energy landscape and could affect technologies such as amorphous pharmaceuticals.

Black Phosphorus and its Composite for Lithium Rechargeable Batteries

Abstract: Lithium-ion rechargeable batteries are used as portable power sources for a wide variety of electronic devices, such as cellular phones, notebook computers, and camcorders. Intensive research efforts have been made over the past decade to increase the gravimetric and volumetric energy density of lithium ion batteries. At present, graphite (372 mAhg) is used as an anode material for lithium ion batteries, but higher capacity alternatives are being actively pursued. Among the many possible alternatives, a lot of work has been devoted to Sn-based oxide, Si-based composite, transition metal oxide, metal nitride and metal phosphide systems, due to their ability to react reversibly with large amounts of Li per formula unit. Although alloy-based systems have a higher energy density, they suffer from poor capacity retention, since a large volume change occurs during charge/discharge. Among these alternatives, a concept based on the quasi-topotactic intercalation mechanism was proposed, in which lithium is inserted into monoclinic binary MnP4 to form the cubic ternary Li7MnP4 phase. [10] Since then, Li insertion/extraction in transition metal phosphides has been investigated as a possible candidate for the anode material in lithium ion batteries. In these systems, commercial red P and transition metals were used to synthesize metal phosphides, but the energy density is reduced due to the heavy transition metals employed. If phosphorus were used for electrode materials, it would have a good energy density, but little is known about its electrochemical behavior, since commercial red P has an amorphous structure with a poor bulk conductivity and poor cyclability. Phosphorus, an element of the fifth group in the periodic table, has three main allotropes: white, red, and black. Among these modifications of allotropes, black phosphorus is thermodynamically the most stable, insoluble in most solvents, practically non-flammable, and chemically the least reactive form, and exists in three known crystalline modifications (orthorhombic, rhombohedral, and simple cubic), as well as in an amorphous form. Since orthorhombic black phosphorus was obtained from white phosphorus at 200 C and 1.2 GPa, many studies designed to synthesize black phosphorus have been reported. However, the basic concept of a high temperature and high pressure being required has not been changed, and black phosphorus still remains difficult to synthesize, and has the lowest commercial value of the three forms. Considering that orthorhombic black phosphorus exhibits a layer structure similar to that of graphite, which is currently used as an anode material for Li ion batteries, we developed a simple method of transforming commercially available amorphous red phosphorus into orthorhombic black phosphorus using a high energy mechanical milling (HEMM) technique at ambient temperature and pressure. It is known that the temperature during HEMM can rise above 200 C and the pressure generated can be of the order of 6 GPa. These conditions should be sufficient to transform red P into its high-pressure allotrope, the black phosphorus phase, at ambient temperature and pressure. Figure 1a shows the color photo image, XRD pattern, and TEM electron diffraction pattern showing a diffuse ring of red P, which confirms the amorphous nature of the red P. The sample prepared by HEMM corresponds to orthorhombic black P according to the XRD data and color photo image (Fig. 1b), and was also identified by high resolution TEM electron diffraction, and by its lattice spacing. Figure 2a and 2b show the voltage profiles of red P and black P, respectively. Their electrochemical behaviors are very different from each other. The discharge and charge capacities of red P are 1692 and 67 mAhg, respectively, and it cannot be used as an anode material since its charge capacity is negligible. Although black P shows an increased charge capacity of 1279 mAhg, the first cycle efficiency is only 57%. The electrochemical performance of Si as an anode material for Li ion batteries can be much improved using Si–carbon composites. Black P also has a low electronic conductivity inherited from its characteristic as a semiconductor. The electrochemical behaviors of the black P-carbon composite during the discharge/charge reaction with Li were excellent compared with the above two cases, as shown in Figure 2c. The first discharge and charge capacities are 2010 and 1814 mAhg, respectively, and the first cycle efficiency is about 90%, which is one of the highest reported. The good coulombic efficiency of the black P–carbon composite for the C O M M U N IC A IO N

Analytical model for subthreshold conduction and threshold switching in chalcogenide-based memory devices

