In2O3-ZnO transparent conductive oxide film deposition on polycarbonate substrates

Amorphous transparent conductive oxide films in the In-Zn-O system were deposited on polycarbonate (PC) substrates by simultaneous DC sputtering of an In₂O₃ target and a ZnO target with either 4 wt% Al₂O₃ or 7.5 wt% Ga₂O₃ impurities. Although the resistivity of the amorphous, non-doped In-Zn-O film on PC was about one order of magnitude higher than that on the glass substrate, the resistivity of the In-Zn-O films with Ga₂O₃ impurities on PC substrates was reduced to the level of the non-doped In-Zn-O films on glass substrates. The addition of Al₂O₃ or Ga₂O₃ to the In-Zn-O films also induced the widening of the optical band gap, which would improve transparency at blue wavelengths.     

Synthesis of GaN nanorods by ammoniating Ga2O3 films on In2O3 layer deposited on Si (111) substrates

GaN nanorods were synthesized by ammoniating Ga₂O₃/In₂O₃ thin films deposited on Si (111) with magnetron sputtering. X-ray diffraction, Scanning electronic microscope and high-resolution TEM results show that they are GaN single crystals, the sizes of which vary from 2 to 7 μm in length and 200 to 300 nm in diameter. In₂O₃ middle layer plays an important role in the GaN nanorod growth.     

Gas sensor based on ordered mesoporous In2O3

We present the preparation of a semiconductor gas sensor based on ordered mesoporous In₂O₃. The In₂O₃ was synthesized by structure replication procedure from cubic KIT-6 silica. A detailed analysis of the morphology of the mesoporous powders as well as of the prepared sensing layer will be shown. Unique properties arise from the synthesis method of structure replication such as well defined porosity in the mesoporous regime and nanocrystallites with high thermal stability up to 450 °C. These properties are useful for the application in semiconducting gas sensors. Test measurements show sensitivity to methane gas in concentrations relevant for explosion prevention.     

Optical properties of In2O3 films prepared by spray pyrolysis

In₂O₃ thin films have been deposited on glass substrates by spray pyrolysis. InCl₄ was used as the solute to prepare the starting solution with a concentration of 0.1 M. The films were grown at different substrate temperatures ranging from 300 to 400 °C. The as-grown layers were optically characterized in order to evaluate the absorption coefficient, optical band gap, refractive index, extinction coefficient and other optical parameters. The influence of substrate temperature on these parameters was reported and discussed.     

Structural instability of Sn-doped In2O3 thin films during thermal annealing at low temperature

We report on observations of structural stability of Sn-doped In₂O₃ (ITO) thin films during thermal annealing at low temperature. The ITO thin films were deposited by radio-frequency magnetron sputtering at room temperature. Transmission electron microscopy analysis revealed that the as-deposited ITO thin films are nanocrystalline. After thermal annealing in a He atmosphere at 250 °C for 30 min, recrystallization, coalescence, and agglomeration of grains were observed. We further found that nanovoids formed in the annealed ITO thin films. The majority of the nanovoids are distributed along the locations of the original grain boundaries. These nanovoids divide the agglomerated larger grains into small coherent domains.     

Room temperature ferromagnetism in Ni doped In2O3 nanoparticles

In the present work, Ni doped In₂O₃ nanoparticles were prepared using simple co-precipitation method. From the x-ray diffraction analysis it is observed that all samples exhibit single phase polycrystalline nature. All the diffraction lines correspond to the bixbyite type cubic structure. A UV visible analysis reveals that optical band gap decreases from 4.63 to 3.84 eV with Ni doping. DC magnetization measurements reveal that Ni doped In₂O₃ nanoparticles exhibit room temperature ferromagnetism.     

Varistor properties of ZnO-Pr6O11-CoO-Cr2O3-Y2O3-In2O3 ceramics

The varistor properties of the ZnO-Pr₆O₁₁-CoO-Cr₂O₃-Y₂O₃-In₂O₃ ceramics were investigated for different concentrations of In₂O₃. The increase of In₂O₃ concentration slightly increased the sintered density (5.60-5.63 g/cm³) and slightly decreased the average grain size (3.4-2.9 μm). The breakdown field increased from 6023 to 14822 V/cm with increasing concentration of In₂O₃. The nonlinear coefficient increased from 17.6 to 44.6 for up to 0.005 mol%, whereas the further doping caused it to decrease to 36.8. In₂O₃ acted as an acceptor due to the donor concentration, which decreases in the range of 1.02 × 10¹⁷ to 0.24 × 10¹⁷/cm³ with increasing concentration of In₂O₃.     

