INFLUENCE OF ACCUMULATION OF THE MINORITY-CARRIERS IN A P+-TYPE LAYER ON THE RECOVERY OF THE VOLTAGE ACROSS A P+-N JUNCTION

A study was made of the influence of accumulation of the minority carriers in a heavily doped p+-type layer of a p+-n-n+ diode on the process of recovery of the voltage across the diode when the direction of the current flowing through the diode was reversed. Experiments carried out on diodes with different gradients dn/dx of the dopant concentration in the p-n junction showed that the accumulation of carriers reduced significantly the rates of rise of the voltage across the diode during the stage when carriers were removed from it. A numerical calculation yielded results in good agreement with the experimental data when only one parameter (the injection efficiency of the p+-n junction) was varied. The value of this efficiency ranged from 1 to 0.26 for diodes with different values of dn/dx. In particular, when dn/dx was reduced from 8 X 10(8) to 1.2 X 10(8) cm -4, the injection efficiency decreased from 0.5 to 0.26.