998 



THE BELL SYSTEM TECHNICAL JOURNAL, JULY 1957 



indicate any correlation between surface concentration and diffusion 

 constant. 



The variations in diffusion process control have not been observed to 

 effect the production of rectifiers. If better geometry control is necessary, 

 more sophisticated diffusion tochniriues are required. 



VI PULSE PROPERTIES AND RELIABILITY 



Important considerations in all diode applications are the pulse prop- 

 erties and reliability in operation. In this section some problems which 

 are associated with avalanche breakdown are described and the result." 

 related to recent work on surface and body breakdown. 



6.1 Theory 



Several workers" have considered the possibility of a negative resist- 

 ance in the avalanche region for reverse biased junctions in which one 

 side is either intrinsic or so weakly doped that the space charge of the 

 carriers cannot be neglected. A negative resistance might be observed 

 at very high current densities in an N'^tt junction. 



One possible source of a negative resistance would be a large tempera- 

 ture rise due to current concentration at a few points instead of a uni- 



a. 



CD 



5 



0.4 0.5 0.6 0.7 0.6 



Xj [OBSERVED] 

 Xj [CALCULATED] 



0.9 



1.0 



Fig. 13 — Distribution of diffusion depths for diffusion by the open tube depo- 

 sition technique. 



