Asymmetric reflections in which the beam paths are skew with respect to the sample surface have been used to characterize thin heteroepitaxial layers by double axis X-ray diffractometry. By utilizing reflections with Braqg cones which are partially embedded in the sample surface it is possible to tune to grazing the angles of incidence or emergence. Enhanced layer to substrate peak intensity ratio and narrower layer peak widths can be obtained. The technique is demonstrated using skew angle reflections 333, 133 and 044 from a 400Å GaInAsP layer on an InP substrate.

The structural perfection and defects of Ag films deposited by molecular beam epitaxy (MBE) on Si(ll1) and Si(001) substrates have been analyzed by x-ray diffraction, Rutherford Backscattering (RBS)/channeling and electron microscopy. In spite of the large lattice mismatch (∼25 %) between Ag and Si, relatively high-quality Ag single crystal films (6∼10 % surface minimum yield) were grown on both Si(111) and Si(001) substrates. The primary defects contained in the Ag/Si(111) were double-positioning twins. The quantity of twinning depends on the film thickness and the substrate condition. For both Ag/Si(111) and Ag/Si(001) epitaxial systems, a high density defect region was contained in the Ag film within ∼1000 Å of the interface. Ag films grown on misoriented Si(l11) substrates ( 4° off normal ) were misoriented by 0.5° towards the surface normal. Possible explanations of these defect formations associated with the large lattice mismatch are presented.

Controlled oxygen diffusion bonding experiments have shown that the formation of nickel aluminate spinel by solid state reaction between metallic Ni and α-A12O3 requires a certain oxygen activity, which is less than that of the Ni-NiO equilibrium. Under high vacuum bonding conditions the source of the oxygen required for spinel interphase formation was found to be oxygen initially dissolved in solution in the Ni. Equilibrium thermodynamic calculations confirmed the threshold oxygen activity dependence of spinel formation at the Ni/A12O3 interface, indicating ∼200 at. ppm oxygen is required in Ni before spinel can form at typical bonding temperatures. The predicted spinel layer thickness based on the calculated reaction equilibrium agrees extremely well with the measured thickness, further supporting the analysis.

Particles of a cubic A12O3 phase in an internally oxidized CuAl alloy were imaged by HREM. These particles are triangular platelets which lie on {111} planes of the copper matrix and have a diameter of about 100nm. They grow by migration of ledges. The platelets are always twinned parallel to their triangular base. At the A12O3 /Cu interface, the lattice of the A12O3 lies either parallel or in twin orientation relationship to the fcc Cu lattice. The interface is always parallel to {111} planes of the A12O3. The lattice parameter of the A12O3 is 10% larger than twice the lattice parameter of Cu. However, HREM micrographs and weak beam micrographs of the A12O3 /Cu interface do not show localized misfit dislocations. HREM image simulations of model structures yielded evidence that the A12O3 particles have a highly disordered spinel type structure. The simulations also indicate that a partly occupied layer of oxygen atoms terminates the A12O3 at the interface with Cu.

Critical voltage phenemona seen in electron diffraction can be used to determine the local composition of ternary semiconductors to a few per cent. Applications to (CdHg)Te and (AlGa)As are reported. Composition sensitive images can be obtained in various ways; techniques are discussed and results are presented.

In As diffusion process from AsSG films, As precipitation occurs at the AsSG/Si interface and functions as a diffusion barrier for As. This precipitation phenomenon is explained by the model based on the supersaturation of AsSG films.

We have studied the adsorption of molecular hydrogen onto the Si(111) 7 × 7 surface using UHV TEM at temperatures between room temperature and 780'C. We demonstrated that molecular hydrogen at 4 × 10−6 Torr dissociatively chemisorbed onto the Si(l11) surface at elevated temperatures and the stable hydrogenated Si(l11) surface is shown to be a strong function of temperature.

Si/Ge/Si (100) structures consisting of a thin epitaxial layer of Ge (1-64 monolayers) on Si and covered with a 5 nm overlayer of epitaxial Si were grown by MBE. The layers were analyzed by Rutherford backscattering(RBS)-channeling and transmission electron microscopy (TEM). For structures containing 4 or 8 monolayers of Ge, the channeling <110> angular scans showed unusual features that could be due to imperfect steering of the ion beam in the thin Si overlayer. Cross sectional TEN showed that the Ge epitaxy was good for these Ge thicknesses, but that for an average Ge coverage of 16 monolayers, Ge hillocks up to 90 monolayers thick occurred.

In a previous study we have examined the reduction of nickel oxide into nickel in NiO-ZrO2(CaO) aligned lamellar eutectic structures [1-2]. From the data which were obtained, we developed a model accounting for the fast reduction of nickel oxide; in particular it was shown that reduction takes place through the action of an electrochemical local cell, involving fast transport of oxygen to the sample surface through the cubic zirconia phase [2].