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Structural and electronic characteristics of KY(WO4)2 (KYW) (010) crystal surfaces have been studied using reflection high-energy electron diffraction (RHEED) and x-ray photoelectron spectroscopy (XPS). The results indicate that the crystal structure and chemical composition of the mechanically polished pristine surface is stoichiometrically well maintained as expected for KYW crystals. Combined measurements of RHEED and XPS as a function of 1.5 keV Ar+ ion irradiation of the KYW (010) surfaces indicate amorphization, partial loss of potassium atoms, and partial transformation of chemical valence state of tungsten from W6+ to a lower valence state, W0 state predominantly, which induces electronic states at the top of valence band. [ABSTRACT FROM AUTHOR]

Optical quality Pb2MoO5 single crystals were grown by the Low Thermal Gradient Czochralski (LTG Cz) technique. The resulting Pb2MoO5 crystals had diameters of 40–50 mm and lengths of ~100 mm. The phase composition of the grown crystals was identified by X-ray single crystal structure analysis; the space group is C2/m and a = 14.2221(11), b = 5.7852(5), c = 7.3262(6) Å, β = 114.168(2)° and Z = 4 (R1 = 0.0336). Pb2MoO5(20−1) substrates were prepared by cleavage, and the surface properties were evaluated by RHEED and AFM. The superposition of wide Kikuchi lines and crystal reflexes was found by RHEED. The AFM measurements indicate a surface roughness as low as ~0.2 nm. Thus, atomically smooth surfaces of Pb2MoO5 were formed by cleavage. [ABSTRACT FROM AUTHOR]

Structure and optical characteristics of nickel (Ni) single crystal (100) surface and thin films have been evaluated by the combined use of reflection high-energy electron diffraction (RHEED) and spectroscopic ellipsometry (SE). Nickel films were fabricated by thermal evaporation at 100°C while Ni single crystal was grown by vertical Bridgman method. RHEED analysis indicates that the grown Ni films were polycrystalline. Spectral dependencies of refractive index n(λ) and extinction coefficient k(λ) determined in the spectral range λ ~ 250-1030 nm indicate the typical behavior of metals. The refractive index of Ni films is found to be slightly higher compared to that of Ni(100) crystal. [ABSTRACT FROM AUTHOR]

Molybdenum nitride films γ-Mo2N/Si have been fabricated with reactive magnetron sputtering in (N2 + Ar) gas mixture. Phase composition of the films has been defined with reflection high energy electron diffraction. Refractive index and extinction coefficient of γ-Mo2N have been evaluated with laser ellipsometry at λ = 632.8 and 488.0 nm. Upper limit of γ-Mo2N film thickness measurable with laser ellipsometry has been found to be ~80 nm. [ABSTRACT FROM AUTHOR]

Molybdenum oxide (MoO3) exhibits interesting structural, chemical, electrical, and optical properties, which are dependent on the growth conditions and the fabrication technique. In the present work, MoO3 films were produced by pulsed-laser deposition and dc magnetron sputtering under varying conditions of growth temperature (Ts) and oxygen pressure (pO2). The effect of growth conditions on the structure and chemical properties of MoO3 films was examined using x-ray diffraction, reflection high-energy electron diffraction, x-ray photoelectron spectroscopy, and infrared spectroscopic measurements. The analyses indicate that the microstructure of Mo oxide films is sensitive to Ts and pO2. The growth conditions were optimized to produce stoichiometric and highly textured polycrystalline MoO3 films. A comparison of the microstructure of MoO3 films grown using pulsed-laser deposition and sputtering methods is also presented. [ABSTRACT FROM AUTHOR]

A study of the surface structure and electronic properties of (010) KGd0.95Nd0.05(WO4)2 (Nd:KGW) using RHEED analysis and XPS is presented. It is shown that Nd doping has a negligible effect on the core levels of the basic elements. A bombardment of the Nd:KGW crystal with 3-keV Ar ions results in surface amorphization accompanied by the generation of tungsten ions in lower valence states. [ABSTRACT FROM AUTHOR]

X-ray photoemission spectroscopy (XPS) measurements have been executed for TlTiOPO4 to elucidate the general features in the electronic structure of the KTiOPO4 family compounds. The peculiarities of the valence band structure have been discussed for the crystals. The persistence of core level binding energy differences O1s–P2p and O1s–Ti2p3/2 has been detected in TlTiOPO4 and KTiOPO4, which relates well with the constancy of averaged P–O and Ti–O chemical bond lengths in this crystal family. The superstructure ordering of the TlTiOPO4 surface subjected to polishing and annealing has been detected by reflectance high energy electron diffraction (RHEED). From comparison of surface crystallographic properties of TlTiOPO4 and KTiOPO4, the most typical superstructure indices have been revealed. [ABSTRACT FROM AUTHOR]

Yttrium oxide (Y2O3) films with an average crystallite-size (L) ranging from 5 to 40 nm were grown by sputter-deposition onto Si(100) substrates. The optical properties of grown Y2O3 films were evaluated using spectroscopic ellipsometry measurements. The size-effects were significant on the optical constants and their dispersion profiles of Y2O3 films. A significant enhancement in the index of refraction (n) is observed in well-defined Y2O3 nanocrystalline films compared to that of amorphous Y2O3. A direct, linear L-n relationship found for Y2O3 films suggests that tuning optical properties for desired applications can be achieved by controlling the size at the nanoscale dimensions. [ABSTRACT FROM AUTHOR]

Lead phthalocyanine (PbPc) thin films deposited by vacuum sublimation with Ar low-temperature electron cyclotron resonance (ECR) plasma treatment are investigated by means of reflection high-energy electron diffraction, atomic force microscopy, infrared spectroscopy, x-ray photoelectron spectroscopy and spectral ellipsometry. The intensity of plasma treatment is varied by the radio-frequency power input and the value of electrical bias applied to the sample. The films grown with and without plasma assistance are compared. The plasma intensity is considered to significantly influence the crystalline structure, surface morphology and film composition. At a low intensity the plasma assistance is analogous to vacuum annealing of films. At a medium intensity, a porous polymer matrix filled with PbPc in crystalline phases (monoclinic and triclinic) is formed in the films. At a high intensity, all the films consist of a compact polymer matrix, similar to a glassy solid, with small inclusions of PbPc molecules. The succession of PbPc molecule destructions in the growing film layer with plasma intensity increase is established by IR spectroscopy. The mechanism of polymer matrix formation is suggested. [ABSTRACT FROM AUTHOR]