Material properties and growth control of undoped and Sn-doped In2O3 thin films prepared by using ion beam technologies

Undoped (IO) and Sn-doped In₂O₃ (ITO) films have been deposited on glass and polymer substrates by an advanced ion beam technologies including ion-assisted deposition (IAD), hybrid ion beam, ion beam sputter deposition (IBSD), and ion-assisted reaction (IAR). Physical and chemical properties of the oxide films and adhesion between films and substrates were improved significantly by these technologies. By using the IAD method, non-stoichiometry and microstructure of the films were controlled by changing assisted oxygen ion energy and arrival ratio of assisted oxygen ion to evaporated atoms. Relationships between structural and electrical properties in ITO films on glass substrates were intensively investigated by using the IBSD method with changing ion energy, reactive gas environment, and substrate temperature. Smooth-surface ITO films (R_rms ≤ 1 nm and R_p-v ≤ 10 nm) for organic light-emitting diodes were developed with a combination of deposition conditions with controlling microstructure of a seed layer on glass. IAR surface treatment enormously enhanced the adhesion of oxide films to polymer substrate. The different dependence of IO and ITO films' properties on the experimental parameters, such as ion energy and oxygen gas environment, will be intensively discussed.     

Solvothermal synthesis of In(OH)3 nanorods and their conversion to In2O3

In this work, we demonstrate that monodisperse indium hydroxide (In(OH)₃) nanorods constructed with parallel wire-like subunits have been fabricated via a acrylamide-assisted synthesis route without any template. NH₃ from the hydrolysis of acrylamide acts as the OH⁻ provider. The structure and morphology of as-prepared products have been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and thermogravimetric analysis (TG). A detailed mechanism has been proposed on the basis of time-dependent experimental results. Furthermore, by annealing In(OH)₃ precursors at 500 °C for 3 h in air, In₂O₃ samples were obtained with the designed morphology.     

In2O3 nanowires for gas sensors: morphology and sensing characterisation

Thin and densely packed In₂O₃ nanowires have been synthesised on alumina substrates via transport and condensation method, starting from nanoparticles of indium or palladium as catalysts for the condensation process. Indium catalyst promoted wires growth according to vapour-solid (VS) mechanism, while palladium catalyst leads to wires formation based on vapour-liquid-solid (VLS) condensation. Electron microscopy and related diffraction analysis demonstrated that the wires are monocrystalline, with atomically sharp termination of the lateral sides, and are free from extended defects. The sensing properties of nanowires bundles have been tested to acetone using the flow through technique in the temperature range between 100 and 500 °C.     

Structural study of amorphous In2O3 film by grazing incidence X-ray scattering (GIXS) with synchrotron radiation

Grazing incidence X-ray scattering (GIXS) using synchrotron radiation is a very useful method for structural analysis of amorphous films. We investigated the structure of amorphous In₂O₃ film utilizing GIXS at BL19B2 in SPring-8. Radial distribution function (RDF) was obtained from the measurement data. Structural models were constructed by molecular dynamics (MD) and reverse Monte-Carlo (RMC) simulations, and the calculated RDFs from the simulations were compared with that observed. It was found that the average oxygen coordination number around In ions was almost 6 and the average length 2.12 Å, which was smaller by about 3% than that of 2.18 Å in crystalline In₂O₃. It was concluded that the atomic arrangement of the amorphous In₂O₃ was characterized by the increase in the number and the boarder angle of distribution of corner-sharing In-O-In bond compared with crystalline In₂O₃.     

