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A phase change memory (PCM) utilizes resistivity changes accompanying fast transitions from an amorphous to a crystalline phase (SET) and vice versa (RESET). An investigation was made on the SET characteristics of PCM cells with Ge-doped SbTe (Ge‐ST) materials of two different Sb:Te ratios (4.53 and 2.08). For the material of higher Sb:Te (4.53), a SET operation was completed within several tens of nanoseconds via nucleation-free crystallization whereas the material of lower Sb:Te (2.08) rendered a slower SET operation requiring several hundred nanoseconds for a nucleation-mediated crystallization. From measurements of nucleation and growth kinetics via laser-induced crystallization, the observed SET characteristics of the former case were found to derive from a growth time about 10 3 times shorter than the nucleation time and those of the latter from a much shorter nucleation time as well as a longer growth time than in the former case. The measured nucleation kinetics of the lower Sb:Te (2.08) material is unexpected from the existing data, which has led us to advance an interesting finding that there occurs a trend-reversing change in the nucleation kinetics of the Ge-ST materials around the eutectic composition (Sb:Te ∼2.6); nucleation is accelerated with the increase in the Sb:Te ratio above Sb:Te of 2.6, but with a decrease in the Sb:Te ratio below it.

This work reports on the preparation of Cr-doped TiO2 (Cr–TiO2) and its utilization in the photoanode of a dye-sensitized solar cell (DSSC). Pure TiO2 and 10% Cr–TiO2 sols were individually obtained viahydrolysis followed by a hydrothermal process at 250 °C for 12 h. The TiO2 sol was first coated on a fluorine-doped tin oxide (FTO) substrate using a polymer binder and sintered at 500 °C for 30 min. The Cr–TiO2 sol was then deposited on the TiO2 layer through the same procedure, thus forming two different layers on the substrate. We found that the photovoltaic efficiency was improved by ca. 18.3% when the double layer was adopted as the photoanode of a DSSC instead of only the TiO2 layer. We assume that this improvement was caused by the repression of electron recombination occurring in the double layer. Further characterizations were carried out to clarify the function of the double layer.

Nous signalons la similitude morphologique et chetotaxique de deux lots de cercaires provenant de Mollusques naturellement infestes recoltes respectivement en Asie et en Afrique. Le premier lot est determine, il s’agit de Clonorchis sinensis ; le second lot est indetermine mais sa presence en Afrique suggere l’introduction de Clonorchis dans ce continent.