Anomalous transport of Sb in laser irradiated Ge

Excimer laser annealing is shown to be very promising to promote Sb incorporation in Ge upto concentrations as high as 11021 at./cm3. However, we demonstrate that when Ge is melted bylaser irradiation, a high excess of vacancies is generated in the molten region. These vacanciesinduce Sb electrical deactivation at the melt depth through the formation of Sbm-Vn complexes thatact as a sink for further Sb atoms, even leading Sb to back-diffuse towards the surface, against theconcentration gradient. These results are fundamental for the realization of new generationGe-based micro and optoelectronic devices.