Experimental verification of a new approach to the analysis of the quasineutral carrier transport in semiconductors and semiconductor structures

According to the recently suggested new approach to the description of the quasineutral transport in semiconductors and semiconductor devices, the current–voltage characteristics of the p+–p–n+ and p+–n–n+ structures fundamentally differ at large W/L ratios and high current densitiesj (W is the base width of a semiconductor structure, and L is the ambipolar diffusion length). In the p+–p–n+ structures, the differential resistance Rd must steadily decrease with increasing j at high injection levels for any W/L ratio. In the p+–n–n+ structures, it would be expected that the 'classical' decrease in Rd with increasing j should give a way to an increase in Rd when j approaches from below a critical value jcrn. Then, at j > jcrn, the decrease in Rd with increasing j must be resumed. These predictions were experimentally verified on Si p+–p–n+ and p+–n–n+ diodes. The W/L ratio in these structures was varied by irradiation with fast (1 MeV) electrons or gamma photons from a Co60 source. The results obtained fully agree with the predictions of the new approach to the analysis of the quasineutral carrier transport in semiconductors and semiconductor structures.