Photo detector array of geiger mode avalanche photodiodes for computed tomography systems
AssigneeSTMicroelectronics S.r.l.
InventorsDelfo Nunziato SANFILIPPO, Giovanni CONDORELLI
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Abstract
The photo detector array is configured to generate pulses with short rise and fall times because each Geiger mode avalanche photodiode includes an anode contact, a cathode contact, an output contact electrically insulated from the anode and cathode contacts, a semiconductor layer, and at least one shield or metal structure in the semiconductor layer capacitively coupled to the semiconductor layer and coupled to the output contact. The output contacts of all Geiger mode avalanche photodiodes are connected in common and are configured to provide for detection of spikes correlated to avalanche events on any avalanche photodiode of the array.
Claims20
A photodetector array comprising:
- a semiconductor substrate;
- an array of Geiger mode avalanche photodiodes on the semiconductor substrate configured to detect radiation, each Geiger mode avalanche photodiode comprising
- an anode contact,
- a cathode contact,
- an output contact electrically insulated from said anode and cathode contacts,
- a semiconductor layer,
- a front side metallization layer on the semiconductor layer, and
- at least one shield structure in said semiconductor layer capacitively coupled to said semiconductor layer and coupled to said output contact;
- a first connection lead defined by a common cathode contact of the array photodiode cathode contacts;
- a second connection lead defined by a common anode collecting grid contact, patterned in the front side metallization layer of the semiconductor layer, connecting in common the anode contacts of the array photodiodes;
- and
- an array output defined by the array photodiodes output contacts connected in common.
A computed tomography system comprising:
- a photodetector array including
- a semiconductor substrate,
- an array of Geiger mode avalanche photodiodes on the semiconductor substrate configured to detect radiation, each Geiger mode avalanche photodiode comprising
- an anode contact,
- a cathode contact,
- an output contact electrically insulated from said anode and cathode contacts,
- a semiconductor layer,
- a front side metallization layer on the semiconductor layer, and
- at least one shield structure in said semiconductor layer capacitively coupled to said semiconductor layer and coupled to said output contact,
- a first connection lead defined by a common cathode contact of the array photodiode cathode contacts,
- a second connection lead defined by a common anode collecting grid contact, patterned in the front side metallization layer of the semiconductor layer, connecting in common the anode contacts of the array photodiodes, and
- an array output defined by the array photodiodes output contacts connected in common;
- and
- a counter configured to count spikes corresponding to avalanche events on said array output of the Geiger mode avalanche photodiodes.
A method of detecting radiation with a photodetector array, the method comprising:
- forming an array of Geiger mode avalanche photodiodes on a semiconductor substrate, each Geiger mode avalanche photodiode comprising
- an anode contact,
- a cathode contact,
- an output contact electrically insulated from the anode and cathode contacts,
- a semiconductor layer,
- a front side metallization layer on the semiconductor layer, and
- at least one shield structure in the semiconductor layer capacitively coupled to he semiconductor layer and coupled to the output contact;
- coupling the array photodiode cathode contacts to a common cathode contact to define a first connection lead;
- coupling the anode contacts of the array photodiodes to a common anode collecting grid contact, patterned in the front side metallization layer of the semiconductor layer, to define a second connection lead;
- and
- coupling in common the array photodiodes output contacts to an array output.
Dependencies are inferred from the claim text.