Mechanical strength of GeSi solid solution

The mechanical strength of Ge_1-xSi_x crystals with x ranging from 0 to 0.4 grown by the Czochralski method was investigated as functions of the composition and temperature by compressive deformation. The stress-strain curve of the GeSi alloys with a yield point phenomenon is similar to that of Ge and Si in the temperature range lower than about 600°C. However, the yield stress of the alloys is temperature-insensitive at high temperatures and increases with increasing Si content in the range investigated. The composition dependence of the yield stress can be expressed by an x(1 - x) relation. The flow stress of GeSi crystals has an athermal component that is absent in Ge and Si and gives rise to solution hardening. The hardening mechanism in alloy semiconductors is discussed.