CHEMICAL INTERACTIONS AMONG DEFECTS IN Ge AND Si 613 



would be the analogue of the polyelectrolyte molecule in the aqueous 

 solution. 



An interesting question, in the diffusion of substitutional acceptors, 

 concerns whether the ion or the neutral atom is responsible for diffusion. 

 It is possible that the neutral atom, less securely bonded to the lattice, 

 is the chief agent. This might be determined by changing the ratio of 

 neutral atoms to ions by suitably doping with other donors or acceptors. 



Doping apparently affects the concentration of vacancies which have 

 acceptor properties and therefore the rate of diffusion.'"'' '^^ 



Other interesting effects concerning the distribution of an impurity 

 between two different kinds sites in the lattice^^ are also possible. 



These and many other fascinating fields still require exploration. We 

 hope to investigate some of them in the near future. 



ACKNOWLEDGMENTS 



The authors are greatly indebted to A. J. Pietruszkiewicz, Jr., for as- 

 sistance in carrying out experimental work relating to solubility and 

 diffusion and to J. P. Malta for help with experimental work on Hall 

 effect and an ion-pair relaxation. Thanks are due N. B. Hannay for many 

 helpful comments during the course of the work and during preparation 

 of the manuscript. Thanks are also due Miss M. C. Gray for the evalua- 

 tion of the integrals in Section VII and to F. G. Foster for the photograph 

 of Fig. 8. Finally the authors would like to thank the editors of the 

 Bell System Technical Journal for providing space so that all of the im- 

 portant features of our subject could be treated in one article. 



Appendix A 



THE EFFECT OF ION PAIRING ON SOLUBILITY 



In Section VHI attention was called to the fact that ion pairing should 

 have some effect on lithium solubility but that it would be difficult to 

 achieve conditions under which the effect would be observable. Now, this 

 point will be enlarged upon. Consider an equilibrium like (2.1) except 

 imagine it to take place in germanium with gallium as the immobile ac- 

 ceptor. (This because germanium with gallium has been studied in ion 

 pairing investigations.) 



Li (external) ^ Li"*" + e~ 



+ + 



Ga~ -1- e+ (Al) 



Ti U 



[Li+Ga"] eV 



