CHEMICAL INTERACTIONS AMONG DEFECTS IN Ge AND Si 551 



10 



19 



10" 



10" 



5 



10'- 



to'' 



10 



13 



10'' 



10'S 



10 



16 



10 



17 



10 



t& 



to' 



|19 



GALLIUM CONCENTRATION IN CM" 



Fig. 4 — Room temperature isotherm showing the solubility of lithium in 

 germanium as a function of gallium doping, the external phase being an alloy of 

 lithium and germanium. The curve merely shows locus of experimental points. 



precipitation which might normally occur upon cooling a crystal speci- 

 men. An experiment demonstrating this effect is described in Reference 6. 

 Two specimens of germanium, one without added acceptor, and the other 

 containing gallium at an estimated concentration of 1.3 X 10 cm" , 

 were saturated with lithium. Table I compares the changes in lithium 

 content observed in these samples with the passage of time. After 25 

 days no apparent precipitation had occurred in the gallium doped speci- 

 men, while precipitation was almost complete in the other. 



This result suggests a practical scheme for measuring the concentra- 

 tion of lithium along the solidus curve of the lithium-germanium phase 

 diagram, i.e., the solubility of lithium in solid germanium when the ex- 

 ternal phase is also composed of germanium and lithiimi, and probably 

 represents the liquidus phase. This measurement, though desirable, has 

 not been performed before because lithium, diffused into germanium at 

 an elevated temperature, precipitates when the specimen is cooled. 



