An investigation of the manufacture of germanium single-crystal ingots by the levelling process

The factors influencing the crystal perfection and resistivity spread of ingots made by levelling have been examined theoretically and an attempt has been made to apply the conclusions drawn to the design of levelling equipment and the choice of process variables. The results have indicated that a low thermal gradient at the growing solid/liquid interface and high growth velocity are desirable from the point of view of crystal quality. However, the existence of such a low thermal gradient has an adverse influence on cross-sectional resistivity variations as a result, it is thought, of a micro-refining process. It is concluded that improved crystal quality with good control of crosssectional resistivity distribution can only be achieved by improved temperature control.