Effect of surfactants on the structure and photoelectric properties of ITO films by sol-gel method

The Indium tin oxide（ITO） thin film possesses excellent photoelectric properties that enable it to act as an ideal transparent conductor.To obtain high-quality ITO films through sol-gel method, the ionic surfactant monoethanolamine and the non-ionic surfactant polyethylene glycol（PEG） were added to the ITO precursor slurry.The influences of surfactants on the structural and photoelectric properties of ITO film samples were investigated.XRD patterns indicated that surfactant monoethanolamine contributed to film predominant grain orientation along the（400） plane.The high transmittance（over 95%） was attributed to the preferred orientation and the grain size expansion of ITO films.SEM showed that the surface particle size and the morphology of ITO films were strongly dependent on the kind of surfactants used.Moving to the shortwave region, the absorption edge of the films exhibited the Burstein-Moss shift.

Influence of Deposition Temperature and Pressure on Microstructure and Tribological Properties of Arc Ion Plated Ag Films

The films deposited at low temperature（LT-films） have increasingly attracted theoretical and technical interests since such films exhibit obvious difference in structure and performances compared to those deposited at room temperature.Studies on the tribological properties of LT-films are rarely reported in available literatures.In this paper,the structure,morphology and tribological properties of Ag films,deposited at LT（166 K） under various Ar pressures on AISI 440C steel substrates by arc ion plating（AIP）,are studied by X-ray diffraction（XRD）,atomic force microscopy（AFM） and a vacuum ball-on-disk tribometer,and compared with the Ag films deposited at RT（300 K）.XRD results show that（200） preferred orientation of the films is promoted at LT and low Ar pressure.The Crystallite sizes are 70 nm-80 nm for LT-Ag films deposited at 0.2 Pa and 0.8 Pa and larger than 100 nm for LT-Ag films deposited at 0.4 Pa and 0.6 Pa,while they are 55 nm-60 nm for RT-Ag films deposited at 0.2 Pa-0.6 Pa and 37 nm for RT-Ag films deposited at 0.8 Pa.The surfaces of LT-Ag films are fibre-like at 0.6 Pa and 0.8 Pa,terrace-like at 0.4 Pa,and sphere-like at 0.2 Pa,while the surfaces of RT-Ag films are composed of sphere-like grains separated by voids.Wear tests reveal that,due to the compact microstructure LT-Ag films have better wear resistances than RT-Ag film.These results indicate that the microstructure and wear resistance of Ag films deposited by AIP can be improved by low temperature deposition.

Light output improvement of GaN-based light-emitting diodes grown on Si (111) by a via-thin-film structure

This work reports the fabrication of via-thin-film light-emitting diode （via-TF-LED） to improve the light output power （LOP） of blue/white GaN-based LEDs grown on Si （111） substrates. The as-fabricated via-TF-LEDs were featured with a roughened n-GaN surface and the p-GaN surface bonded to a wafer carrier with a silver-based reflective electrode, together with an array of embedded n-type via pillar metal contact from the p-GaN surface etched through the multiple-quantum-wells （MQWs） into the n-GaN layer. When operated at 350 mA, the via-TF- LED gave an enhanced blue LOP by 7.8% and over 3.5 times as compared to the vertical thin-film LED （TF-LED） and the conventional lateral structure LED （LS-LED）. After covering with yellow phosphor that converts some blue photons into yellow light, the via-TF-LED emitted an enhanced white luminous flux by 13.5% and over 5 times, as compared with the white TF-LED and the white LS-LED, respectively. The significant LOP improve- ment of the via-TF-LED was attributed to the elimination of light absorption by the Si （111） epitaxial substrate and the finger-like n-electrodes on the roughened emitting surface.

Electromagnetic analysis of GMI effect in sandwich structured films

A model of giant magneto-impedance （GMI） effect in sandwich-structured film has been proposed based on the superposition principle of electromagnetic field. The expression of impedance is derived in the frames of electrodynamics and ferromagnetism. Electromagnetic interaction between the inner layer and outer layer is discussed. Numerical simulation is conducted and the results show that the conductivity of the inner layer is much larger than that of the outer ferromagnetic layer. The skin effect and the maximum GMI effect of the sandwich film may appear at a much lower frequency compared to that of monofilm. The computational results agree with experimental data.