Abstract: Chalcogenide materials are receiving increasing interest for their many applications as active materials in emerging memories, such as phase-change memories, programmable metallization cells, and cross-point devices. The great advantage of these materials is the capability to appear in two different phases, the amorphous and the crystalline phases, with rather different electrical properties. The aim of this work is to provide a physically based model for conduction in the amorphous chalcogenide material, able to predict the current-voltage (I−V) characteristics as a function of phase state, temperature, and cell geometry. First, the trap-limited transport at relatively low currents (subthreshold regime) is studied, leading to a comprehensive model for subthreshold conduction accounting for (a) the shape of the I−V characteristics, (b) the measured temperature dependence, (c) the dependence of subthreshold slope on the thickness of the amorphous phase, and (d) the voltage dependence of the activation ener...

Vertically oriented Ti-Fe-O nanotube array films: toward a useful material architecture for solar spectrum water photoelectrolysis.

Abstract: In an effort to obtain a material architecture suitable for high-efficiency visible spectrum water photoelectrolysis, herein we report on the fabrication and visible spectrum (380-650 nm) photoelectrochemical properties of self-aligned, vertically oriented Ti-Fe-O nanotube array films. Ti-Fe metal films of variable composition, iron content ranging from 69% to 3.5%, co-sputtered onto FTO-coated glass are anodized in an ethylene glycol + NH4F electrolyte. The resulting amorphous samples are annealed in oxygen at 500 degrees C, resulting in nanotubes composed of a mixed Ti-Fe-O oxide. Some of the iron goes into the titanium lattice substituting titanium ions, and the rest either forms alpha-Fe2O3 crystallites or remains in the amorphous state. Depending upon the Fe content, the band gap of the resulting films ranges from about 380 to 570 nm. The Ti-Fe oxide nanotube array films are utilized in solar spectrum water photoelectrolysis, demonstrating 2 mA/cm2 under AM 1.5 illumination with a sustained, time-energy normalized hydrogen evolution rate by water splitting of 7.1 mL/W.hr in a 1 M KOH solution with a platinum counter electrode under an applied bias of 0.7 V. The surface morphology, structure, elemental analysis, optical, and photoelectrochemical properties of the Ti-Fe oxide nanotube array films are considered.

Polyamorphism in a metallic glass

Abstract: A metal, or an alloy, can often exist in more than one crystal structure. The face-centred-cubic and body-centred-cubic forms of iron (or steel) are a familiar example of such polymorphism. When metallic materials are made in the amorphous form, is a parallel ‘polyamorphism’ possible? So far, polyamorphic phase transitions1,2,3,4,5,6,7 in the glassy state have been observed only in glasses involving directional and open (such as tetrahedral4,5) coordination environments. Here, we report an in situX-ray diffraction observation of a pressure-induced transition between two distinct amorphous polymorphs in a Ce55Al45 metallic glass. The large density difference observed between the two polyamorphs is attributed to their different electronic and atomic structures, in particular the bond shortening revealed by ab initio modelling of the effects of f-electron delocalization8,9,10. This discovery offers a new perspective of the amorphous state of metals, and has implications for understanding the structure, evolution and properties of metallic glasses and related liquids. Our work also opens a new avenue towards technologically useful amorphous alloys that are compositionally identical but with different thermodynamic, functional and rheological properties11 due to different bonding and structural characteristics.

Amorphous gallium indium zinc oxide thin film transistors: Sensitive to oxygen molecules

Abstract: In this study, the authors report characteristic of indium gallium zinc oxides (GIZOs) which is strongly associated with the film surface. In ambient air, turn-on voltage of GIZO thin film transistors is approximately −7V. However, at the pressure of 8×10−6Torr, the turn-on voltage dramatically shifts to nearly −47V of the negative gate bias direction. When the oxygen is introduced in the chamber, the turn-on voltage returns to the normal value, that of air. It is believed that the adsorbed oxygen forms depletion layer below the surface, resulting in Von shifts. The carrier concentration of the channel varies from 1×1019to1×1020cm−3 due to oxygen adsorption.

