The Use of Semiconductors Doped with Isoelectronic Traps in Scintillation Counting

The use of semiconductors as scintillation phosphors is discussed. Donoracceptor pair recombination is efficient but it is often slow. The presence of free carriers from high concentrations of electrically active defects causes concentration quenching probably by means of an Auger effect. One is led therefore to consider the use of semiconductors doped with "isoelectronic traps". Experiments are reported for CdS doped with tellurium and ZnTe doped with oxygen. Promising preliminary results have been obtained. For CdS:Te at room temperature using 5 MeV α particles pulse heights have been recorded 7 times greater than those provided by the scintillator Pilot B, and with a rise time of 300 ns. At 100°K the results are even better. An excellent linearity of response at 100°K was found for particles with energies between 7 keV and 5.2 MeV. In addition to detecting α, ß and γ particles, CdS:Te is also a good potential detector of thermal neutrons.