Patent ID: 7652258

Claim:
A method of reducing polarization in a photon counting semiconductor radiation detector for computed tomography (CT), the method comprising: generating an electrical signal in response to absorption of high flux X-ray radiation in a CdZnTe (CZT) pixilated detector including a monolithic semiconductor plate having a monolithic cathode electrode and pixilated anode electrodes coupled thereto, wherein generating the electrical signal includes generating the electrical signal in the anode electrodes by electron motion towards the anodes, in response to absorption of the high flux X-ray radiation in the semiconductor plate, wherein the absorption of the high flux X-ray radiation creates an inhomogeneous positive space charge in the semiconductor plate, wherein the inhomogeneous positive space charge produces a polarization effect in the semiconductor plate by an attraction of electrons to the cathode electrode, wherein the polarization effect causes a reduction in the electron motion towards the anode electrodes, thereby to reduce the electrical signal generated in the anode electrodes, and wherein the semiconductor plate comprises a trap level having an energy level between a valence band and a conduction band of the semiconductor plate; selecting, in response to the energy level of the trap level and creation of the space charge, one or more wavelengths of infra-red (IR) radiation to which the semiconductor plate is at least partially transparent along the whole range between the anode and cathode electrodes; and optically coupling the IR radiation of selected wavelength into the semiconductor plate via the cathode electrode, which is at least partially transparent to the IR radiation, to cause electron transitions from the trap level to the valance band, so as to generate trapped positive charges in the semiconductor plate and to homogenize the positive space charge by producing a substantially uniform space charge over all of the semiconductor plate, and so as to reduce the polarization and the attraction of the electrons to the cathode electrode by the inhomogeneous space charge, thereby to improve a drift of the electrons toward the anode electrode, wherein the pixilated detector is mounted, together with an IR generator capable of generating the IR radiation, on an arc-like shape carrier of a CT system, which is associated with an X-ray source capable of generating the X-ray radiation.