118 THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1952 









-1.0 -0.5 0.5 1.0 -1.0 -0.5' -0.5 









-200 -150-100 -50 



(a) (b) (c) (d) 



Fig. 8 — Effect of impurity content, (a) hyper-purit}' silicon, (b) liigh-j)urity 

 silicon, (c) hyper-purity silicon plus 0.02 per cent boron, (d) high-puritj- silicon 

 plus 0.1 per cent boron. 



