Dislocation velocities in GeSi bulk alloys

The mechanical strength and dislocation velocities in single crystal Ge_1-xSi_x alloys grown by the Czochralski method were investigated by compressive deformation and by the etch pit technique, respectively. In the temperature range 450 - 700°C and the stress range 3 - 20 MPa, the dislocation velocity in the GeSi alloys with x = 0.004 - 0.053 decreases monotonously with an increase in the Si content, reaching about a quarter of that in Ge at x = 0.053, and can be expressed as a function of the stress and the temperature. The yield stress of the GeSi alloy increases with increasing Si content from x = 0 to 0.4 and is temperature-insensitive at high temperatures, showing that the flow stress of alloy has an athermal component which is absent in elemental or compound semiconductors.