THEORY OF THE SWEPT INTRINSIC STRUCTURE 



1253 



quently recombination can be neglected over parts of the intrinsic 

 region but not near the center, where the field is a minimum and the car- 

 rier concentration a maximum. Then (3.4) will represent the field dis- 

 tribution over that part of the region where recombination is unimpor- 

 tant. The correct solution will join onto the cubic as we move away 

 fi'cjm the center of the intrinsic region, which will no longer be at the 

 x — point on the cubic. In Section IV we solve the ecjuations for the 

 recombination region and show how the solution approaches the cubic. 

 ^\e ^\•ill show that, as A increases, the distance from the center of the 

 intrinsic region to the x = point on the cubic also increases. The 

 value A = % corresponds to an infinitely long intrinsic region. For a 

 larger A there exists no exact solution that could join onto the cubic 

 as recombination becomes negligible. In Figs. 3 and 4 the .4 = § curves 

 join onto recombination solutions at values of E which are too low to 

 show. 



0.15 

 14 

 0.13 

 0.12 

 0.11 

 0.10 

 0.09 

 0.08 

 0.07 

 0.06 

 0.05 

 0.04 

 0.03 

 0.02 

 0.01 



0.02 



0.04 , 0.06 



x/2Ll 



0.08 



0.10 



Fig. 2 — Field Distributions for L = 0.2Li 



