Plastic Deformation of Germanium and Silicon

Single crystals of germanium and silicon have been plastically deformed at elevated temperatures. Germanium becomes ductile above 500°C, and silicon requires temperature above 900°C. At temperatures below 600°C, germanium exhibits an induction period at constant load. Deformed germanium, originally $n$-type, remains $n$-type. The resistivity is increased by deforming, and the lifetime of photo-injected carriers is drastically reduced.