We have studied the effect of ion implantation temperature on the nature of cleavage and layer transfer, and the electrical properties in hydrogen implanted p-Si. The lattice damage and the hydrogen concentration in the as-implanted Si and transferred Si films were analyzed with elastic recoil detection, respectively. Implantations performed at −140 °C [low temperature (LT)] and room temperature (RT) resulted in a variation in the thickness and surface morphology of the transferred layers. The transferred layer from room temperature hydrogen ion implantation was both thicker and atomically smoother than the transferred layer produced by −140 °C hydrogen implantation. The as-transferred layer obtained from RT-implanted p-Si wafer was n-type, but converted to p-type after annealing at 650 °C or higher. The transferred layer obtained from LT-implanted Si wafer was highly resistive even after high temperature annealing. These variations were observed to be correlated with the damage profiles measured by ion channeling; channeling data showed that the room temperature implantation provided a deeper and narrower damage distribution than that obtained from the −140 °C implantation. The nature of the implantation damage was evaluated with the aid of IR spectroscopy and was found to consist of Si–H defects. The type and population of these defects were observed to be dependent on the ion implantation temperature. In both room temperature and −140 °C implantations, the presence of the implantation damage facilitated the nucleation of Si–H defects that developed into H platelets, which were the precursor defects for the cleavage and the layer transfer.

A series of CoSb3 samples was synthesized at low temperature (∼150 °C) using modulated elemental reactants, with composition varying between Co-rich and Sb-rich, resulting in lattice parameters ranging from 9.023 to 9.090 Å. The samples were annealed in 100 °C increments from 200 to 600 °C, with lattice parameter, electrical resistivity, and Seebeck coefficient measured after each annealing. The spread of lattice parameters decreased with annealing (9.045 to 9.062 Å). The electrical resistivity of the samples changed from being nominally temperature independent, characteristic of a heavily doped semiconductor, to an exponential temperature dependence expected for a semiconductor, with band gaps of ∼0.1 eV. Seebeck measurements confirm the reduction in electrically active defect concentration with increasing annealing temperature. The nonequilibrium defect concentration trapped by low-temperature crystallization and varying composition, combined with the annealing studies, allowed a wide range of structural and electrical properties to manifest within a limited sample set.

To investigate the effect of tensile stress on the photochemical degradation efficiencies of polymers, a modified PVC polymer with Cp(CO)3Mo-Mo(CO)3Cp (Cp = eta5-C5H5) units along the backbone was synthesized. The polymer is photochemically reactive because the Mo-Mo bonds are photolyzed with visible light and the resulting radicals are captured with Cl atoms from along the polymer backbone. Of most importance from a mechanistic standpoint, the photochemical degradation reaction occurs in the absence of oxygen, which eliminates the kinetically complicating effect of rate-limiting oxygen diffusion. Tensile stress initially caused the quantum yield of polymer degradation to increase, but, after a certain point, additional stress caused a decrease in the quantum yield. This dependence of quantum efficiency on stress is consistent with a hypothesis in which stress affects the ability of the photochemically generated radicals to recombine. At low to moderate stress, the effect of stress is to increase the separation of the radicals (by recoil), thus decreasing their recombination probability. As the stress increases, however, segments of different chains align, which induces a higher degree of orientation and crystallinity in the polymer, which in turn makes diffusion more difficult. The efficiency of degradation is predicted to decrease accordingly because of decreased radical and/or trap mobility in the ordered polymer. Infrared and X-ray data are presented, showing that the degree of orientation and crystallinity in the polymer does indeed increase with increasing stress.

A thin-layer synthesis technique was used to synthesize bulk amounts of the metastable phase, RuSb(3), a novel compound with the skutterudite structure. The compound crystallized at 350 degrees C and was stable to 525 degrees C. When annealed above 550 degrees C, it decomposed into RuSb(2) and Sb. Rietveld refinement of X-ray diffraction data showed the presence of excess Sb residing in the interstitial site in the skutterudite structure. X-ray diffraction and thermal analysis experiments allowed us to examine the evolution of the sample as a function of annealing and determine the reaction pathway. The activation energy for the crystallization of the compound was determined to be 3 eV/nucleation event, while the activation energy for decomposition was approximately 8 eV.

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