Thermally Induced Acceptors in Germanium

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Abstract
When germanium is rapidly quenched from high temperature, acceptor centers are formed uniformly throughout the crystal. These centers have an energy of formation of about 2 ev. Each center is thought to contribute two acceptors, one near the valence band and one near the center of the gap. Experiments are described which indicate that these centers are either vacant lattice sites or a heretofore unidentified chemical impurity with radius smaller than that of germanium. Annealing has been studied in the temperature range 250°C-450°C. The annealing process is shown to depend markedly on both the density of dislocations and the concentration of copper. It has not been possible to ascribe a consistent physical model to conform with the observed characteristics of the annealing process.