FLOW OF ELECTRONS AND HOLES IN GERMANIUM 605 



obtained by comparing the first terms of the series in 7 with the func- 

 tions of P which result from evaluating the Maclaurin's series for 7 

 small. 



5 . 4 Symbols for Quantities 



a = t/tv , constant in recombination function. 



aj = coefficients in the Maclaurin's expansion of G in powers of P; j an 



integer. 

 Aj = coefficients in the expansion of G in powers of y-jj an integer. 

 A~ = concentration of ionized acceptors. 

 Ao" = thermal-equilibrium concentration of ionized acceptors. 

 b = ratio of electron mobility to hole mobility. 

 C = I/Io , reduced total current density. 

 Ce = reduced emitter current. 



C~ = reduced total current to the origin from the left. 

 C+ = reduced total current from the origin to the right. 

 C„ ^ —I„/Io , reduced electron flow density. 

 Cp = Ip/Io , reduced hole flow density. 

 7 ^I/C. 



T = €/47rcror, reduced time for the dielectric relaxation of charge. 

 D = total donor concentration. 

 ZH" = concentration of ionized donors. 



Do = thermal-equilibrium concentration of ionized donors. 

 Dn = kTun/e, diffusion constant for electrons. 

 Dp ^ kTiXp/e, diffusion constant for holes. 

 e = magnitude of the electronic charge. 

 E = electrostatic field. 

 Ea = applied or asymptotic field. 

 Eo = kT/eLp , characteristic field, 

 e = dielectric constant. 



/ = fraction of total current carried by holes. 

 ft = fraction of total current carried by holes at an emitter. 

 /"~ = fraction of total current carried by holes at a source, to the left. 

 /+ = fraction of total current carried by holes at a source, to the right. 

 F = E/Eo , reduced electrostatic field. 



go = thermal rate of generation of hole-electron pairs, per unit volume. 

 G = dP/dX, reduced concentration gradient. 

 G° = value of G for X = 0. 



G~ = limiting value of G at a source, approached from the left. 

 G^ = limiting value of G at a source, approached from the right. 

 H = probability of thermal ionization of an unionized donor, per unit 



time. 



