DIFFUSED jy-n JUNCTION SILICON RECTIFIERS 



667 



II 



10 



10 



10" 



10 



10" 



10 



2 

 3 

 4 

 5 



6 

 7 



0.4 



O.f 



1.6 



2.0 



y 



2.4 



3.2 3.6 4.0 



Fig. 3. — Error function complement. 



with little recombination. To maintain electrical neutrality, holes are 

 jinjected into the x region from the P+ region. These extra mobile car- 

 riers (both eleictrons and holes) reduce the effective resistance of the tt 

 jlayer and thus decrease the voltage drop across this layer. The higher 

 (he current density, the higher is the injected mobile carrier densities 

 Mid therefore, the lower is the effective resistance. It is for this reason 

 iliat the process is termed conductivity modulation. This effect tends 

 'to make the voltage drop across the tv region almost independent of the 

 current, resistivity, and semiconductor type. 



When the junction is biased in the reverse direction, a normal re- 

 verse characteristic with an avalanche breakdown is expected and ob- 

 served. 



3.3 The forward characteristic of a typical \uiit is plotted semi- 

 logarithmically in Fig. 4. The best fit to the low current data can be 



