Apparatus and methods for charge collection control in radiation detectors

Patent metadata

Field	Value
Publication number	US-9261609-B2
Application number	US-201213589853-A
Country	US
Kind code	B2
Filing date	Aug 20, 2012
Priority date	Aug 20, 2012
Publication date	Feb 16, 2016
Grant date	Feb 16, 2016

Abstract

Apparatus and methods for charge collection control in radiation detectors are provided. One radiation detector includes a semiconductor substrate, at least one cathode on a surface of the semiconductor substrate, and a plurality of anodes on a surface of the semiconductor substrate opposite the at least one cathode, wherein the plurality of anodes have gaps therebetween. The radiation detector further includes a charge collection control arrangement configured to cause one or more charges induced within the semiconductor substrate by incident photons to drift towards one or more of the plurality of anodes.

First claim

What is claimed is:

1. A radiation detector comprising:
a semiconductor substrate;
at least one cathode on a surface of the semiconductor substrate;
a plurality of anodes on a surface of the semiconductor substrate opposite the at least one cathode, the plurality of anodes having gaps therebetween; and
a charge collection control arrangement configured to vary a voltage of at least one of a group of adjacent anodes in response to a detected shared charge between at least two of the adjacent anodes, to cause the detected shared charge to drift towards one anode of the at least two anodes, the detected shared charge induced within the semiconductor substrate by an incident photon.

2. The radiation detector of claim 1 , wherein the charge collection control arrangement is configured to prevent surface recombination of one or more charges at the gaps between the anodes.

3. The radiation detector of claim 1 , wherein the charge collection control arrangement is configured to shift a charge sharing line within the semiconductor substrate to shift a voxel position.

4. The radiation detector of claim 3 , wherein the voxel position is shifted to include at least one of the anodes, wherein the detected shared charge is collected by the one anode of the at least two anodes.

5. The radiation detector of claim 4 , wherein the shifted voxel maintains an area and volume thereof.

6. The radiation detector of claim 1 , wherein the charge control arrangement comprises a plurality of switches and resistors forming a voltage divider to bias the plurality of anodes.

7. The radiation detector of claim 6 , wherein the charge control arrangement comprises a plurality of comparators electrically coupled to the anodes and configured to identify electrical signals that exceed a threshold level.

8. The radiation detector of claim 7 , wherein the charge control arrangement comprises a control unit to control the switching of the switches based on an output signal from the comparators.

9. The radiation detector of claim 8 , wherein the control unit controls the switches to change an equivalent resistance produced by the resistors in one or more electronic channels of the anodes.

10. The radiation detector of claim 8 , wherein the control unit controls the switches to bias all of the anodes except for two with a same bias voltage.

11. The radiation detector of claim 1 , wherein the charge control arrangement is implemented in an application-specific integrated circuit (ASIC).

12. The radiation detector of claim 1 , wherein the charge control arrangement is configured to change a relative voltage of at least two anodes immediately surrounding a center pixel to shift a charge sharing line within the semiconductor substrate, wherein a voltage of one of the at least two anodes is increased and a voltage of another of the at least two anodes is decreased.

13. The radiation detector of claim 12 , wherein the charge sharing line is shifted about 200 μm.

14. The radiation detector of claim 1 , wherein the charge control arrangement comprises a plurality of switches selectively connectable to a plurality of resistors and forming a voltage divider to bias the plurality of anodes, wherein the plurality of switches have three different switch positions to connect to different ones of the plurality of resistors that are connected in parallel with a corresponding resistor, the switching of the plurality of switches configured to account for a parasitic capacitance of the radiation detector.

15. The radiation detector of claim 1 , wherein the charge control arrangement comprises a plurality of switches having a plurality of switch positions selectively connectable to a corresponding voltage source.

16. The radiation detector of claim 1 , wherein the anodes of the group of adjacent anodes are biased to a common initial bias voltage before the voltage of the at least one of the group of adjacent anodes is varied.

17. A radiation detector comprising:
a semiconductor substrate;
at least one cathode on a surface of the semiconductor substrate;
a plurality of anodes on a surface of the semiconductor substrate opposite the at least one cathode, the plurality of anodes having gaps therebetween; and
a charge collection control arrangement having a plurality of switches and resistors forming a voltage divider to bias the plurality of anodes, and further comprising a control unit to control the switching of the switches to vary a voltage of at least one of a group of adjacent anodes in response to a detected shared charge between at least two of the adjacent anodes, to shift a charge sharing line within the semiconductor substrate to cause the detected share charge to drift towards one anode of the at least two of the adjacent anodes, the detected shared charge induced within the semiconductor substrate by an incident photon.

18. The radiation detector of claim 17 , wherein the charge collection control arrangement is configured to prevent surface recombination of one or more charges at the gaps between the anodes.

19. The radiation detector of claim 17 , wherein the charge control arrangement comprises a plurality of comparators electrically coupled to the anodes and configured to identify electrical signals that a exceed a threshold level, wherein the control unit is configured to control the switching of the switches based on an output signal from the comparators to change an equivalent resistance produced by the resistors in one or more electronic channels of the anodes.

20. The radiation detector of claim 19 , wherein the control unit controls the switches to bias all of the anodes except for two with a same bias voltage.

21. The radiation detector of claim 17 , wherein the charge control arrangement is implemented in an application-specific integrated circuit (ASIC).

22. The radiation detector of claim wherein the charge control arrangement is configured to change a relative voltage of anodes surrounding a center pixel to shift a charge sharing line within the semiconductor substrate about 200 μm.

23. A method for controlling charge collection in a pixelated radiation detector, the method comprising:
coupling a charge control arrangement to a pixelated radiation detector; and
controlling charge collection of the pixelated radiation detector with the charge control arrangement using a plurality of switches and resistors forming a voltage divider to bias a plurality of anodes of the pixelated radiation detector by controlling the switching of the switches to vary a voltage of at least one of a group of adjacent anodes in response to a detected shared charge between at least two of the adjacent anodes, to shift a charge sharing line within a semiconductor substrate of the pixelated radiation detector to cause the detected shared charge to drift towards one anode of the at least two of the adjacent anodes, the detected shared charge induced within the semiconductor substrate by an incident photon.

24. The method of claim 23 , further comprising providing the charge control arrangement in an application-specific integrated circuit (ASIC).

Assignees

• Shahar Arie
• Traub Eliezer
• Glazer Yaron
• Blevis Ira Micah
• Gen Electric

Inventors

• Shahar Arie
• Traub Eliezer
• Glazer Yaron
• Blevis Ira Micah

Classifications

• G01T1/247

  Detector read-out circuitry (for processing gain or off-set correction H04N) · CPC title

• G01T1/241 Primary

  Electrode arrangements, e.g. continuous or parallel strips or the like · CPC title