CHEMICAL INTERACTIONS AMONG DEFECTS IN Ge AND Si 629 



Q 



Z 



o 



10' 



10'^ (0'^ (0'° (0' 



CONCENTRATION OF IONIZED IMPURITIES IN CM"^ 



(0" 



Fig. 30 — Plot of hole-drift mobility in germanium as a function of ionized 

 impurity concentration after Prince. 



The numerical evaluation has been performed for a range of Nd^ in 

 both the pairing and non-pairing cases. In this manner it has been pos- 

 sible to evaluate the "correction factor" t^ defined by the following equa- 

 tion 



/ niv) erfc V dv = t?M«> / erfc v 

 Jq Jo 



= t?Moc(0.563) 



dv 



(E12) 



where /i^ is the mobility in the presence of A^^ scatterers. Fig. 22 contains 

 plots (for germanium) of i}(ND°) versus A^d" for both the pairing and non- 

 pairing cases. It is seen that t> is never much different from unity. 

 Equation (E5) can now be written as 



2 = a;Mo(A^^ - ND°)d/2 + COM [i .l2St}N ^W D]\/t (E13) 



Defining 



2o = coMoCN^ - ^z>°)d/2 



^00 — X 



(E14) 

 (E15) 



it is obvious that So is the conductance before any donor has diffused 



