CHEMICAL INTERACTIONS AMONG DEFECTS IN Ge AND Si 561 



return below) to hold the lithium atom, the solubility of lithium will be 

 determined principally by the density of boron atoms. At low tempera- 

 tures, \-a(*an('ies are reabsorbed and the lithium atoms return to their 

 interstitial positions, at quenched-in densities corresponding to the tem- 

 peratures of equilibration. However, boron acceptors now appear to be 

 compensated since interstitial lithium behaves as a donor. This renders 

 it feasible to measure the concentration of lithium by the determination 

 of resistivity. 



The overall reaction may be written in the form 



The original vertical equilibrium involving holes and electrons loses its 

 significance at high temperatures, and the new vertical reaction becomes 

 important, for both D and e~ appear in increased concentrations. In this 

 way a certain amount of symmetry, insofar as temperature is concerned, 

 is introduced into the problem, i.e., as one equilibrium ceases to dominate 



SL SL SL SL SL SL 



v\/ \/\. 



B Sl B SL 



• • \ ::! / \ • 



SL LL"^ □ SL SL LL ^SL 



. . / -e \ . . 



SL SL SL SL 



SL St SL SL SL 



Fig. 11- — Schematic diagram illustrating the reaction in (5.1). The square 

 nqjresents the center of a vacancj^ and the dots, electrons left unpaired by the oc- 

 currence of the vacancy. 



