Negative resistance induced by avalanche injection in bulk semiconductors

The negative resistance induced by space-charge effects in bulk semiconductor devices subjected to avalanche multiplication has been studied to clarify the physics of this phenomenon and the validity of the assumptions made by other authors. On the basis of the numerical results, an analytical model is proposed, using the regional approximation to evaluate the field along the device and the J-V characteristic. Both the numerical and the analytical results show the role played by the injection of electrons from the cathode and the velocity saturation for the onset of negative resistance, as well as the role of hole injection from the multiplication region near the anode into the bulk for the subsequent voltage lowering. Experimental results are in good agreement with the analytical model in a wide range of device parameters.