As a consequence of strain relaxation, Ge coherent islands on Si(001) substrates evolve to different shapes as islands grow. By measuring the size and the strain simultaneously in a large population of individual islands using two simple and robust plan-view transmission electron microscopy-based techniques, we can identify island shapes easily because island shape is a function of strain. We briefly introduce the mechanisms of these two techniques. We then show that there is a metastable shape of Ge islands involved in the shape transition between pyramids and domes. The strain relaxation changes discontinuously as islands grow from pyramids to the metastable form and then finally to domes indicating that the shape transition between pyramids and domes is first order. We also show that the shape of this metastable island is a truncated dome and the faceted planes are {103}.

Preparation and characterization of novel dye-doped polyimide films for electrooptics is described. Thermal stabilities of donor-acceptor 2,5-diaryl oxazoles were evaluated by differential scanning calorimetry. Absorptive losses in thin films of Ultradel 9000D® doped with donor-acceptor oxazoles were measured by photothermal deflection spectroscopy. Absorptive losses at high doping levels may be explainable by dye-dye aggregation or dye degradation during the curing process. Lower doping levels, however, show losses of ≤ 3.0 dB/cm at 830 nm and ≤ 2.4 dB/cm at 1320 nm.