Infra-red light stimulated cdZnTe spectroscopic semiconductor x-ray and gamma-ray radiation detector
A method of detecting radiation by which residence time of charge carriers is dramatically reduced by an external optical energy source and the occupancy of deep-level defects is maintained close to the thermal equilibrium of the un-irradiated device at any temperature. The energy of an infra-red light source is tuned within a predetermined band gap energy range and crystals are transparent to the infra-red light of the energy. Thus, other than the one associated with the ionization of the target deep-level defects, no other absorption occurs. Because of this low absorption, infra-red irradiation can be performed through any surface of the crystal that is transparent to the infra-red light which allows irradiation geometry from any side surface(s) of the detector crystals.
1 . A radiation detector comprising:
an external optical energy source to provide sufficient energy for trapped charged carriers to escape from defect levels; and
crystals that are transparent to the light of the energy source allowing no additional absorption.
2 . The radiation detector of claim 1 , wherein the external optical energy source is an infra-red light source.
3 . The radiation detector of claim 2 , wherein the energy of the infra-red light source is tuned within the band gap energy range of ˜0.5-0.6 eV.
4 . The radiation detector of claim 2 , wherein the transparent crystals are made of Cadmium Zinc Telluride.
5 . A method of detecting radiation comprising energy of an external infra-red light source tuned within the band gap energy range of ˜0.5-0.8 eV to interact with transparent crystals, the steps comprising:
a) causing the occupancy of the deep-level defects to be maintained close to the thermal equilibrium of the un-irradiated device at any temperature;
b) allowing trapped carriers to escape from the defect levels; and
c) causing the residence time of charge carriers to be dramatically reduced by the external infra-red energy source.