Physical review volume 05, number january 15, 1957

ACKNOWLEDGMENTS
The authors would like to thank J. A. Ditzenberger and J. P. Maita for experimental assistance and N. B. Hannay and Howard Reiss for helpful comments on this work.

PHYSICAL REVIEW


VOLUME 105, NUMBER 2


JANUARY 15, 19 5 7

Formation of Ion Pairs and Triplets between Lithium and Zinc in Germanium
F. J. Morin and Howard Reiss
Bell Telephone Laboratories, Murray Hill, New Jersey
(Received October 3. 1956)
This paper is a study of ion pairs and triplets formed between zinc and lithium dissolved in single crystal germanium. As in earlier work on ion pairs involving simpler acceptors, the effects of ion complexes on Hall mobility, and impurity energy levels have been investigated. Relaxation-time experiments have also been performed. The theoretical analysis of the results is in complete accord with the idea that zinc provides two energy levels for electrons in the forbidden gap.

1. 
   INTRODUCTION
   

HE formation of ion pairs in germanium and silicon has been discussed in detail in a recent paper.¹⁸ The occurrence of pairs involving the donor lithium and singly charged acceptors such as gallium, aluminum, indium, and boron has been demonstrated experimentally. With the exception of its influence on the diffusivity of lithium, zinc, as an acceptor, was not investigated in any of these experiments. Nevertheless zinc is an especially interesting acceptor since, according to Tyler and Woodbury,¹⁹ it is doubly charged when ionized, possessing energy levels at 0.03 and 0.09 ev above the valence band. This fact is supported by the diffusion data, mentioned above, which show zinc to be orders of magnitude more efficient than the other acceptors in reducing the diffusivity of lithium.
In this article the further investigation of zinc will be described and it will be seen that all measured phe­nomena associated with ionic interaction are in accord with the existence of two energy levels. Along with pairing, triplet formation is possible when doubly charged ions are involved. This subject will be discussed in the following section.

2.