Proximity charge sensing for semiconductor detectors

A method of non-contact charge sensing comprising:

• providing a semiconductor detector of having a first surface and an opposing second surface of a substrate;
• disposing a high resistivity first surface electrode layer on the first surface of the substrate;
• disposing a low resistivity first surface electrode on a portion of the high resistivity first surface electrode layer, wherein an area portion of the high resistivity electrode layer is exposed;
• disposing a low resistivity second surface electrode layer on the second surface of the semiconductor detector;
• applying a voltage between the first surface low resistivity electrode and the second surface low resistivity electrode to cause a free charge to drift toward the high resistivity electrode layer on the first surface or the low resistivity electrode on the second surface according to a polarity of the free charge and the polarity of the applied voltage;
• providing at least one non-contact electrode disposed at a selected distance apart from the exposed high resistivity first surface electrode layer, the at least one non-contact electrode configured to have a signal induced in it in response to the movement of the free charge within the semiconductor detector, in which the high resistivity first surface electrode layer induces the signal on the non-contact electrode;
• and
• providing a charge sensitive preamplifier coupled to the non-contact electrode to output a signal in response to the free charge within the detector arriving at the high resistivity first surface electrode.

A non-contact charge sensor having a reduced spectral background, comprising:

• a semiconductor detector having a first surface and an opposing second surface and sides, the detector comprising:
• a first electrode on the first surface;
• a second electrode on the second surface;
• a voltage applied between the first electrode and the second electrode to cause a free charge to drift toward the first or second electrode according to a polarity of the free charge and the polarity of the applied voltage;
• a first charge sensitive preamplifier coupled to the first electrode to output a signal in response to a movement of the free charge within the detector;
• at least one non-contact electrode spaced apart from the sides of the detector between the first and second surfaces configured to capture signal charges generated inside the detector at one of the sides of the detector;
• a second charge-sensitive preamplifier coupled to the non-contact electrode to output a signal in response to the free charge within the detector arriving at the sides of the detector;
• and
• an anticoincidence processor to correct for an incomplete charge accumulation at the first electrode by comparing the output from the first charge-sensitive preamplifier to the output from the second charge-sensitive preamplifier.

A method of non-contact charge sensor having a reduced spectral background, comprising:

• providing a semiconductor detector having a first surface and an opposing second surface;
• providing a first electrode on the first surface;
• providing a second electrode on the second surface;
• applying a voltage between the first electrode and the second electrode to cause a free charge to drift toward the first or the second electrode according to a polarity of the free charge and the polarity of the applied voltage;
• providing a first charge sensitive preamplifier coupled to the first electrode to output a signal in response to a movement of the free charge within the detector;
• providing at least one non-contact electrode spaced apart from and opposite the sides between the first and second surfaces of the detector, the non-contact electrode configured to capture signal charges generated inside the detector at one of the sides of the detector;
• providing a second charge-sensitive preamplifier coupled to the non-contact electrode to output a signal in response to the free charge within the detector arriving at the sides of the detector;
• and
• providing an anticoincidence processor to correct for an incomplete charge accumulation at the first electrode by comparing the output from the first charge-sensitive preamplifier to the output from the second charge-sensitive preamplifier.

A non-contact charge sensor having a reduced spectral background, comprising:

• a semiconductor detector having a first surface and an opposing second surface and sides between the first and second surfaces, the detector comprising:
• a first electrode on the first surface;
• a second electrode on the second surface;
• a voltage applied between the first electrode and the second electrode to cause a free charge to drift toward the first or second electrode according to a polarity of the free charge and the polarity of the applied voltage;
• at least one non-contact electrode spaced apart from and opposite the sides of the detector, the non-contact electrode configured to capture signal charges generated inside the detector at one of the sides of the detector;
• and
• a processor to correct for an incomplete charge accumulation at the first electrode by comparing the output from the first electrode and the non-contact electrode.

A method of non-contact charge sensor having a reduced spectral background, comprising:

• providing a semiconductor detector having a first surface and an opposing second surface;
• providing a first electrode on the first surface;
• providing a second electrode on the second surface;
• applying a voltage between the first electrode and the second electrode to cause a free charge to drift toward the first or the second electrode according a polarity of the free charge and the polarity of the applied voltage;
• providing at least one non-contact electrode spaced apart from and opposite the sides of the detector, the non-contact electrode configured to capture signal charges generated inside the detector at one of the sides of the detector;
• and
• providing an anticoincidence processor to correct for an incomplete charge accumulation at the first electrode by comparing the output from the first electrode to the output from the non-contact electrode.