Semiconductor detectors for use in high radiation damage environments — Semi-insulating GaAs or silicon?

There is a need for high-resolution solid-state tracking detectors for use in high radiation, long-life experiments where there can be considerable degradation in their electrical performance. A discussion is given of the relative merits of GaAs and silicon in the context of the underlying semiconductor device physics. Although the relative performance, in terms of the charge collection efficiency at the end of life, depends on the details of the type and amount of damage produced, it is shown that the qualitative electrical behaviour is predictable using relaxation semiconductor theory. Experimentally, diodes of semi-insulating GaAs and irradiated silicon have similar qualitative performance. Suggestions are given as to how the performance may be improved.