A new model for impurity diffusion in silicon by a point defect-impurity pair mechanism is described. A pair of coupled, nonlinear, partial differential equations for the silicon self-interstitial and the impurity is derived and solved numerically. The familiar kink and tail of phosphorus and, to a lesser extent, boron diffused profiles arise naturally from the solution. The coupling between defect and impurity becomes smaller at high temperatures and at low impurity concentrations, in agreement with experimental observations. The transient buildup of the defect concentration may have implications for models of rapid thermal processes.

A simplified five-species nonequilibrium kinetic model for phosphorus diffusion in silicon is presented. The resulting system of evolution equations is of a simple reaction-diffusion form with constant diffusivities. Using first-order thermodynamic estimates for reaction rates, the phosphorus profile after a 10 min predeposition shows the expected tail. However, only when the bimolecular generation-recombination rate is significantly increased does a kink-plateau result. This suggests that recombination may be the dominant factor in producing the known nonlinearity.

No abstract

No abstract

2014 La théorie de Landau-Ginzburg dépendante du temps a été généralisée pour inclure un couplage entre le paramètre d'ordre et la densité. Près de la transition, ce couplage donne naissance à une divergence dans les viscosités de volume. Il en résulte un accroissement de l'atténuation du son qui apparaît pour toutes les orientations. Près de la transition, ce couplage donne aussi une contribution à la vitesse. Ces résultats sont en accord avec de récentes expériences. Abstract. 2014 The time dependent Ginzburg-Landau theory of the nematic-smectic A transition is generalized to include coupling of the order parameter to the density. This coupling gives rise to a divergence in the bulk viscosities near the transition, which causes an isotropic anomalous attenuation of sound. The coupling also gives a contribution to the speed of sound near the transition. These results are in agreement with recent experiments.