Diamond films were deposited in a microwave plasma chemical vapor deposition (MPCVD) system on Ta substrates using a mixture of hydrogen and methane gases. The films were grown for varying lengths of time to provide samples with no diamond growth to a continuous diamond film. These films were analyzed using X-ray photoelectron spectroscopy (XPS) in order to understand the time dependent interactions between the substrate and the incoming carbon flux. Photoelectron peaks in the Ta 4f, C Is and Ols regions have been analyzed. In the initial stages of growth, a layer of carbide forms on the substrate. As the substrate becomes supersaturated with carbon, graphite starts to form on the surface. A diamond peak begins to appear after about 30 Minutes of deposition.

The quality of diamond thin films on nondiamond substrates is often poor because of large number of defects such as dislocations, twins, stacking faults and grain boundaries. The diamond films often exhibit poor adhesion on nondiamond substrates because of large differences in interatomic potentials between the film and the substrate. The epitaxial nature of the film is determined not only by lattice matching but also by gradient in interatomic potentials across the interface. We have used computer simulations to study energetics of different geometric configurations of C / Si interfaces. The simulations predict that an C / SiC interface had the least energy and therefore the preferred interface configuration. This is in concordance with experimental deposition of C on Si which resulted in formation of an SiC layer in between C and Si.

We investigated the effects of the substrate temperature (Ts) on the crystallization and the development of texture of Mn-Zn ferrite thin films on SiO2/Si (100) under ion bombardment during ion beam sputtering. As-deposited films showed ferrimagnetic properties in spite of their crystallographic structure of wustite. The crystallographic structure of as-deposited films changed from (111) wustite structure to (222) spinel structure as oxygen partial pressure increased. The (222) preferred orientation seems to originate from oxygen-deficit ambient and preferential resputtering of oxygen ions in films during sputtering. The interplanar distance of the films deposited without oxygen flow decreased with increasing Ts due to release of compressive stress. The saturation Magnetization (Ms) of the film had maximum value at about 275°C, while the resistivity was almost of the same value irrespective of Ts. The unusual fact that crystallization and preferred orientation were less progressed at higher Ts was discussed.

Lanthanum aluminate (LaAlO3) has been used as a substrate material for depositing Ba2YCu3O7−x (YBCO) films. In the present study, chemically derived epitaxial LaAlO3 thin films were used for depositing epitaxial YBCO films. These epitaxial LaAlO3 films were deposited on both (100) SrTiO3 and (100) LaAlO3 single crystal substrates by pyrolysis of a mixed nitrate precursor. Crystallization of LaAlO3 on lattice-Matched substrates occurs at below 650°C, whereas crystallization on non lattice-Matched substrates occurs at much higher temperature. The average surface roughness of these LaAlO3 films can be as low as 7Å. The YBCO films derived from metalorganic deposition of metal trifluoroacetate precursors were deposited on these epitaxial LaAlO3 films on SrTiO3 substrates. The resultant YBCO films have critical current densities of > 2 × 106 A/cm2 at 77K and zero field. Transmission electron microscopy of these films shows that they are highly epitaxial yet have pore of about 15–30 nm in size. Chemically derived LaAlO3 films also were used to planarize stepped substrates.

Yttrium aluminum garnet (YAG) films were produced by reacting thin Y2O3 layers with single-crystal Al2O3 substrates. Y2O3 films were deposited using pulsed-laser deposition (PLD), which produced smooth textured films on specially prepared (0001) α-Al2O3 substrates. Solid-state reaction of the Y2O3 with the Al2O3 was induced by specific heat treatments. Transmission-electron microscopy was used to characterize the reaction products of each heat treatment. For a reaction temperature of 1200°C, cross-sectional TEM specimens revealed the development of Monoclinic Y4Al2O9 at the interface between the Y2O3 and the Al2O3. Development of YAG was seen to occur at the interface between the Al2O3 and the Y4Al2O9 for a slightly higher reaction temperature of 1250°C. The Metastable Y4Al2O9 phase and the Y2O3 phase were found to be consumed at higher reaction temperatures to form the equilibrium Y3Al5O12 (YAG) phase. The Morphology of the YAG film was characterized by scanning-electron microscopy.

