A Novel Model for Boron Diffusion in SiGe Strained Layers Based on a Kinetics Driven Ge-B Pairing Mechanism
A new temperature dependant model for the Ge-B pairing mechanism has been established and implemented in a process simulator. The combination of both lattice strain effects and GeB clustering has been successfully applied to various anneals. The match with experimental SIMS profiles is excellent.
Boron diffusion across silicon–silicon germanium boundaries
Most boron diffusion studies in Si–Ge have been made in regions of uniform germanium content. In this paper diffusion is observed from a boron-doped epitaxial silicon layer across surrounding Si–Ge layers. Pileup of boron in the Si–Ge layers shows that the activity coefficient for boron in Si–Ge is lower than that for pure silicon. A simple pairing model for Si–B interaction fitted the pileup quite well, with the same equilibrium constant applying to both Si0.9Ge0.1 and Si0.97Ge0.03 layers. The effect of this was simply to immobilize a significant fraction of the boron while retaining its acceptor qualities, the ratio of immobile boron to normal substitutional boron being proportional to the germanium content. Quasielectric field effects at the Si–SiGe interface have a strong effect on the results obtained.
D'une application pratique des indices bio-météorologiques
Abstract The purpose of the author is to determine statistically in what part of Switzerland maize could be cultivated with certain chance of rentability. The author gives first the method he used for determining the biometeorological index of four species of maize which were selected by the Swiss agronomical research stations. He has considered two possibilities for the growing period: ( a ) raising-ripening (l'approche globale); ( b ) raising-flowering, flowering-ripening (l'approche fractionee). From the biometeorological index, he calculated retrospectively the ripening time of these four species in the years 1901–1965. Assuming a priori that maize should be harvested before October 15th at the latest, he calculated, for a number of meteorological stations, the relative number of years when such conditions were fulfilled. Dividing the country in regions of similar mesoclimates and sorting these stations per region, it is possible to average the maximum altitude where maize can ripen at least 7, 8, 9 and 10 times within 10 years. Finally, taking into account the exposure and ground slope, he draws maps of the theoretically possible extension area, which maps are more reliable and detailed than the ones derived from actual means.