Controlled synthesis and photocatalytic properties of porous hollow In2O3 microcubes with different sizes

Uniform single-crystalline In(OH)₃ hollow microcubes have been synthesized in large quantities via a hydrothermal reaction of InCl₃ with NaF and ethylene glycol (EG) at 140–220 °C for 12 h. Porous In₂O₃ hollow microcubes with a polycrystalline cubic structure can be obtained via calcining In(OH)₃ precursors at 400 °C for 2 h in air. Controlled Synthesis of In(OH)₃ and In₂O₃ hollow microcubes with the average edge lengths in the range of 2.0–4.7 μm can be achieved by changing the hydrothermal reaction temperature. The In(OH)₃ hollow microcubes were formed via an EG-assisted oriented attachment growth route using HF bubbles as the templates. Photocatalytic activities of the as-synthesized porous In₂O₃ hollow microcubes were studied at room temperature. The results indicated that the hollow In₂O₃ nanostructures display high photocatalytic activity in the photodegradation of rhodamine B and methyl orange.     

Y2O3添加量对Al2O3/ZrO2共晶陶瓷显微组织及力学性能的影响

为探索第三组元Y₂O₃添加对Al₂O₃/ZrO₂共晶陶瓷显微组织与机械性能的影响,本文利用低温度梯度的高温熔凝法制备了直径为20 mm的Al₂O₃/ZrO₂(Y₂O₃)共晶陶瓷块体,采用SEM、EDS及XRD技术对共晶陶瓷进行微结构分析,并利用维氏压痕法对其硬度和断裂韧性进行测试。SEM结果表明,凝固组织由群集的共晶团结构组成,随着Y₂O₃添加量的增加,共晶团形态由胞状转变为枝晶状,内部相间距在1~2 μm范围内变化。力学测试表明,Y₂O₃摩尔分数小于1.1%时,由于组织内部存在低硬度m-ZrO₂及微裂纹缺陷,故陶瓷硬度较低,约为(9.53±0.22 )GPa;当Y₂O₃摩尔分数为1.1%时,陶瓷硬度最大,约为(18.05±0.27)GPa;当Y₂O₃的摩尔分数大于1.1%时,由于共晶团边界区内气孔缺陷及粗大组织增多,引起陶瓷硬度值略有下降。低Y₂O₃摩尔分数添加时,陶瓷断裂韧性相对较高,约为(6.30±0.16)MPa·m^1/2,这与其内部存在大量微裂纹缺陷有关;随着Y₂O₃添加量的增加,陶瓷的微裂纹数量减少、边界区内缺陷增多,断裂韧性降低。     

High-rate deposition of high-quality Sn-doped In2O3 films by reactive magnetron sputtering using alloy targets

Sn-doped In₂O₃ (ITO) films were deposited on heated (200 °C) fused silica glass substrates by reactive DC sputtering with mid-frequency pulsing (50 kHz) and a plasma control unit combined with a feedback system of the optical emission intensity for the atomic O* line at 777 nm. A planar In-Sn alloy target was connected to the switching unit, which was operated in the unipolar pulse mode. The power density on the target was maintained at 4.4 W cm^− 2 during deposition. The feedback system precisely controlled the oxidation of the target surface in “the transition region.” The ITO film with lowest resistivity (3.1 × 10^− 4 Ω cm) was obtained with a deposition rate of 310 nm min^− 1 and transmittance in the visible region of approximately 80%. The deposition rate was about 6 times higher than that of ITO films deposited by conventional sputtering using an oxide target.     

XPS and AFM studies of surface chemistry and morphology of In2O3 ultrathin films deposited by rheotaxial growth and vacuum oxidation

In this paper, the results of XPS and AFM studies of the surface chemistry and morphology of In₂O₃ nanolayers obtained by rheotaxial growth and vacuum oxidation (RGVO) technology are presented. The ultrathin In films were deposited under UHV by thermal evaporation of indium pellets on the well defined Si substrate maintained at different temperatures. Optimal conditions to obtain the smallest grains and highest surface coverage have been determined, which was controlled by AFM, whereas the cleanness of deposited In nanolayers was controlled by XPS method. The ultrathin films of In₂O₃ (nm scale) were obtained in two ways, i.e. by oxidation of ultrathin films of In after their deposition, as well as by oxidation of In ultrathin films already during the deposition process. The XPS experiments showed that in both cases the obtained ultrathin films of In₂O₃ were almost stoichiometric. In turn, the AFM studies confirmed that only ultrathin films obtained during the simultaneous In deposition and oxidation exhibit almost flat surface morphology with average roughness at the level of about 0.85 nm.     

