606 BELL SYSTEM TECHNICAL JOURNAL 



I = total current density. 



/„ = current density of electrons, 



/o = aEa , characteristic current. 



Ip = current density of holes. 



J = - I, total carrier flow density. 

 e 



Jn = In, electron flow density. 



e 



Jp = - Ip , hole flow density. 

 e 



k = Boltzmann's constant. 



K = probability per unit time of electron capture by an ionized donor, 



per unit electron concentration. 

 Ld ^ (kTe/HirHie-) , characteristic length associated with space charge 



in the steady state. 

 Lp = {kTixr/e), diffusion length for holes for time t. 



M = 1 + 



Mo= 1 + 



b 

 b-\- 1 



b 



fi = Up = mobility for holes. 



Hn = mobility for electrons. 



n = concentration of electrons. 



Hi = thermal-equilibrium concentration of electrons (or holes) in the 

 intrinsic semiconductor. 



«o = thermal-equilibrium concentration of electrons. 



Hg = saturation concentration excess of electrons, corresponding to com- 

 plete ionization of donors. 



A^ = n/{no — po), reduced electron concentration for an «-type semi- 

 conductor. 



P = concentration of holes. 



po = thermal-equilibrium concentration of holes. 



P = p/(no — po), reduced hole concentration for an w-type semiconductor. 



AP = {p — po)/{no — po), reduced concentration of added holes. 



Pq = po/(no — po), reduced hole concentration at thermal equilibrium. 



po - value of P for X = 0. 



Q = t/tp , lifetime ratio. 



R = general recombination function, equal to 1 + aP/{l + Po) for 

 mass-action and constant-mean-lifetime mechanisms combined. 



p = volume resistivity in ohm cm. 



s = differential transport velocity. 



S = s/(Dp/t) , reduced differential transport velocity. 



