An Improved Technique for the Growth of Ultra-Pure Germanium

It has been demonstrated that by utilizing a new method of multiple pulling, it is possible to consistently produce 3 inch diameter germanium crystals with net carrier concentrations in the low 1010/cc range. This method involves two factors which are used to full advantage: 1) the germanium is purified as a result of the normal segregation of impurities, and 2) the usual handling and etching of furnace parts and germanium between successive pulls, as in multiple generation growth, is eliminated. By means of low temperature Hall and axial resistivity profile measurements, we have followed the segregation of both donors and acceptors in various stages of growth. We have observed the normal segregation of impurities and the presence of a continuous impurity background source within the system.