Sb segregation in Si and SiGe: effect on the growth of self-organised Ge dots

The segregation and incorporation coefficients of antimony (Sb) in Si1-xGex buried doped layers were investigated simultaneously using specific temper ature sequences. We first showed an exponential kinetic evolution of Sb sur face segregation in Si. In contrast such an evolution could not be observed in Si(1-x)G(x) because of the Sb thermal desorption, at growth temperature s of 550 degreesC. We also showed an increased surface segregation increasi ng with the partial Ge concentration in Si1-xGex alloys, which was explaine d by a decrease of the kinetic barrier for Sb atoms mobility. It was, there fore, possible to determine the growth conditions to obtain a Si1-xGex dope d layer with a controlled incorporation level and a negligible surface segr egation obtained by the thermal desorption of the Sb surface coverage. Fina lly, using Sb surfactant mediated growth, we found Ge dots with lateral siz es: reduced by a factor of 2.8 and density multiplied by a factor of four a s compared to dots directly deposited on Si(001). (C) 2000 Elsevier Science B.V. All rights reserved.