Thermionic emission in silicon at temperatures below 30 K

Experimental results on the injection of carriers into the i region of silicon p-i-n diodes at temperatures below 30 K are described and a simple model is presented to explain the observed I-V characteristics. A range of temperatures is identified in which it is argued that thermionic emission into the i region can be observed unmasked by other effects. The model generalizes the Richardson–Dushman equation to include the effect of impurity bands and a finite transition region between heavily doped and lightly doped regions. As an application, a fast nondestructive means of determining the abruptness of doping profiles is suggested.