Coexistence of tetrahedral and octahedral-like sites in amorphous phase change materials

Abstract: Chalcogenide alloys are materials of interest for optical recording and non-volatile memories. We perform ab-initio molecular dynamics simulations aiming at shading light onto the structure of amorphous Ge2Sb2Te5 (GST), the prototypical material in this class. First principles simulations show that amorphous GST obtained by quenching from the liquid phase displays two types of short range order. One third of Ge atoms are in a tetrahedral environment while the remaining Ge, Sb and Te atoms display a defective octahedral environment, reminiscent of cubic crystalline GST.

Toughness of hard nanostructured ceramic thin films

Abstract: This article reports on the investigation of cracking of hard, 3–5 μm thick Zr–Cu–O, Zr–Cu–C, Ti–Cu–C and Si–Me–N (Me = Ta, Zr, Mo, W) magnetron sputtered nanostructured films using microindentation measurements. Main aim of this investigation is to determine the interrelationships between the cracking of film, its structure and mechanical properties and to assess the toughness of thin film. Correlations between the formation of cracks, the mechanical properties of film and substrate, structure of film and macrostress σ generated in the film during its growth were investigated in detail. It was found that the resistance of the film to cracking increases with increasing ratio Hf3/Ef⁎2. It was found that (1) the correct assessment of toughness of the thin film requires to investigate the system thin film/substrate as one unit because mechanical properties of the substrate play a decisive role in the formation of cracks, (2) the strongest parameter influencing the formation of cracks is the film structure and its macrostress σ and (3) nanostructured films with X-ray amorphous structure and small compressive macrostress (σ ≈ − 0.1 GPa) are very stable against the cracking even at high values of the film hardness Hf exceeding 20 GPa.

Catalytic efficiency of iron(III) oxides in decomposition of hydrogen peroxide: competition between the surface area and crystallinity of nanoparticles.

Abstract: Various iron(III) oxide catalysts were prepared by controlled decomposition of a narrow layer (ca. 1 mm) of iron(II) oxalate dihydrate, FeC2O4·2H2O, in air at the minimum conversion temperature of 175 °C. This thermally induced solid-state process allows for simple synthesis of amorphous Fe2O3 nanoparticles and their controlled one-step crystallization to hematite (α-Fe2O3). Thus, nanopowders differing in surface area and particle crystallinity can be produced depending on the reaction time. The phase composition of iron(III) oxides was monitored by XRD and 57Fe Mossbauer spectroscopy including in-field measurements, providing information on the relative contents of amorphous and crystalline phases. The gradual changes in particle size and surface area accompanying crystallization were evaluated by HRTEM and BET analysis, respectively. The catalytic efficiency of the synthesized nanoparticles was tested by tracking the decomposition of hydrogen peroxide. The obtained kinetic data gave an unconventional no...

Coexistence of tetrahedral- and octahedral-like sites in amorphous phase change materials

Abstract: Chalcogenide alloys are materials of interest for optical recording and nonvolatile memories. We perform ab initio molecular dynamics simulations aiming at shading light onto the structure of amorphous Ge2Sb2Te5 (GST), the prototypical material in this class. First principles simulations show that amorphous GST obtained by quenching from the liquid phase displays two types of short range order. One third of Ge atoms are in a tetrahedral environment while the remaining Ge, Sb, and Te atoms display a defective octahedral environment, reminiscent of cubic crystalline GST.

Effect of Molecular Weight on the Structure and Morphology of Oriented Thin Films of Regioregular Poly(3-hexylthiophene) Grown by Directional Epitaxial Solidification†

