MAGNETIC-FIELD ELIMINATION OF CONVECTIVE INTERFERENCE WITH SEGREGATION DURING VERTICAL-BRIDGMAN GROWTH OF DOPED SEMICONDUCTORS

Elimination of convective interference with segregation through application of magnetic fields during growth of doped semiconductors in a constant axial thermal gradient environment is studied. Results of numerical simulation of governing equations are used to generate the scaling laws controlling the process. A general relationship for the field strenghts required to achieve diffusion controlled growth of doped semiconductors is developed. Modelling predictions compare very well with experimental results on magnetic growth of Ge. The present model in conjunction with the maximum field strenghts currently available is used to establish the effectiveness limit of applied magnetic fields for growth of compositionally uniform Ge, GaAs, and CdTe crystals. The effectiveness limits of magnetic and micro-gravity growth are compared. It is shown that at gravity levels of 10-4 of the earth gravity, the limitations of the two approaches in terms of materials and charge sizes are similar. At gravity levels of 10-6 of the earth, the diameter of charges that can be grown at diffusion controlled limit is larger than those that can be currently grown on earth through application of magnetic fields. © 1990.