Crystal Structure during Film Formation

For evaporation-deposited Ti films, face-centred cubic structure was observed at the initial stage of film growth, then transited to the hexagonal close-packed structure during film growing (less than 50 nm thick). While. for ion-beam sputter-deposited films. the structure of films always kept the fcc structure during all stages of film formation. The structure of film at initial growth stages relates with the substrate. It is discussed that different film processes and different growth stages provide different thermodynamic condition of film formation and result in the different crystal structures of films during the film formation

Composition and Microstructure of Magnetron Sputtering Deposited Ti-containing Amorphous Carbon Films

Ti-containing carbon films were deposited by using magnetron sputtering deposition. The composition and microstructure of the carbon films were characterized in detail by combining the techniques of Rutherford backscattering spectrometry （RBS）, X-ray photoelectron spectroscopy （XPS）, X-ray diffraction （XRD） and transmission electron microscopy （TEM）. It is found that carbon films contain Ti 18 at pct; after Ti incorporation, the films consist of titanium carbide; C1s peak appears at 283.4 eV and it could be divided into 283.29 and 284.55 eV, representing sp2 and sp3, respectively, and sp2 is superior to sp3. This Ti-containing film with dominating sp2 bonds is nanocomposites with nanocrystalline TiC clusters embedded in an amorphous carbon matrix, which could be proved by XRD and TEM.

THE STRUCTURE OF LANGMUIR-BLODGETT FILMS OF TETRA-NONYL PHTHALOCYANINE COPPER

Langmuir-Blodgett(LB)films of tetra-nonyl phthalocyanine copper (TNPcCu)were prepared.Molecular arrangement and orientation of these films were studied in detail.LB multilayer films of TNPcCu show a very Strong x-ray diffration peak and two weak peaks which indicate that the LB films form a quasi-crystal structure which molecules are arranged orderly.IR reflection absorption spectra and polarized VIS absorption spectra not only confirm the previous result but also indicate that phthalocyanine rings orient nearly perpendicular to the substrate surface and perpendicular to the lifting direction and the side-chain segments are not preferred oriented.

Evolution of Magnetic Domain Structure in a YIG Thin Film

The evolution of a magnetic domain structure induced by temperature and magnetic field is reported in silicon- doped yttrium iron garnet （YIG） films with perpendicular anisotropy. During a cooling-down procedure from 300K to 7K, a 20% change in the domain width is observed, with the long tails of the stripes being shortened and the twisting stripes being straightened. Under the influence of the stray field of a barium ferrite, the garnet presents an interesting domain structure, which shows an appearance of branching protrusions. The intrinsic mechanisms in these two processes are also discussed.

Coacervate Structures of CdI_2 Thin Film Grown during Phase Transformation

The microstructure of CdI2 thin film grown during vapor-phase deposition was investigated by scanning electron microscopy (SEM). The thin film deposited on Si crystal consists of numerous sunflower-like aggregates. These aggregates display well self-assembly characteristics. The size of Sunflower-like aggregates is between 12 and 44 μm. Each sunflower-like aggregate is surrounded with many adjacent wings-'petals'. The structure of central region of the 'sunflower' is obviously difFerent from that of the 'petal'. Electron spectroscopy for chemical analysis (ESCA) was employed in determining the chemical valence of the thin film. Self-organization efFect is used to explain the coring growth process of CdI2 thin film

Morphology and Structure of SiO_2 Film Using Thermal Oxidation Process on(111)Silicon Crystals in Dry Oxygen Atmosphere

By means of scanning electron microscope(SEM)and high voltage electron microscope(HVEM)we have observed and analysed morphology and micro-structure of silicon oxide film with different thickness formed on(111)silicon monocrystal under dry oxygen atmosphere at 1100℃.Compared with their oxidation kinetic curves consisted of three stages,we suggested a mechanism on forming silicon oxide film.According to electron and X-ray diffraction analyses the silicon oxide films consisted of silica with different crystal structure.We also have discussed a stacking fault and a dislocation formed in the Si-Sio_2 interface region simulaneously forming silicon oxide film.

