THE FORWAKD CHARACTERISTIC OF THE PIN DIODE 705 



tween and 1. We see that (30) must be replaced by 



Inllp = Ry" 

 I Ry'^I (93) 



^ / + Ry"^ " 1 + Ry"' 



and (23) must be replaced by 



no = niiln/Intf^" , ^ 



(94) 



Hu, = ni{Ip/Ips) 

 The equation for y is now 



- 1 _ // Y""'"' (y/y.T - i ,05) 



'^ ~ \lj [1 + biy/yjy^Y-'^''-'^^ ^ 



where yj = (h/RY'" and 



/i = hihs/ht-'""-'' (96) 



is a characteristic (particle) current density of the device. We now ob- 

 tain ^Vp from (26) 



^Vp ^ C'{I/h)'-'""'' (97) 



where C is a slowly varying function 



C' = (t/Toc')'" + 1 ^ny ,ggx 



[1 + biy/yjy^Y-'""^' 7-1 



similar to the coefficient in brackets in (41). From (21) and (94) Ave get 



^(Fo + V.) =^ln-^ (99) 



If now 7 '^ 1 we get 



This shows how we must choose a to agree with the low current charac- 

 teristic. On the basis of experience with silicon diodes we would choose 

 a ^' 0.6, which would give 



/SFp - C'(I/hf'' (101) 



riic characteristic current density would be 



I eh ~ 200 X (7p,//o)"'amp/cm' in Si (102) 



