SINGLE CRYSTAL BY ZONE LEVELING 



659 



300 

 200 



100 

 600 

 400 



200 



100 

 5 80 

 Z 60 

 tu 40 

 I- 400 



LU 

 LL 



_l 



200 



< 



liJ 100 

 < 80 



60 

 40 



20 



10 



in 



Q 



z 

 o 

 o 



LU 

 10 



o 



cc 

 u 



2 3 4 5 



DISTANCE FROM SEED IN INCHES 



Fig. 12 — Average minority carrier lifetime plotted against distance from seed 

 for 2-8 ohm cm crystals grown with 12", 5" and no after-heaters. 



for clearly attributable causes such as power or equipment failure. There 

 were few cases of lineage in the short after-heater and virtually none in 

 the full after-heater, while lineage is not uncommon in ingots grown with 

 no after-heater. 



(3) Micro Perfectio7i 



Table II summarizes the etch pit density, e, measurement results. In 

 general, it can be seen that with the after-heater one can expect etch 

 pit counts of the order of 1,500 pits per cm- which is lower than results 

 without an after-heater by about an order of magnitude (and lower than 



Table II — Average Etch Pit Densities, e 



