Automated Growth of Si1-xGex Single Crystals with Constant Axial Gradient by Czochralski Technique

This contribution presents the growth of Si1-xGex crystals with constant gradient of composition for X-ray or gamma-ray diffraction optics using automated control of the crystal shape during the growth process. The key idea is to achieve a constant concentration gradient by continuously decreasing the crystal diameter during the main crystal growth phase. For this purpose a concept has been developed for a proper planning of the radius trajectory matching all technological requirements. Si1-xGex single crystals with constant gradients between 0.10 and 0.16 at% cm(-1) have been grown using an automated control system.