Performance degradation of Si(Li) detectors with a working area of 20–60 cm2

Abstract

The objective of this work is to investigate the degradation of the characteristics of silicon-lithium detectors under conditions of diffusion decompensation of local accumulations of an acceptor impurity. The change of the capacitance versus voltage and the noise versus voltage characteristics of a 60 square centimeter detector were measured over a 2-year period. The increase in the capacitance, noise, and total depletion voltage substantially degraded the spectrometric and counting characteristics of the detector. Degradation was accelerated by the decomposition of a supersaturated solid solution of lithium in silicon. However, the initial characteristics of the detector can be restored by instituting equalizing drift and storing the detector at low temperature or with reverse bias. Degradation processes can also be slowed by using silicon crystals with a high oxygen content. 4 refs., 4 figs.