Annealing of isolated amorphous zones in silicon

In situ transmission electron microscopy has been used to observe the production and annealing of individual amorphous zones in silicon resulting from impacts of 200-keV Xe ions at room temperature. As has been observed previously, the total amorphous volume fraction decreases over a temperature range from room temperature to approximately 500 °C. When individual amorphous zones were monitored, however, there appeared to be no correlation of the annealing temperature with initial size: zones with similar starting sizes disappeared (crystallized) at temperatures anywhere from 70 °C to more than 400 °C. Frame-by-frame analysis of video recordings revealed that the recovery of individual zones is a two-step process that occurred in a stepwise manner with changes taking place over seconds, separated by longer periods of stability

In situ transmission electron microscopy studies of radiation damage in copper indium diselenide

The ternary semiconductor, CuInSe2 (CIS), is a promising semiconductor material for use in photovoltaic applications. Of particular interest is the high tolerance of this material to bombardment by energetic particles. This is of particular importance for photovoltaic applications in outer space where the lifetime of CIS-based solar cells has been found to be at least 50 times that of those based on amorphous silicon. In this paper we report on studies of the build-up of radiation damage in CIS during irradiation with Xe ions in the energy range 100–400 keV. Room temperature experiments indicate that dynamic annealing processes prevent the build-up of high levels of damage. However, for irradiation at a temperature of 50 K, the behaviour changes drastically with the material amorphising at low fluences. This effect is discussed in terms of defect mobility

Ordering in a fluid inert gas confined by flat surfaces

High-resolution transmission electron microscopy images of room-temperature fluid xenon in small faceted cavities in aluminum reveal the presence of three well-defined layers within the fluid at each facet. Such interfacial layering of simple liquids has been theoretically predicted, but observational evidence has been ambiguous. Molecular dynamics simulations indicate that the density variation induced by the layering will cause xenon, confined to an approximately cubic cavity of volume ~ 8 cubic nanometers, to condense into the body-centered cubic phase, differing from the face-centered cubic phase of both bulk solid xenon and solid xenon confined in somewhat larger (>=20 cubic nanometer) tetradecahedral cavities in face-centered cubic metals. Layering at the liquid-solid interface plays an important role in determining physical properties as diverse as the rheological behavior of two-dimensionally confined liquids and the dynamics of crystal growth

In situ transmission electron microscopy and ion irradiation of ferritic materials.

The intermediate voltage electron microscope-tandem user facility in the Electron Microscopy Center at Argonne National Laboratory is described. The primary purpose of this facility is electron microscopy with in situ ion irradiation at controlled sample temperatures. To illustrate its capabilities and advantages a few results of two outside user projects are presented. The motion of dislocation loops formed during ion irradiation is illustrated in video data that reveals a striking reduction of motion in Fe-8%Cr over that in pure Fe. The development of extended defect structure is then shown to depend on this motion and the influence of nearby surfaces in the transmission electron microscopy thin samples. In a second project, the damage microstructure is followed to high dose (200 dpa) in an oxide dispersion strengthened ferritic alloy at 500 degrees C, and found to be qualitatively similar to that observed in the same alloy neutron irradiated at 420 degrees C