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Diamond has the highest radiation-damage level among radiation-detector semiconductor materials. Besides, low carbon
nucleus charge, Z=6, provides tissue equivalence of diamond detectors. This made it possible to create unique diamondbased
ionizing-radiation detectors possessing properties unachievable, for present time, for other materials. These
detectors have found the applications in a number of areas including thermonuclear plasma diagnostics at world leading
tokamaks and medical dosimetry.
Perfection and new developments of diamond-based detectors, including those on natural and synthetic crystals as well
as on CVD films, encounter a number of obstacles, the main of which is related to empirical approach to the
development in consequence of the lack of detailed understanding in physical mechanisms of such detector operation.
This paper is further development, theoretical and experimental, of our earlier proposed model of the operation of a
radiation detector based on high-resistivity semiconductor which first made it possible to explain main experimentally
observed peculiarities of characteristics of natural diamond detectors exposed to various kinds of radiation. The model is
based on the charge carrier recombination process that ensures the variation of carrier lifetimes depending on the space
charge value, in the whole detector volume. All calculations are conducted for two-level model of recombination which
fits this requirement. It is shown that a weak generation of free charge carriers from impurity levels in addition to the
main band-to-band generation can significantly increase the operation voltages of the detector. A decrease of detector
temperature is shown to widen the circle of the materials on which the detectors operating in accordance with the model
can be developed. Results of modeling of operation of the detector on detector samples based on silicon, as the most
perfect technologically developed material, are presented. The experimental studies were performed at a temperature of
14 K to ensure sufficiently low concentration of trapping impurity centers in this material. A technique is proposed for
evaluation of the concentration of trapping levels in high-resistivity semiconductors.
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