The chemical compatibility between MoSi2 and Al2O3 at 1300° C was examined using sputter deposited MoSi2 films, 0.7 μm thick, on sapphire and on polycrystalline alumina. The oxidation behavior of the sputter deposited films was found to be identical to that of bulk MoSi2. The oxidation products of the MoSi2 are Si oxides and lower suicides of Mo. MoO3 is formed and sublimes at the free surface. Oxidation is found to occur at the SiO2/MoSi2 interface. Just beneath this interface, suicides of mo and two oxidation states of Si were identified. No reaction between MoSi2 and alumina was found. In the case of a sapphire substrate, after mo was completely eliminated from the interface, silica reacted with the substrate and eventually phase separated into high- and low-silica phases. Nucleation, growth and coalescence of high-silica precipitates were observed.

We demonstrate the heteroepitaxial growth of thin films of SrTiO3 prepared by the method of Metallo-organic decomposition on LaAlO3 substrates. The SrTiO3 films are prepared by spin coating and thermal decomposition of a solution of Metallo-organic precursors on single-crystal, <100> oriented, LaAK>3 substrates. Subsequent heat treatment at 1100 – 1200 °C for 1 h results in the epitaxial alignment of the SrTiO3 films with respect to the LaAlO3 substrate.

The degree of alignment of the films appears to depend on their thickness, with thinner films showing better alignment (as determined by ion-channeling measurements). This behavior is interpreted as a result of the competition between solid-phase epitaxy and random nucleation, observed during the crystallization of films prepared by Metallo-organic decomposition. However, since thinner films have been prepared by dilution of the precursor solution, there is also the possibility that the concentration of the precursor solution may influence the crystallization behavior of the films.

The potential influence of the precursor formulation on the crystallization mechanism is discussed.

We investigate the microstructural evolution and epitaxial alignment of thin films of LiNbO3 deposited by the Metallo-organic decomposition method on Al2O3. The LiNbO3 films are prepared by spin coating and thermal decomposition of a solution of Metallo-organic precursors on single-crystal, <0001> oriented, Al2O3 substrates, followed by heat treatment in a quartz tube furnace at temperatures ranging from 500 to 1000 °C.

X-ray diffraction analysis reveals that films heat treated at 600 °C for 1 h are highly oriented along the c-axis direction, but the alignment is not good enough to permit channeling of 2 MeV He++ particles. Heat treatment at 900 °C improves significantly the epitaxial alignment as determined by ion-channeling measurements. However, concomitantly with the improvement in crystal orientation, the films break up into a network of LiNbO3 grains, partially uncovering the Al2O3 substrates along grain boundaries. Pole figure analysis shows that all the grains share the same in-plane orientation.

Magnesium aluminate (MgAl2O4) is a potential dielectric material in Ba2YCu3O7−x (BYC) devices. In the present study, epitaxial MgAl2O4 films were deposited on (100) SrTiO3 single crystal substrates by pyrolysis of chemical precursors. Two precursors were used: one was a mixed nitrate precursor, and the other was MgAl2(OC3H7)8. Crystallization of MgAl2O4 on lattice-Matched substrates is observed at 700°C. The average surface roughness of these MgAl2O4 films is about 6Å. These chemically-derived MgAl2O4 films have demonstrated the potential for planarization by metalorganic deposition. The relationship between the processing parameters and the surface morphology of these MgAl2O4 films will be discussed.

The structure and morphology of r-axis (1012) and c-axis (0001) sapphire (a-Al2O3) surfaces were studied with Low Energy and Reflection High Energy Electron Diffraction (LEED and RHEED) and Atomic Force Microscopy (AFM). Following heat treatments at 1000°C in 5×10-7 torr O2, both surfaces exhibited (1×1) diffraction patterns. Regular step-terrace structure was observed on the (1012) surface with the AFM, but no step structure was visible on the (0001) surface. The initial growth of magnesium overlayers dosed onto the (1012) surface at 25°C in ultra-high vacuum was monitored with RHEED and the chemical interactions at the Mg / Al2O3 interface were characterized with X-ray Photoelectron Spectroscopy (XPS). During the initial deposition, very little interaction between mg and the Al2O3 substrate occurs and a very abrupt interface is formed. At larger mg doses, a textured polycrystalline mg overlayer is produced. Annealing the mg film above 300°C causes some oxidation of mg at the Mg / Al2O3 interface, but most of the mg desorbs from the surface.

