Static characteristic of long silicon dosimetric diode

A one-dimensional model is designed of a long silicon diode of the P+NN+ type for fast neutrons dosimetry in which an uneven injection is assumed at the two junctions (asymmetric model). An analytical relation is derived for local distribution of the concentration of excessive charge carriers, a relation for the source of the voltage along the diode base for the case of constant carrier life-time and from it is derived the static current-voltage characteristic. Also discussed is the case of significant variation of the carrier life-time with the local concentration of carriers in the base as given by the Shockley-Read-Hall recombination model. The calculation is made of the course of voltage along the axis of the long diode during forward current flow. The possibility was tested of the experimental determination of the life-time of excess carriers in the diode base using derived relations. The relations may be used for the design of sensitive dosimetric diodes. (A.K.)