High Purity Germanium - Low Temperature Hall Analyses

We present below a synopsis of results of low temperature (to ~7° K) Hall measurements on 58 samples of high purity germanium obtained from six laboratories in the U.S., Canada, and Europe. The measurements show the presence of deep (Cu) and shallow level (Group III and V) chemical impurities as well as deep energy levels associated with complex vacancy and/or oxide defects. In general, we have found that high purity germanium tends to be rather well compensated, i.e., the individua acceptor or donor concentrations are typically 3 to 10 times that of the net carrier concentration at 77° K. The results show that as far as chemical impurities are concerned, Cu contamination is generally a problem at those laboratories using resistance-heated pullers. Shallow level impurity problems seem to be associated with Al most frequently, with some boron contamination observed. The presence of defect-related deep levels has also been observed.