VGF growth of germanium single crystals without crucible contact

Exptl. results on the vertical gradient freeze growth of germanium single crystals without crucible contact are presented. Two different approaches to establish a stable pressure difference necessary for avoiding the contact between crystal and crucible on solidification are described. Germanium crystals with a diam. of up to 3 in were grown almost without contact to the crucible wall. The effect of detachment is discussed with respect to the microscopical surface roughness and dislocation d. of the grown crystals. In comparison to conventionally grown ref. crystals the structural perfection of the detached-grown crystals is found to be much higher which can be attributed to the reduced thermal and thermomech. stress in growth without wall contact.