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Silicon Carbide (SiC) has a high thermal stability and for most elements temperatures in excess of 2000 degreesC are anticipated to reach reasonable diffusivities (greater than or equal to 10(-13) cm(2)/s). We demonstrate, however, that light elements, like hydrogen and lithium, exhibit a considerable mobility already at less than or equal to 400 degreesC, Technologically, the principal interest in these light elements arises because of their ability to electrically passivate shallow acceptors and donors as well as deep level defects in common semiconductors (SiC, Si, GaAs). Indeed, for both hydrogen and lithium the diffusion kinetics is shown to be strongly affected by trapping and de-trapping at boron impurities in the SiC layers. Evidence is also provided that hydrogen migrates as a positively charged ion in p-type SiC. Furthermore, similar to that in crystalline silicon, transient enhanced diffusion of ion-implanted boron is observed in SiC. The initial boron diffusivity during postimplant annealing at 1600 degreesC is enhanced by more than two orders of magnitude compared to equilibrium conditions. For Silicon Germanium (SiGe) diffusion of the n-type dopants Sb and P is studied. Comparing results from strained and relaxed SiGe layers annealed under inert and oxidizing conditions it is unambiguously shown that the diffusion of Sb is almost exclusively mediated by vacancies. On the other hand, P diffusion is predominantly assisted by Si self-interstitials and in this case compositional and strain effects in the SiGe layers are competing., 5th International Conference on Diffusion in Materials, PARIS, FRANCE, JUL 17-21, 2000 NR 20140805

Phosphorus diffusion in a biaxially compressed Si0.87Ge0.13 film has been investigated in the temperature range of 810-900 °C. A significant enhancement of the P diffusion in the biaxially compressed Si0.87Ge0.13 in comparison with P diffusion in Si is observed. Injection of Si self-interstitials (I) during oxidation of a Si-cap in Si/Si0.87Ge0.13/Si heterostructures is used to characterize the atomic mechanism of P diffusion in Si0.87Ge0.13. It is found that the upper limit of the interstitial fraction of the P diffusion in Si0.87Ge0.13 is 0.87 of that in Si. A comparison between B and P diffusivities in SiGe supports the hypothesis of the pairing-controlled mechanism for the diffusion of B in SiGe., References: Harame, D.L., Comfort, J.H., Cressler, J.D., Crabbé, E.F., Sun, J.Y.-C., Meyerson, B.S., Tice, T., (1995) IEEE Trans.ED, 42, p. 455; Cowern, N.E.B., Zalm, P.C., Gravesteijn, D.J., De Boer, W.B., (1994) Phys.Rev.Lett., 72, p. 2585; Kuo, P., Hoyt, J.L., Gibbson, J.F., Turner, J.E., Lefforge, D., (1995) Appl.Phys.Lett., 66, p. 580; KringhÞj, P., Nylandsted Larsen, A., Shirayev, S.Yu., (1996) Phys.Rev.Lett, 76, p. 3372; Kuznetsov, A.Yu., Cardenas, J., Svensson, B.G., Lundsgaard Hansen, J., Nylandsted Larsen, A., (1999) Phys. Rev. B., 59, p. 7274; Hu, S.M., Ahlgren, D.C., Ronsheim, P.A., Chu, J.O., (1991) Phys.Rev.Lett., 67, p. 1450; Aziz, M.J., (1997) Appl. Phys. Lett., 70, p. 2810; Kuznetsov, A.Yu., Cardenas, J., Grahn, J., Svensson, B.G., Lundsgaard Hansen, J., Nylandsted Larsen, A., (1998) Phys. Rev. B., 58, pp. R13355; Kuo, P., Hoyt, J.L., Gibbson, J.F., Turner, J.E., Lefforge, D., (1995) Appl.Phys.Lett., 67, p. 706; Kuo, P., Hoyt, J.L., Gibbson, J.F., Turner, J.E., Lefforge, D., (1995) Mat.Res.Soc.Symp.Proc., 379, p. 373; Fahey, P.M., Griffin, P.B., Plummér, J.D., (1989) Rev.Mod.Phys., 61, p. 289; Hu, S.M., (1974) J.Appl.Phys., 45, p. 1567; Dunlap Jr., W.C., (1954) Phys.Rev., 94, p. 1531; Zhao, Y., Aziz, M.J., Gossmann, H.-J., Mitha, S., Schiferl, D., (1999) Appl.Phys.Lett., 74, p. 31 NR 20140805

6H and 4H polytype silicon carbide (SiC) layers have been grown on ground and under microgravity conditions by liquid phase epitaxy (LPE) from a solution of SiC in Si-Se solvent at 1750 degrees C. The effects of gravity on the growth parameters and material characteristiques have been studied. The growth rate, Sc incorporation, and the structural defects are modified in reduced gravity conditions, while the polytype reproduction of the substrate is not affected. The results obtained are intriguing as to further experiments providing objects for carrier lifetime measurements., NR 20140805