| In Part I of this thesis, a technique of floating shaper with shaper temperature control has been developed to control the crystal cross-section. Two different types of floating shapers, which are either nonwetted or wetted by the melt, have been designed. Sn and NaNO{dollar}sb3{dollar} single crystals have been grown with excellent control over the cross-sectional shape and size using this technique.; In Part II of this thesis, two techniques, i.e., Floating-crucible technique and Elongated-crucible technique, have been developed to control axial dopant segregation. In the Floating-crucible technique, the floating device is unique in that it has a very long melt passageway between the growth zone and the bulk melt to suppress dopant back diffusion. In Elongated-crucible technique, the conventional Czochralski process has been modified to allow melt replenishing, by extending the crucible well below the heater and lowering the heater during crystal growth. Two model materials, i.e., Pb-doped Sn and Li-doped NaNO{dollar}sb3{dollar}, were selected for crystal growth. Chemical analysis of the resultant crystals confirmed that a very uniform dopant distribution was indeed reached in the crystals.; In Part III of this thesis, the segregation control techniques described in Part II were applied to Czochralski pulling of the single crystals of a semiconductor material InSb. Cd-doped InSb single crystals were grown and the Cd concentrations were very uniform in these crystals. It appears that the application of these two segregation control methods to InSb works very well. |
