Annealing experiments

When the samples were etched mildly, the anomalous increase upon annealing was not observed. In an isothermal annealing experiment performed at 423 K for As—H complexes, the exponential decay given by Eq. (3) was verified for a 50 times reduction in concentration. In Fig. 11 the results of a series of 30 min isochronal anneals are shown for each of the donor-H complexes. The curves are given by Eq. (3) with an assumed attempt frequency of 1013 s-1 and binding energies of 1.32 eV for P—H and 1.43 eV for As—H and Sb—H. 

Awareness of the very rapid migration of the H+ species provides a valuable orientation for the interpretation of many experiments. One of the most important of the examples discussed in the later parts of Section 3 has to do with the binding energy of the complexes AH that hydrogen forms with various shallow acceptors A. The lifetime of such a complex with respect to thermal dissociation into H+ and A can be measured in some types of annealing experiments, and this lifetime is related to the... 

Other reverse-bias annealing experiments have been published that can be analyzed in the same way. Tavendale et al. (1985) used 10 ft cm boron-doped silicon passivated by exposure to plasmas containing or 2H. Schottky diodes formed with such specimens showed breakup of BH under heating at 80°C with reverse bias however, there was a persistence of passivation in the first two or three microns that must be attributed to some sort of near-surface reservoir of hydrogen. This effect was absent in an annealing experiment on a junction diode with an -type surface... 

What makes this acceptor interesting is that its concentration can be varied reversibly over a wide range. Thermal quenching and annealing experiments showed that the acceptor must be due to a center that undergoes dissociation/recombination reactions. The following arguments led to... 

Since A B is found from bias annealing experiments to be a function of nBT (Street and Kakalios, 1986 Kakalios and Street, 1987), then rcreat or rann (or both) will similarly depend on nBX. r is the rate of defect creation or removal and therefore is related to hydrogen motion it follows that >H will also be a function of nBx. 

The annealing experiments on spin cast films near Tg show a drop in Ie/Im, although after 24 hours of annealing Ie/Im is still higher than for a solvent cast film that has undergone no radial stress. This implies that non-equilibrium chain structures still exists in the spin cast films even after long annealing times. 

Similar results have been presented by Miller and co-workers, who capped the ends of oligo(dihexylfluorene)s and poly(dihexylfluorene)s with Frechet-type dendrons (Figure 7.17C) [73], Annealing experiments coupled with emission studies revealed that G-3 and G-4 dendrons were effective at preventing excimer formation, even when the poly(fluorene) spacer was 50-80 repeat units long. 

Gel formation. We plot in Figure 2 the helix amount versus time (in hours), for quenching and annealing experiments at different temperatures (C=4,7% g cm"3). In Figure 2-a, the time is reported in a linear scale, while in Figure 2-b it is in a logarithmic scale (up to 10 hours). In the first figure, the helix amount seems to tend towards an asymptotic limit, which is temperature dependent, but in the second one one sees clearly that no limit exists, one may suppose, until all the residues would be in a helical conformation (X=1). The transformation is not completed within periods of observation of the order of 10 hours. 

A silane-based CVD reactor suitable for performing high-temperatnre anneals in an Si- rich ambient was used for these experiments [86]. The samples were placed on a SiC-coated graphite susceptor and an RF induction coil used to heat the susceptor to temperatures on the order of 1,600-1,800°C. Silane and argon were the two process gases used, where Ar not only serves as a dilutant gas but also as a carrier gas to transport silane molecules to the crystal surface. All the implant annealing experiments were performed at atmospheric pressure. 

More evidence for enhanced porosity in irradiated PBS films is provided by postexposure annealing experiments. The solubility rate of an irradiated MP20 film which was annealed for 30 minutes at 120 C before dissolution was lower than the solubility rate of the unannealed film. Table IV shows the measured solubility rate loss and the expected solubility rate loss, Sr(IF) — Sr(IP), if all the porosity created during irradiation were removed by annealing. The soluMity rate of the annealed IF-type films are somewhat higher than IP-films of similar M . Thus, the annealing process removes most but not all of the porosity created during irradiation. 

The retention of fission product iodine and xenon by unirradiated and irradiated pyrolytic-carbon-coated (Th,U)C2 fuel particles has been studied in annealing experiments and has been compared with similar studies of the release (or retention) of barium and strontium. The objective was to study the effects of irradiation on the retention of the two types of fission products and to determine the mechanism of release which could account for the observed behaviors. In both unirradiated and irradiated particles, iodine and xenon were found to be retained highly by the impervious isotropic pyrolytic coating which was unaffected by the irradiation. In contrast, the fuel kernel which controls the release of the metallic species is damaged severely by the irradiation, resulting in a marked decrease in its ability to retain the metals. 

Annealing experiments on meteorites and terrestrial feldspars, and studies of separated components from meteorites, suggest that the high and low temperature forms of feldspar have distinctive TL peak temperatures and widths and thus provide a new means of exploring equilibration temperatures and cooling rates. 

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