Structure and Magnetic Properties of Fe-N Films Prepared by Dual Ion Beam Sputtering

Fe-N films were prepared on Si substrate by dual ion beam sputtering (DIBS). It is found that the crystal structure of the films varies from α-Fe, to ε-Fe2-3N, ε-Fe2-3N +γ-Fe4N, and finally γ'-Fe4N with the increase in substrate temperature (TS). The magnetic properties of the films were investigated by a vibrating sample magnetometer (VSM). The structure of the films is insensitive to the ratios of N2/Ar in main ion source(MIS), and is mainly influenced by the substrate temperature (Ts).

Structure and Strain Properties of GaN Films Grown on Si（111） Substrates with AlxGa1-xN/AlyGa1-yN Superlattices

CaN films with an AlxGa1-xN/AlyGa1-xN superlattice （SL） buffer layer are grown on Si（111） substrates by metal-organic chemical vapor deposition （MOCVD）. The structure and strain properties of the samples are studied by optical microscopy, Raman spectroscopy, x-ray diffractometry and atomic force microscopy. The results show that the strain status and crystalline quality of the CaN layers are strongly dependent on the difference of the Al composition between AlxCa1-xN barriers and AlyCa1-yN wells in the SLs. With a large Al composition difference, the CaN film tends to generate cracks on the surface due to the severe relaxation of the SLs. Otherwise, when using a small Al composition difference, the crystalline quality of the CaN layer degrades due to the poor function of the SLs in filtering dislocations. Under an optimized condition that the Al composition difference equals 0.1, the crack-free and compressive strained CaN film with an improved crystalline quality is achieved. Therefore, the AlxGa1-xN/AlyGal-yN SL buffer layer is a promising buffer structure for growing thick CaN films on Si substrates without crack generation.

Tuning the Electronic Structure of Sr2IrO4 Thin Films by Bulk Electronic Doping Using Molecular Beam Epitaxy

By means of oxide molecular beam epitaxy with shutter-growth mode, we fabricate a series of electron-doped （Sr1-xLax）2IrO4 （001） （x=0, 0.05, 0.1 and 0.15） single crystalline thin films and then investigate the doping dependence of the electronic structure utilizing in-situ angle-resolved photoemission spectroscopy. It is found that with the increasing doping content, the Fermi levels of samples progressively shift upward. Prominently, an extra electron pocket crossing the Fermi level around the M point is evidently observed in the 15% nominal doping sample. Moreover, bulk-sensitive transport measurements confirm that the doping effectively suppresses the insulating state with respect to the as-grown Sr2IrO4, though the doped samples still remain insulating at low temperatures due to the localization effect possibly stemming from disorders including oxygen deficiencies. Our work provides another feasible doping method to tune electronic structure of Sr2 IrO4.

Correlation between the Low-Temperature Photoluminescence Spectra and Photovoltaic Properties of Thin Polycrystalline CdTe Films

A dominant intrinsic luminescence band, which is due to the surface potential barriers of crystalline grains, and an edge doublet, which arises as an LO-phonon repetition of the e-h band, has been revealed in the low-temperature photoluminescence spectra of fine-grained obliquely deposited films. Doping film with In impurity leads to quenching of the doublet band, while further thermal treatment causes activation of the intrinsic band, the half-width and the blue shift of the red edge of which correlates with the maximum value of anomalously high photovoltage generated by the film.

Water and nutrient recovery from urine:A lead up trail using nano-structured In_(2)S_(3)photo electrodes

Developments of economic systems are critical for bio-regenerative life support systems in manned space missions.In this work we report on the feasibility of using two direct sunlight powered processes sequentially for the recovery of water and nutrients from urine.The work presents experimental evidence on nutrient and water recovery achieved using the proto-type designed and developed.We report the design and testing of a solar still which would serve on the nutrient recovery front.The cooled condensate from the solar still is fed into a solar powered electrolysis unit where nano-structured indium sulphide(In_(2)S_(3))thin films coated over fluorine doped tin oxide(SnO_(2):F)substrate serve as one of the working electrodes.The electrolysis takes place in the absence of an electrolyte which manifests as a technical achievement of our work.Our results show that the COD level in the recycled water is very low.The In_(2)S_(3)photo-electrodes are stable without any physical damage after the process.

