980 THE BELL SYSTEM TECHNICAL JOURNAL, JULY 1957 



Table I — Values of G and Space Charge Generated 



Current at 300° K for Various Values 



OF the Trapping Level Vr 



T = 300° K Eg = l.OSeF np = 3 X 10'° cur^ 



r„o = 1.2 X 10-« sec Tpo = 0.4 X 10-« sec 



rent by the individual trapping centers given by IscdooiVr)f(T, Vr), where 

 hcsooiVr) is the current at 300° K due to generation at recombmation 

 centers located at the level Vr , and/(T, T^) is the temperature variation 

 of the generation rate. Thus, the total reverse current is given by 



= lomgiT) + Z^.cm{Vr)KT, Vr), 



(2-10) 



where the summation is over all recombination levels. The relative cur- 

 rents at 300° K are given in Table I. The greatest contribution at 300° K 

 is due to the level nearest the center of the forbidden band. As the tem- 

 perature increases, all the terms under the summation sign approach each 

 other. Before a second recombination level contributes significantly to 

 the reverse current, however, the saturation current will ha"\'e become 

 the most important component. 



2.2 Experimental Results 



To evaluate the theory for the reverse currents in silicon N^P junctions, 

 careful measurements were made on five typical units for the reverse 

 current-voltage characteristics at various temperatures from 300° K 

 to 435° K. The curves were taken with a X-Y recorder. The voltage 

 ranged from to 200 volts so that multiplication effects were completely 

 negligible. 



From the recorded data, curves of Ir versus 1,000/T° K were plotted 

 for V = —10, —40, and —160 volts. The set of curves for diode No. 3 



