Transmission electron microscopy (TEM), and photoluminescence (PL) have been used to evaluate defects and the efficiency of defect-reduction techniques in structures with InAs quantum dots (QDs) for the 1.55 µm range grown at low substrate temperature (LT) using molecular beam epitaxy (MBE). We show that capping of the QDs with thin GaAs layer accompanied by growth interruption at 600oC (flash) allows to eliminate large islands, containing dislocations, while the smaller islands containing local defects (e.g. dislocation dipoles) still remain. If the flash procedure is accompanied with further depositing of thin AlAs cap layer, and followed by high temperature (~700oC) annealing (HTA), an almost complete elimination of defects is observed. The structures emit in the range of 1.55 µm due to lateral agglomerates of LTQDs. Simultaneously bright luminescence due to isolated QDs and GaAs matrix are detected at high excitation densities.

The response of a biological environment when in contact with an artificial material is primarily determined by the material surface properties such as composition, contact angle and free surface energy [1,2]. Owing to that, different treatments have been employed to improve the performance of biocompatible materials. In this sense, plasma-based techniques are very attractive because they enable the surface processing of materials with virtually any geometry preserving bulk properties. Furthermore, other characteristics make plasma treatment of particular interest in biomaterial processing. Those characteristics include, for instance, a) the possibility of using a large number of different chemicals to introduce any desired functional group on the surface, b) the treatment is performed in an intrinsically sterile environment and, c) different kind of materials (such as ceramics, metals and polymers) including those chemically inert can be treated.

Intermediate structures were trapped during the mesophase transition from lamellae to higher curvature structures in a sol-gel matrix. The target structures included normal hexagonally arranged cylinders and/or normal spheres in a cubic array distributed in a hydrophilic matrix. The present system is believed to be the first to trap these intermediates. Through solvent evaporation-induced self-assembly (EISA), mesostructured silica/diblock films with large characteristic length scales were prepared. The structure-directing agents were polystyrene-block-poly(ethylene oxide) (PS-b-PEO) diblock copolymers with high molecular weight, which are water insoluble and alcohol insoluble. We believe that no micellization took place in the present system; a disorder-to-order transition occurred due to the cooperative self- assembly of the diblock and silicates as the solvent preferentially evaporated from a film cast from a dilute homogeneous solution. During further preferential evaporation, the morphogenic effect of the increase of species concentration facilitates the mesophase development in the direction of a normal cubic to hexagonal to lamellar pathway. However, the morphogenic effects of both the decrease of the PS coil dimension and the siloxane condensation drive the mesophase development in opposite directions. The decrease of the PS coil dimension plays an important role in the present self-assembly process. Trapping of the intermediates and coexisting multiple mesophases are related to the facts that PS has high Tg and high hydrophobicity in particular, as well as to the fact that polymers have relatively low mobility in general.

The ionized cluster beam deposition of Al and Cu clusters has been investigated with a classical molecular dynamics simulation and the Metropolis Monte Carlo simulation. The spreading of the cluster has been studied as functions of cluster size and initial cluster energy. When the local area reached local melting spot on the surface, around the impact point of an energetic cluster, during a few ps, intermixing was easily achieved and a good epitaxial film with optimum bulk density was formed. For uniform film growth using cluster impact, it is necessary to make the local area temperature higher than melting temperature on the surface around the impact point of an energetic cluster.

Crystallographic and surface morphological characteristics of polycrystalline hcp Ti and Zr thin films were studied as a function of the homologous substrate temperature TS/TM and the thickness t of the films (28 nm ≤ t ≤ 380 nm). TS is the substrate temperature during deposition and TM is the melting point of the film's material. For the whole range of considered temperatures (0.14 ≤ TS/TM ≤ 0.48) Zr films presented a {0002} crystallographic orientation. As TS/TM increased, Ti films suffered a transition from a columnar grain structure with {0002} preferential crystallographic orientation to a cone-like-shape grain structure with {1011} preferential crystallographic orientation. Our results suggest that Zr films suffer a structural transition from Zone T to Zone II at temperatures similar to those predicted by Thornton's Structure Zone Model for thick films while Ti films do not have a microstructure typical of Zone II even for relatively high values of TS/TM, presenting a transition from Zone I to Zone T in the studied range of temperatures.

