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The impact of the Ga/N ratio on the structure and electrical activity of threading dislocations in GaN films grown by molecular-beam epitaxy is reported. Electrical measurements performed on samples grown under Ga-rich conditions show three orders of magnitude higher reverse bias leakage compared with those grown under Ga-lean conditions. Transmission electron microscopy (TEM) studies reveal excess Ga at the surface termination of pure screw dislocations accompanied by a change in the screw dislocation core structure in Ga-rich films. The correlation of transport and TEM results indicates that dislocation electrical activity depends sensitively on dislocation type and growth stoichiometry.

A simple metallic bonding structure, has been developed consisting of a pure metal Nb and an alloy containing Sn, which can be employed to bond a semiconducting laser device and/or a silicon integrated circuit die to a submount with Au–Sn solder. Differential scanning calorimetry, transmission electron microscopy, and scanning electron microscopy reveal that the Nb layer acts effectively both as an adhesion layer to SiO2 and diamond submounts and as a perfect diffusion barrier against Au–Sn solder. The metallization structure shows no indication of dewetting of the Au–Sn solder. The excellent bonding characters have been attributed to the unique metallurgical properties of Nb.

Epitaxial ferroelectric SrRuO3/Pb(Zr0.52Ti0.48)O3/SrRuO3 heterostructures have been fabricated employing isotropic metallic oxide electrodes on (100) SrTiO3 and (100) Si with an yttria stabilized zirconia buffer layer. The structures have been grown in situ by 90° off‐axis sputtering, which allows the growth of uniform stoichiometric films over large areas with excellent step coverage. X‐ray diffraction, Rutherford backscattering spectroscopy, and cross‐sectional transmission electron microscopy reveal high crystalline quality and coherent interfaces. They exhibit superior fatigue characteristics over those made with metal electrodes, showing little degradation over 1010 cycles, with a large remnant polarization.

The two fold degeneracy inherent to epitaxial growth of high Tc films on (101) perovskite substrates has been removed successfully. This is demonstrated by single domain, (103) oriented La2−xSrxCuO4 films of 0.04≤x≤0.34 on vicinal (101) SrTiO3 substrates using 90° off‐axis sputtering. (101) substrates that have the surface normal rotated about [010] by 0.5°–3.5° produced essentially single crystal films with the c‐axis direction determined by the sense of the miscut. Misoriented antidomains (103)’ have been eliminated effectively to a percentage less than 1 part in 104. The mechanism for symmetry breaking is understood on the basis of a surface step model in which the energetics promoting single domain growth is derived from nucleation and epitaxy on the (001) face found at surface steps of vicinal substrates. Furthermore, the incommensuration of the c axis interplanar spacings with the a, b, plane lattice parameters in the La2−xSrxCuO4 structure provides a natural selection of (103) domains over (103)’ d...

The surface plasmon (SP) excitations of gold/silica nanowire, investigated by electron energy-loss spectroscopy in conjunction with scanning transmission electron microscopy, are found to be anisotropic with stronger SP intensities observed along the transverse direction of the nanowire. This indicates that the charge carriers generated near the surface of the nanowires by the decay of SP resonance play a significant role to the enhanced photoconductivity. This conclusion is reaffirmed by the polarization dependent photoconductivity measurement.

A “step-edge” model has been proposed to explain the growth of solid nanotips of aluminum nitride (AlN) and indium nitride (InN) grown by thermal and metal organic chemical vapor depositions, respectively. The model predicts a set of apex angles that solid AlN and InN nanotips can have. A statistical distribution of the apex angle in InN nanotips indicates the discrete set of apex angles and its probability of nucleation.

We have studied the microstructures of epitaxial YbBa2Cu3O7 superconducting films grown on SrTiO3[100] and [110] substrates by a new liquid‐gas‐solidification processing technique. Films grown on SrTiO3[100] and [110] substrates are epitaxially oriented with [001] and [110] axes normal to the film surface. Twinned domains of ∼200 A in size are observed in the [001] oriented films. Most defects observed can be attributed to the presence of stacking faults along the c axis. The presence of Cu‐O bilayer defects is also observed. Rapid oxygen diffusion in the liquid phase is found to play an important role in the microstructure of the thin films.

We compare the superlattice modulation, microstructure, and epitaxy of Tl2Ba2Ca2Cu3O10 thin films grown on MgO [100] and SrTiO3 [100] substrates by dc diode sputtering. Films grown on MgO were found to be quite clean with the c axis perpendicular to the substrate. However, no in‐plane orientational relationship to the substrate was found. Films grown on SrTiO3, on the other hand, showed very good epitaxy to the substrate despite the presence of second phases. Films grown on MgO also exhibited a longer coherence length of the superlattice modulation than those grown on SrTiO3 under identical conditions.

The pyrolysis of organic dianhydrides (e.g., 3,4,9,10‐perylenetetracarboxylic dianhydride) in an evacuated system results in the loss of hydrogen, CO, and CO2 and the deposition of a chemically inert, metallic‐appearing mirrolike film. The films are highly conducting (σRT250 Ω−1 cm−1) and can evidence either metallic or semiconducting behavior, depending on the preparation temperature. Superconducting films are obtained when niobium is used as a dopant. Preparation of films on doped silicon semiconductor chips results in the formation of p‐n junctions. ESR spectra exhibit a moderately strong line at g=2.0025. The resonance intensity remains almost constant to 20 °K, characteristic of a highly delocalized spin system.