Rutherford backscattering and ion channeling-axial scans have been used to study lattice sites for several impurities implanted into A12O3. The case of Ga implanted in A12O3 is discussed and is shown to be substitutional on the Al sublattice. Additionally, the use of this technique in the study of precipitates in A12O3 is discussed with reference to Fe implanted A12O3 which was annealed in either oxygen or hydrogen.

The local structures of Zn and Co in solid solution in Na βN–alumina have been investigated using EXAFS spectroscopy. These additives are members of a group that must be incorporated in βN–alumina to stabilize the rhombohedral structure. It is found that they are tetrahedrally coordinated to four oxygen atoms. The N–O bond distances are larger than the Al–O distance in β–alumina and larger than the Al(2)–O distances in disordered crystals determined by x-ray and neutron diffraction. The bonds about individual ions and mixtures of ions are consistent with predictions from bond-strength-bonddistance theory. A preliminary study of Na β–alumina that has been implanted with in and annealed indicates that a substantial fraction of the Mn is tetrahedrally coordinated.

Damage nucleation in single crystals of silicon during ion irradiation is investigated. Experimental results and mechanisms for damage nucleation during both room and liquid nitrogen temperature irradiation with different mass ions are discussed. It is shown that the accumulation of damage during room temperature irradiation depends on the rate of implantation. These dose rate effects are found to decrease in magnitude as the mass of the ions is increased. The significance of dose rate effects and their mass dependence on nucleation mechanisms is discussed.

Ion backscattering and channeling of 2.0 MeV He+ has been used to observe the effects of excimer laser annealing on unimplanted and nitrogen implanted single crystal austenitic stainless steel. The laser annealing was done either in air or in flowing helium. In general, laser annealing resulted in a significant increase in lattice disorder of both unimplanted and implanted specimens. Laser annealing in helium atmosphere caused a near-surface decrease of disorder in the implanted specimens with, however, a higher dechanneling rate at greater depths. Channeling with nuclear reaction analysis shows that the as - implanted nitrogen occupies octahedral interstitial sites as evidenced by flux peaking along the <110> axis and a decreased signal along the <100> axis. A similar effect is observed after laser annealing in a helium atmosphere.

Bombardments of iron (commercially pure) with self-ions having energies of 50 and 100 keV were performed in–situ in a High–Voltage Electron Microscope at temperatures of 40 and 300 K. The resulting damage microstructures were examined at the irradiation temperature in the HVEM using 200, 300, 500 and 1000 keV electrons (damage threshold in Fe is ˜330 keV). Dislocation loop densities were measured as functions of ion dose, ion energy, irradiation temperature, electron dose (500 keV), and step annealing to room temperature. Loop geometries, size distributions, and nature (interstitial or vacancy) were also determined.

Accurate depth profiling of implanted hydrogen and its isotopes in metals is extremely important. Field ion microscopy and atom-probe techniques provide the most accurate depth profiling analytical method of any available. In addition, they are extremely sensitive to hydrogen. This paper reports our early work on hydrogen trapping at defects in metals using the Field Ion Microscope/Imaging Atom Probe (FIM/IAP). Our results deal primarily with the control experiments required to overcome instrumental difficulties associated with in situ implantation and the influence of a high electric field. Transmission Electron Microscopy (TEM) has been used extensively to independently examine the influence of high electric fields on emitters.

This paper discusses the application of the scanning transmission electron microscope (STEM) to the detection of segregation at interfaces via the monitoring of X-rays generated when the incident electrons interact with the segregant. Issues of spatial resolution and minimum detectable concentration are discussed. Specific examples, emphasizing the importance of probe size, sample thickness, and sample orientation, are presented.

Using a 0.5 nm diameter probe of 100 keV electrons, we have been able to detect significant changes in the transmission electron energy loss spectra in the region of valence shell and L23 shell excitation within a spatial extent of 0.4 nm of an Al-AlF3 interface. The spectra have been recorded with a dose significantly less than the critical dose for destruction of the AlF3.

The measurements presented here show the value of synchrotron light for determining both the electronic structure of overlayers, and the physical nature of the overlayer-substrate interface. A comparison is given between deposited layers and thermally stabilized layers. Estimates are also made of the bonding energy between the overlayer and substrate.

X-ray rocking curves and backscattering spectrometry with channeling have been employed to investigate epitaxial CoSi2 films grown on <111> Si substrates. Several preparation techniques were used: sputter cleaning, chemical cleaning, chemical cleaning with subsequent high temperature annealing, and e-gun evaporation on a cold or hot Si substrate, in situ annealing between 550–750°C for 30 min. Best results were obtained with chemical cleaning and pre-annealing at 925°C for 10 min, Co and Si codeposition on a 580'C hot substrate. For such samples, a typical x-ray perpendicular strain is -2.08%, and parallel strain is -0.11%. This parallel strain implies that the growth has been accommodated by dislocations with a spacing of ,∼ 2000 Å. The values of strain are consistent with the published lattice constants of Si and CoSi2 and Poisson's ratio of 0.28. The minimum yield in the channeling spectra of these films is. ∼ 3.6%, which is only slightly higher than that of <111> virgin Si.

Preliminary results on the performance of an analytical electron microscope (AEM) operating at 300 kV have been obtained and compared with the performance at 100 kV. Some features of the anticipated improvements for transmission electron microscopy (TEM) imaging, convergent beam electron diffraction (CBED), energy dispersive X-ray spectroscopy (EDS), and electron energy loss spectroscopy (EELS) have been studied from the aspect of materials science applications. The electron microscope used was a Philips EM430T operated with a LaB6 cathode and equipped with EDAX 9100/70 EDS and Gatan 607 EELS systems.

Heavily Sn-doped GaAs films have been grown by molecular-beam epitaxy and found to contain single-crystal Sn particles situated in the near-surface region of the epilayer GaAs. The morphology and chemical composition of the particles have been examined by using cross-section transmission electron microscopy combined with energy-dispersive x-ray spectroscopy. Different growth conditions were used to study the Sn-particle formation and high-resolution transmission electron microscopy was used to investigate microstructures. The observations are discussed in terms of several models previously proposed for these phenomena.

Chemical anodization and voltage contrast scanning electron microscopy (VC-SEM) have been used to identify electrically faulty structures in a bipolar test array. Direct comparison of these techniques was achieved by examining the same emitters with each method. VC-SEM is shown to be a useful technique for delineating E-C shorts because of its nondestructive and purely electrical nature. Further investigations by transmission electron microscopy revealed dislocations in many short-circuited emitters and occasionally in unshorted devices. This confirmed prior observations that crystallographic defects in silicon devices may sometimes be, but are not always, electrically active.

Many forms of low temperature alumina have been identified [1]. These are collectively referred to as transitional forms. The particular form depends strongly on the starting material (e.g., hydrated, thermally oxidized, alkoxide, etc.), the impurities present, and on thermal history. Although different forms of transition alumina are sometimes referred to as phases, none can be considered a true polymorph of corundum, i.e., α-alumina. Transformations from one form to another which occur upon heating are not reversible, although they are quite reproducible [2]. These different transitional structures are therefore considered to comprise different states of reordering. Figure 1 is a compendium of powder x-ray diffraction patterns from all known transitional aluminas and several aluminum hydroxides [3]. It i.s obvious that there are several crystallographic spacings which are nearly common to all forms.