Abstract: Regioregular head-to-tail (HT)-coupled poly(3-hexylthiophene-2,5-diyl) (P3HT) with a weight-average molecular weight (Mw) in the 7.3–69.6 kDa range is crystallized by directional epitaxial solidification in 1,3,5-trichlorobenzene (TCB) to yield highly oriented thin films. An oriented and periodic lamellar structure consisting of crystalline lamellae separated by amorphous interlamellar zones is evidenced by atomic force microscopy (AFM) and transmission electron microscopy (TEM). Both the overall crystallinity as well as the orientation of the crystalline lamellae decrease significantly with increasing Mw. The total lamellar periodicity is close to the length of “fully extended” chains for Mw = 7.3 kDa (polystyrene-equivalent molecular weight, eq. PS) and it saturates to a value of ca. (25–28) ± 2 nm for Mw ≥ 18.8 kDa (eq. PS). This behavior is attributed to a transition from an oligomeric-like system, for which P3HT chains are essentially in a fully extended all-trans conformation and do not fold, to a semicrystalline system that involves a periodic alternation of crystalline lamellae separated by extended amorphous interlamellar zones, which harbor chain folds, chain ends, and tie molecules. For P3HT with Mw of ca. 7.3 kDa (eq. PS), epitaxial crystallization on TCB allows for the growth of both “edge-on” and “flat-on” oriented crystalline lamellae on the TCB substrate. The orientation of the lamellae is attributed to 1D epitaxy. Because of the large size of the “flat-on” crystalline lamellae, a characteristic single-crystal electron diffraction pattern corresponding to the [001] zone was obtained by selected area electron diffraction (SAED), indicating that P3HT crystallizes in a monoclinic unit cell with a = 16.0 A, b = 7.8 A, c = 7.8 A, and γ = 93.5°.

Interaction potential for silicon carbide: A molecular dynamics study of elastic constants and vibrational density of states for crystalline and amorphous silicon carbide

Abstract: An effective interatomic interaction potential for SiC is proposed. The potential consists of two-body and three-body covalent interactions. The two-body potential includes steric repulsions due to atomic sizes, Coulomb interactions resulting from charge transfer between atoms, charge-induced dipole-interactions due to the electronic polarizability of ions, and induced dipole-dipole (van der Waals) interactions. The covalent characters of the Si–C–Si and C–Si–C bonds are described by the three-body potential. The proposed three-body interaction potential is a modification of the Stillinger-Weber form proposed to describe Si. Using the molecular dynamics method, the interaction potential is used to study structural, elastic, and dynamical properties of crystalline (3C), amorphous, and liquid states of SiC for several densities and temperatures. The structural energy for cubic (3C) structure has the lowest energy, followed by the wurtzite (2H) and rock-salt (RS) structures. The pressure for the structural transformation from 3C-to-RS from the common tangent is found to be 90 GPa. For 3C-SiC, our computed elastic constants (C11, C12, and C44), melting temperature, vibrational density-of-states, and specific heat agree well with the experiments. Predictions are made for the elastic constant as a function of density for the crystalline and amorphous phase. Structural correlations, such as pair distribution function and neutron and x-ray static structure factors are calculated for the amorphous and liquid state.

Amorphous iron(III) oxide--a review.

Abstract: The syntheses of amorphous Fe(2)O(3) nanoparticles of varying size and morphology, their magnetic properties, crystallization mechanism, and applications are reviewed herein. The synthetic routes are classified according to the nature of the sample (powders, nanocomposites, films, coated particles). The contributions of various experimental techniques to the characterization of an amorphous Fe(2)O(3) phase are considered in this review, including some key experimental markers, allowing its distinction from nanocrystalline "X-ray amorphous" polymorphs (maghemite, hematite). We discuss the thermally induced crystallization mechanisms depending on transformation temperature, atmosphere, and the size of the amorphous particles that predetermine the structure of the primarily formed crystalline polymorph. The controversial description of the magnetic behavior, including an interpretation of the low-temperature and in-field Mossbauer spectra, is analyzed.