Polycrystalline copper films thicker than 100 nm were evaporated on silicon wafers with their native oxide under ultrahigh vacuum conditions leading to an rms roughness of ~2 nm of the copper film. X-ray photoelectron spectroscopy (XPS) revealed a clean copper surface with only traces of oxygen. The samples were exposed to air, leading to an oxide film consisting of CuO. TiO films were subsequently deposited onto the oxidized copper films from a resistively heated tungsten boat with the substrate at room temperature. The TiO films exhibited good adherence and were amorphous. XPS measurements revealed that the TiO films were contamination-free and that the first layers of TiO reduced the thin native oxide of the copper substrate from Cu(II) into Cu(I) or Cu(0) and transformed the TiO into TiO2 at the interface.

Optical and structural properties of InGaN/GaN quantum wells having growth interruption were investigated using high-resolution x-ray diffraction, photoluminescence and transmission microscopy. InxGa1−xN/GaN (x>0.25) six pair quantum wells used in this study were grown on c- plane sapphire by metalorganic chemical vapor deposition. The growth interruption was carried out by closing the group-III metal organic sources before and after growth of InGaN quantum well layers. With increasing the interruption time, the quantum dot-like region and well thickness decreases due to indium re-evaporation or thermal etching effect. As a result, PL peak position is blue-shifted and intensity is reduced. The size and number of V-defect did not vary with interruption time. The interruption time is not directly related with formation of the defect. The V-defect in quantum wells originates at threading dislocations and inversion domain boundaries due to higher misfit strain.

The evolution of the biaxial modulus of amorphous alumina thin films has been studied insitu during electron-beam evaporation at 400°C on Si and sapphire substrates. A constant value of 197 ± 30 GPa was measured up to a thickness of 1.17 μm when depositing at 3 Å/s. This value was identical to that of films thinner than 0.30 μm deposited at an average rate of 6 Å/s. Above 0.30 μm, the modulus in these films decreased continuously to a value of 50 ± 8 GPa at a final thickness of 2.05 μm. Based on their refractive indices, the films deposited at 6 Å/s are 30% less dense than those deposited at 3 Å/s. This density deficit is insufficient to account for the modulus decrease; the remainder is probably the result of slit-like microcracks.

Nanoindentation experiments have been performed to assess the mechanical behavior of chromium nitride (CrxNy) thin films sputtered in different deposition geometries and with varying Ar and N2 pressures. The hardness and elastic modulus of chromium nitrides are of great interest with regard to their applications. In the present work, two different deposition geometries, i.e. multi-substrate and confocal, were used to sputter (DC magnetron) a CrxNy layer on Si (100) wafers at varying nitrogen flow rates. The results of the nanoindentation experiments indicate that, over a similar argon and nitrogen regime, the CrxNy films grown in a multi- substrate geometry exhibit higher hardness and elastic modulus on the average than those grown in the confocal geometry. Furthermore, it was found that in the multi-substrate geometry the hardness and elastic modulus of the films were significantly higher than those in the confocally deposited films for a specific regime of the nitrogen flow rate (10-14 sccm). Finally, observations of the mechanical properties trends could be correlated with a higher degree of anisotropic stress for films grown in the multi-substrate in comparison to the confocal geometry.

Titanium dioxide (TiO2) films were deposited on (a) non-alkali glass, (b) MgO (100) and (c) SrTiO3 (100) single crystals by rf reactive magnetron sputtering using a Ti metal target. X-ray diffraction and a pole figure analysis revealed that TiO2 films on the (a) were anatase polycrystals with <101> preferred orientation, whereas heteroepitaxial growth of anatase TiO2 was observed on the (b) and the (c) substrates. FE-SEM analyses on the crystal habit of the firm surfaces showed that the substrate temperature during the deposition (Ts) heavily affected the microstructure and surface morphology of the heteroepitaxially grown films, which could be clearly explained in terms of “Thornton's zone model” or “epitaxial growth model of 2-dimensional ledge or kink modes” considering the normalized Ts by the phase transition temperature from anatase to rutile.