Structural,optical and electrical properties of In4Sn3O12 films prepared by pulsed laser deposition

Highly conducting (σ ∼ 2.6 × 10³ Ω⁻¹ cm⁻¹) In₄Sn₃O₁₂ films have been deposited using pulsed laser deposition (PLD) on glass and quartz substrates held at temperatures between 350 and 550 °C under chamber pressures of between 2.5 and 15 mTorr O₂. The crystallinity and the surface roughness of the films were found to increase with increasing substrate temperature. Electron concentrations of the order of 5 × 10²⁰ cm⁻³ and mobilities as high as 30 cm² V⁻¹ s⁻¹ were determined from Hall effect measurements performed on the films. Fitting of the transmission spectral profiles in the ultra-violet–visible spectrum has allowed the determination of the refractive index and extinction coefficient for the films. A red-shift in the frequency of plasmon resonance is observed with both increasing substrate temperature and oxygen pressure. Effective masses have been derived from the plasma frequencies and have been found to increase with carrier concentration indicating a non-parabolic conduction band in the material In₄Sn₃O₁₂. The optical band-gap has been determined as 3.8 eV from the analysis of the absorption edge in the UV. These results highlight the potential of these films as lower In-content functional transparent conducting materials.     

Thermo-optic properties of TiO2, Ta2O5 and Al2O3 thin films for integrated optics on silicon

The direct measurement of the thermo-optic coefficients of aluminium oxide, tantalum pentoxide and titanium dioxide thin films is presented. Using ellipsometry on monolithically integrated permutations of the layers of silicon, silicon dioxide and the material under test, allows the direct measurement of the overall thermo-optic coefficient accounting for thermally induced changes in the dielectric permittivity and density of the materials as well as the elasto-optic effect due to the non-matching thermal expansion coefficients of the different materials.     

Photoluminescence properties of the In2O3 octahedrons synthesized by carbothermal reduction method

In₂O₃ octahedrons were synthesized by carbothermal reduction method. The products were characterized by X-ray diffraction (XRD), energy dispersive X-ray (EDX), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected-area electron diffraction analysis (SAED) and room-temperature photoluminescence (PL) spectra. The results show that the products are single-crystalline In₂O₃ octahedrons with the arrises length in the range of 400-3000 nm. The PL spectra displays blue and green emission peaks which can be indexed to default and oxygen vacancies; blue-shift and intensity decrease was observed when excitation wavelength decreases from 380 nm to 325 nm. The growth mechanism of the In₂O₃ octahedrons is discussed.     

Ga2O3 nanowires grown on GaN-Ga2O3 core-shell nanoparticles using a new method: Structure, morphology, and composition

Ga₂O₃ nanowires grown on GaN-Ga₂O₃ core-shell nanoparticles were prepared through heat-treating GaN powder method which comprises a pre-nitridation process in the flow of N₂ gas and a post-oxidation process in the air at 1200 °C. XRD and EDS patterns indicated that the heat-treated GaN powders were a powder mixture of GaN and Ga₂O₃. SEM, TEM, HRTEM and SAED images revealed that some nanowires that grow out from the edge of the GaN-Ga₂O₃ core-shell nanostructures with atomically smooth interfaces were monoclinic Ga₂O₃. Large blue-shifts in vibration frequency of Ga-N bonds observed in the FTIR spectrum could be contributed to size confinement effect and internal strains in GaN nanoparticles.     

Synthesis and photocatalytic activity of cobalt oxide doped ZnFe2O4-Fe2O3-ZnO mixed oxides

Novel cobalt oxide doped ZnFe₂O₄-Fe₂O₃-ZnO mixed oxides with the Zn/Fe molar ratio of 1/2 were synthesized with a citric acid complex method. The effects of cobalt oxide and calcination temperature on phase composition and photocatalytic activity of the mixed oxides were investigated. X-ray diffraction (XRD) analysis revealed that there were mainly ZnFe₂O₄, α-Fe₂O₃, amorphous ZnO and Fe₂O₃ in the 6 mol% cobalt oxide doped products calcined at 500 °C. 5-10 mol% cobalt oxide doping could significantly enhance the formation of ZnFe₂O₄ and altered the phase composition of the mixed oxides. Experimental results showed that cobalt oxide doping could remarkably improve the photocatalytic activity of the mixed oxides for phenol degradation. The 6 mol% cobalt oxide doped mixed oxides calcined at 500 °C exhibited better photocatalytic activity as compared with other samples.