We have grown thin films and multilayers of several ferrite materials with the spinel structure by pulsed laser deposition of stoichiometric targets. Epitaxial films can be grown on a variety of substrates including MgO, Al2O3, MgAl2O4, Y-stabilized ZrO2 (YSZ) and SrTiO3. Films on Mg- and Al-containing substrates have a low saturation Magnetization, Ms, while films on YSZ and SrTiO3 exhibit bulk values of Ms. The anisotropy can be lowered by a post growth anneal, resulting in a film with a permeability of 28.

In this paper, we describe the relation of the surface morphology of GaP grown by chemical beam epitaxy (CBE) and interrupted cycle chemical beam epitaxy (ICCBE) to the deposition conditions on (001) Si. The films were examined with scanning electron Microscopy (SEM) and atomic force Microscopy (AFM). Initial stages of the films grown by CBE using triethylgallium (TEG) and tertiarybutylphosphine (TBP) examined by SEM reveals in addition to GaP nuclei at 10–100 nm scale, whiskers of typically 100 nm diameter at their bases. AFM Measurements yield an average height of these whiskers of 50 nm that self-terminate and are incorporated into the GaP film upon further growth without loss of epitaxy as determined by x-ray diffraction. Nevertheless, the whiskers are a possible source for defects and surface roughness in thicker films. Whisker formation can be suppressed under conditions of ICCBE by the addition of hydrogen flow, sealing the silicon surface by a smooth thin film of GaP.

Results of Si1-xGex deposition on oxide-coated Si substrates using a PE-VLPCVD (Plasma-Enhanced Very-Low-Pressure Chemical Vapor Deposition) reactor are presented. Thin layers of poly-Si1-xGex deposited with SiH4 and GeH4 at ≤ 600°C had low C and O levels. Two growth modes were examined at 500°C: plasma-initiated thermal growth (VLPCVD) and full plasma-enhanced deposition (PE-VLPCVD). In both cases, Ge incorporation increases sublinearly with gas ratio, growth rates increase with Ge content, and the transition temperature between polycrystalline and amorphous deposition is lower for Si1-xGex than Si. On the other hand, compared to thermal growth, plasma-enhanced deposition promotes not only higher growth rates but also improved structural properties such as smoother surface Morphology, More columnar and oriented grains, and the unique feature of direct deposition onto oxide.

Molecular dynamics simulations are performed of low-energy ion irradiation of two-dimensional Cu islands on a Cu(111) surface. The irradiation of the surface with low-energy particles influences the mobility of the atoms in the surface region and therefore may alter the thin film growth Mode. The effect of 100 eV Ar+ ions incident at grazing angles is limited to situations in which the ions hit the edges of the islands. In Most cases the islands lose one or two atoms. Changing the angle-of-incidence or changing the type of the incident particle has a strong influence on the size distribution of the two-dimensional islands.

The observations of the as-solution-grown GaAs (001) vicinal surfaces yield three kinds of Microtopologies. Each of them develops in a certain range of growth temperature. In a low temperature range (492° C…600° C) we observe parallel growth steps with heights of one Monolayer. In a medium range, a network consisting of two sets of growth steps with larger heights is observed. At high growth temperatures (780° C…850° C) we find growth surfaces that are atomically rough. IMplications of these findings for modelling the crystal growth will be discussed.

The growth of Ni on Au (100) has been investigated by MBE. It has been found that a Metastable BCT Ni (100) phase is coherent with the substrate up to a thickness of 5 ML. Then a structural transformation analogous to a raartensitic transition occurs, and the structure becomes FCC Ni (110). We show that the interfacial stress is progressively relieved by a high density of stacking faults, as was predicted by Bruinsma and Zangwill for epitaxial overlayers with a large Misfit.