Growth and dislocation behavior in GeSi bulk alloys

Bulk crystals of Ge_1-xSi_x alloys in the whole composition range 0<x<1 were grown by the Czochralski technique. Full single crystals were obtained for the alloy composition 0<x<0.15 and 0.9<x<1. The dislocation velocity decreases with increasing Si content in the range 0<x<0.08, while the dislocation velocity first increases and then decreases with increasing Ge content in the range 0.94<x<1. The dislocation velocities were determined as functions of stress and temperature. The stress-strain behavior of the alloys becomes temperature-insensitive at high temperatures. The yield strength of the alloys depends on the composition, proportional to x(1-x) over the whole composition range. Built-in stress fields related to local fluctuation of the alloy composition and the dynamic development of a solute atmosphere around dislocations, seem to suppress the activities of dislocation and bring about alloy strengthening.