The Semiconductor Fast-Neutron Dosimeter-Its Characteristics and Applications

The characteristics and most recent results with a semiconductor fast-neutron dosimeter are dTscribed. This device is a wide-base silicon n+ - p - p+ junction whose forward resistance is controlled by the density of injected charge carriers in the base region. The injected carrier density profile is a function of the carrier diffusion length. Upon neutron bombardment, the diffusion length is decreased, which results in a decrease in injected carrier density within the base region and thus an increase in the forward resistance of the device. A sensitivity range from 1010 nvt to > 1014 nvt is presently attainable. The accuracy of readout ranges from ± 50 per cent at 1010 nvt to ± 5 per cent at 1011 nvt and continues to improve at higher integrated fluxes. The effect of base width, forward current level, material properties, and processing parameters on the sensitivity and uniformity of device characteristics are discussed. The current-voltage behavior of the device is shown to correspond to a model by Rose(l) for diffusion-dominated double injection in semiconductors. The small size and ruggedness of the dosimeter and the simplicity of readout make it particularly suited for radiation-effects experimentation, accident dosimetry, and biological dosimetry.