CHEMICAL INTERACTIONS AMONG DEFECTS IN Ge AND Si 601 



XII. INVESTIGATION OF ION PAIRING BY ITS EFFECT ON CARRIER MOBILITY 



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

 influence the mobility of holes, because each pair formed, reduces the 

 number of charged impurities by two. Thus, a specimen previously doped 

 with acceptor, might, if sufficient lithium is added, exhibit an increase in 

 hole mobility, even though the addition of lithium implies the addition 

 of more impurities. This effect has been observed in connection with the 

 Hall mobility of holes in germanium. 



Two specimens of germanium were cut from adjacent positions in a 

 single crystal doped with gallium to the level 3 X 10^^ cm~l One of these 

 iwas saturated with lithium through application of the same procedure 



TEMPERATURE IN °C 

 200 100 



25 



r 



1.4 



1.6 



1.8 2.0 



2.2 2.4 2.6 2.S 3.0 3.2 



Y X 10^ 



^3.4 



Fig. 24 — Plot of diffusivity of lithium in undoped germanium as a function 

 of temperature — also showing points for apparent diffusivities of lithium in 

 variously doped specimens. 



