804 



THE BELL SYSTEM TECHNICAL JOURNAL, JULY 1954 



3. MINORITY CARRIER DELAY DIODE 



As a first example we shall consider the behavior of the device shown 

 in Fig. 3.1. We have chosen a p-n-p structure rather than an n-p-n so as 

 to deal with positively charged carriers and thus avoid numerous minus 

 signs in the ecjuations. In this figure we have used capital letters P and A^ 

 to designate specific regions, reserving the small letters to indicate carrier 

 densities and conductivity types. 



Several features that simplify the theoretical treatment should be 

 noted : 



(a) The PiN junction is 100-fold more heavily doped on the Pi-side. 



(b) The doping in the layer N varies exponentially ^^•ith distance by 

 a factor of 10 across the layer. 





—*\ 



10'9 

 10'8 

 10'^ - 

 10'6 - 

 ID'S 



10'3 

 I0'9 

 I0'6 

 I0'7 

 1016 

 lO'S 



Fig. 3.1 — Constitution of minority carrier delay diode. 