Semiconductor and ceramic nanoparticle films deposited by chemical bath deposition

Abstract: Chemical bath deposition (CBD) has been used to deposit films of metal sulfides, selenides and oxides, together with some miscellaneous compounds, beginning nearly 140 years ago. While it is a well-known technique in a few specific areas (notably photoconductive lead salt detectors, photoelectrodes and more recently, thin film solar cells), it is by and large an under-appreciated technique. The more recent interest in all things ‘nano’ has provided a boost for CBD: since it is a low temperature, solution (almost always aqueous) technique, crystal size is often very small. This is evidenced by the existence of size quantization commonly found in CBD semiconductor films. The intention of this review is to provide readers, many of whom may not even be aware of the CBD technique, with an overview of how the technique has been used to fabricate nanocrystalline semiconductor (this terminology also includes oxides often classified as ceramics) films and some properties of these films. The review begins, after a short introduction, with a general description of the CBD method, designed to give the reader a basic knowledge of the technique. The rest of the review then focuses on nanocrystalline (or, in the few cases of amorphous deposits, nanoparticle) films. The various factors which determine crystal size are first discussed. This is followed by some of the many examples of size quantization observed in the films. Since CBD films are usually porous, surface effects can be very important, and various surface-dependent properties (light emission and surface states) as well as surface modification, are treated: (although some properties, like emission, can be strongly dependent on both surface and ‘bulk’). Because of the fact that many CBD films have been made specifically for use as photoelectrodes in photoelectrochemical cells, there is next a chapter on this topic with a few examples of such photoelectrodes. Film structure and morphology follows with examples of patterning, porosity and crystal shape. The review concludes with some of the author’s opinions as to what the near future holds for CBD development in general.

Selective epitaxial formation of semiconductor films

Abstract: Epitaxial layers (125) are selectively formed in semiconductor windows (114) by a cyclical process of repeated blanket deposition and selective etching. The blanket deposition phases leave non-epitaxial material (120) over insulating regions (112), such as field oxide, and the selective etch phases preferentially remove non-epitaxial material (120) while deposited epitaxial material (125) builds up cycle-by-cycle. Quality of the epitaxial material (125) improves relative to selective processes where no deposition occurs on insulators (112). Use of a germanium catalyst during the etch phases of the process aids etch rates and facilitates economical maintenance of isothermal and/or isobaric conditions throughout the cycles. Throughput and quality are improved by use of trisilane, formation of amorphous material (120) over the insulating regions (112) and minimizing the thickness ratio of amorphous:epitaxial material in each deposition phase.

Combinatorial approach to thin-film transistors using multicomponent semiconductor channels: An application to amorphous oxide semiconductors in In–Ga–Zn–O system

Abstract: A combinatorial approach was applied to thin-film transistors (TFTs) using amorphous In–Ga–Zn–O semiconductor channels. A large number of TFTs, having n-type channels with different chemical compositions, were fabricated simultaneously on a substrate. A systematic relation was clarified among the compositional ratio of In:Ga:Zn, oxygen partial pressure in film deposition atmosphere, and TFT characteristics. The results provide an experimental basis to understand the roles of each metallic element in the In–Ga–Zn–O system. This information leads to a guideline to tune the metallic compositions for required TFT specifications.

Structural studies of disordered materials using high-energy x-ray diffraction from ambient to extreme conditions

Abstract: High-energy x-rays from a synchrotron radiation source allow us to obtain high-quality diffraction data for disordered materials from ambient to extreme conditions, which is necessary for revealing the detailed structures of glass, liquid and amorphous materials. We introduced high-energy x-ray diffraction beamlines and a dedicated diffractometer for glass, liquid and amorphous materials at SPring-8 and report the recent developments of ancillary equipment. Furthermore, the structures of liquid and amorphous materials determined from the high-energy x-ray diffraction data obtained at SPring-8 are discussed.

Hydrogen-doped In2O3 as High-mobility Transparent Conductive Oxide

Abstract: We have developed hydrogen (H)-doped In2O3 films on glass with high mobility and high near-infrared transparency by using sputtering process performed at room temperature, followed by post-annealing treatment at 200 °C. To incorporate H-donor into In2O3 matrix, H2O vapor has been introduced into a chamber during the deposition. In the post-annealing of the films, phase transition from amorphous to polycrytalline was confirmed to occur. The resulting In2O3 films containing 1.9–6.3 at. % H show quite large mobility as high as 98–130 cm2/(V s) at carrier density of (1.4–1.8)×1020 cm-3. We attributed the high mobility in the film to suppression of grain boundary defects as well as multicharged and neutral impurities.