Lattice diffusion and surface segregation of B during growth of SiGe heterostructures by molecular beam epitaxy: Effect of Ge concentration and biaxial stress
2004 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 96, no 6, 3158-3163 p.Article in journal (Refereed) Published
Si1-xGex/Si1-yGey/Si(100) heterostructures grown by molecular beam epitaxy were used in order to study B surface segregation during growth and B lattice diffusion. Ge concentration and stress effects were separated. Analysis of B segregation during growth shows that (i) for layers in epitaxy on (100)Si, B segregation decreases with increasing Ge concentration, i.e., with increased compressive stress; (ii) for unstressed layers, B segregation increases with Ge concentration; (iii) at constant Ge concentration, B segregation increases for layers in tension and decreases for layers in compression. The contrasting behaviors observed as a function of Ge concentration in compressively stressed and unstressed layers can be explained by an increase of the equilibrium segregation driving force induced by Ge additions and an increase of near-surface diffusion in compressively stressed layers. Analysis of lattice diffusion shows that (i) in unstressed layers, B lattice diffusion coefficient decreases with increasing Ge concentration; (ii) at constant Ge concentration, the diffusion coefficient of B decreases with compressive biaxial stress and increases with tensile biaxial stress; (iii) the volume of activation of B diffusion [DeltaV=-kT(d ln D/dP)] is positive for biaxial stress while it is negative in the case of hydrostatic pressure. This confirms that under a biaxial stress the activation volume is reduced to the relaxation volume.
Place, publisher, year, edition, pages
2004. Vol. 96, no 6, 3158-3163 p.
Boron, Compressive stress, Concentration (process), Crystal growth, Crystal lattices, Diffusion in solids, Germanium, Heterojunctions, Hydrostatic pressure, Molecular beam epitaxy, Segregation (metallography), Surface properties, Tensile testing
IdentifiersURN: urn:nbn:se:kth:diva-40573DOI: 10.1063/1.1781767ISI: 000223720000016ScopusID: 2-s2.0-4944229207OAI: oai:DiVA.org:kth-40573DiVA: diva2:441526
QC 201109162011-09-162011-09-162011-11-15Bibliographically approved