Kinetic Monte Carlo Simulation of Deposition of Co Thin Film on Cu(001)

A kinetic Monte Carlo （kMC） simulation is conducted to study the growth of ultrathin film of Co on Cu（001） surface. The many-body, tight-binding potential model is used in the simulation to represent the interatomic potential. The film morphology of heteroepitaxial Co film on a Cu（001） substrate at the transient and final state conditions with various incident energies is simulated. The Co covered area and the thickness of the film growth of the first two layers are investigated. The simulation results show that the incident energy influences the film growth and structure. There exists a transition energy where the interracial roughness is minimum. There are some void regions in the film in the final state, because of the influence of the island growth in the first few layers. In addition, there are deviations from ideal layer-by-layer growth at a coverage from 0 - 2 monolayers （ML）.

Epitaxial Growth of Ga_XIn_(1-X) As Film by RF Sputtering and Physical Properties of the Films

Single crystal Ga X In 1-X As films have grown up on GaAs(100) substrate at 375℃ and on InP(100) substrate at 390℃, respectively, by the method of rf sputtering with using undoped GaInAs polycrystal as target. However, on Si(100) or Si(111) substrates at 260～390℃, even at 465℃, only polycrystalline films were obtained. In addition, the structure, composition, electrical characteristic and optical properties of the Ga X In 1-X As films were investigated using X ray diffraction (XRD), reflection of high energy electron diffraction (RHEED), energy dispersion analyzer of X ray (EDAX), Hall measurements and spectroscopic ellipsometry.

Fabrication and Properties of Double-Side Tl2Ba2CaCu2O8 Thin Film on CeO2 Buffered Sapphire Substrate

The double-side Tl2Ba2 CaCu2O8 （Tl-2212） superconducting thin films were fabricated on CeO2 buffered sapphire substrates. The reactive magnetron sputtering technique was used to grow CeO2 buffer thin films on sapphire substrates. Making use of the metal cerium as a sputtering source, the depositing rate is much higher compared with the CeO2 target. The Ti-2212 thin films on CeO2 buffered sapphire substrates were fabricated by adc magnetron sputtering and post-annealing process. The x-ray diffraction indicates that the thin film is pure Tl-2212 phase with the e-axis perpendicular to the substrate surfaces, and epitaxially grown on the CeO2 buffered sapphire. The critical transition temperature Tc is around 106K, the critical current density Jc is around 3.5 MA/cm^2 at 77K, and the microwave surface resistance R8 at 77K and 10 CHz of the film is as low as 390μ Ω.

Structural, Optical and Luminescence Properties of ZnO Thin Films Prepared by Sol-Gel Spin-Coating Method： Effect of Precursor Concentration

Transparent zinc oxide（ZnO） thin films are fabricated by a simple sol-gel spin-coating technique on glass substrates with different solution concentrations（0.3-1.2 M） using zinc acetate dehydrate [Zn（CH_3COO）_2·2H_2O] as precursor and isopropanol and monoethanolamine（MEA） as solvent and stabilizer, respectively. The molar ratio of zinc acetate dehydrate to MEA is 1.0. X-ray diffraction, ultraviolet-visible spectroscopy and photoluminescence spectroscopy are employed to investigate the effect of solution concentration on the structural and optical properties of the ZnO thin films. The obtained results of all thin films are discussed in detail and are compared with other experimental data.

Laser Damage Mechanisms of Amorphous Ta2O5 Films at 1064, 532 and 355nm in One-on-One Regime

Ta2O5 films are deposited on fused silica substrates by conventional e-beam evaporation. Surface topography and chemical composition are examined by atomic force microscopy （AFM） and x-ray photoelectron spectroscopy （XPS）. The calculation of electron structures of Ta2O5 and Ta2O5-x is attempted using a first-principle pseudopotential method within the local density approximation. The laser-induced damage threshold （LIDT） is performed at 1064, 532 and 355 nm in 1-on-1 regime, respectively. The results show that the LIDT increases with the wavelength increasing, which is in agreement with the wavelength effect. However, the LIDT results are not consistent with the empirical equation （I（λ）=aλm）, which may be attributed to the intrinsic absorption of Ta2O5 at the wavelengths of 532 or/and 355 nm. Moreover, different damage morphologies are observed when the films are irradiated at different wavelengths. It is concluded that the laser damage at 1064 nm is the defect dominant mechanism and at 355 nm it is the intrinsic absorption dominant mechanism, whereas at 532 nm it is the combined defect and intrinsic absorption dominant mechanism.