ZnO and SiO2 thin films coated on plastic materials were investigated for the protection against solar ultraviolet (UV) radiation and the hard coating. Using diethylzinc (DEZ) as the organic zinc material, we attempt to deposit ZnO thin films on polycarbonate (PC) resin at room temperature by the cathode deposition technique of the plasma enhanced (PE) CVD method. It was found that the rf power and the substrate temperature intensively influenced on the deposition rate. The deposition rate increased with the rf power up to 100W, but decreased with the RF power above 100W, and also decreased with increasing the substrate temperature. In a xenon arc weatherability test, the ZnO-coated PC plates exhibited remarkable protection characteristics against UV radiation. They kept a smooth surface and no- coloring even if UV light irradiated for 1000 hours. Moreover, SiO2film deposited from tetraethoxysilane (TEOS) was over-coated on the ZnO film / PC plates. These films showed a drastic improvement in the hardness. Therefore, these films are expected as the UV-cut and hard coating for the automotive parts.

Epitaxial TaN(001) films have been successfully grown on MgO(001) single crystal and TiN(001) buffered Si(001) substrates by pulsed laser deposition method. Crystalline TaN layers of about 100 nm thick were deposited under a base pressure of 5 × 10−6 Torr and at substrate temperatures ranging from 500°C to 700°C. X-ray diffraction results suggested that stoichiometric TaN films with cube-on-cube <001>TaN∥<001>MgO heteroepitaxy are obtained in this temperature range. Plan-view and cross-sectional electron microscopy analysis revealed excellent structural quality and sharp interface boundary. TaN films grown on TiN(001) buffered Si(001), however, showed a mixture of TaNx (with x ≤ 1) components. Although the (001)-orientated TaN is always present prominently, the nitrogen deficient TaNx components are often co-existed in the films and show up as a broad peak in the X-ray diffraction profile. Stoichiometric and single phase TaN(001) films can only be obtained in a narrow temperature window at around 550oC and heteroepitaxial relation <001>TaN∥<001>TiN∥<001>Si has been demonstrated.

We found the correlation between microstructure and surface evolution in the crystallization of amorphous α-Fe2O3/α-Al2O3(0001) thin films using real-time synchrotron x-ray scattering and atomic force microscope. The amorphous precursor is crystallized to the epitaxial α-Fe2O3 grains in three steps; i) the growth of the well aligned α-Fe2O3 interfacial islands on α-Al2O3(0001), ii) the growth of the misaligned, homoepitaxial, α-Fe2O3 grains on the well aligned grains ( > 400 °C), and iii) the nucleation of the heteroepitaxial misaligned grains directly on the α-Al2O3substrate ( > 600 °C). The surface roughing is caused by the microstructure evolution during the crystallization of the amorphous precursor films.

Nucleation and growth has been studied during tungsten (W) atomic layer deposition (ALD) on oxide surfaces. Auger electron spectroscopy (AES) was utilized to examine the deposition of W during the sequential (A) WF6 and (B) Si2H6 reaction cycles that define W ALD. The AES results displayed an initial nucleation period of ∼10 AB cycles to deposit one tungsten monolayer on SiO2. Subsequently, the W and Si AES signals grew and oscillated dramatically versus WF6 and Si2H6 exposures. The increase in the W AES signal in the growth region was consistent with a W ALD growth rate of 3.5 Å per AB cycle. An examination of the oxygen and tungsten AES signals versus AB cycles indicated that W ALD displayed nearly ideal “layer-by-layer”, Frank- van der Merwe growth after the nucleation period. On Al2O3, the AES results displayed a much shorter nucleation period for W ALD. Only 3 AB cycles were required to deposit one tungsten monolayer. Subsequently, the tungsten film grew at a rate of 3.6 Å per AB cycle. The initial nucleation period and growth mechanism during ALD are important because they will affect the roughness of the resulting ALD film.