Negative feedback avalanche diode
View Patent ↗A single-photon avalanche detector is disclosed that is operable at wavelengths greater than 1000 nm and at operating speeds greater than 10 MHz. The single-photon avalanche detector comprises a thin-film resistor and avalanche photodiode that are monolithically integrated such that little or no additional capacitance is associated with the addition of the resistor.
1. An article comprising a first detector that is characterized by a first RC time constant, wherein the first detector comprises:
a first photodiode for producing a first electrical signal in response to receipt of a single photon that has a wavelength greater than 1000 nm, wherein the first photodiode has a first doped region that has a first perimeter, and wherein the first photodiode is characterized by a first photodiode capacitance, C p1 ; and
a first thin-film resistor;
wherein the first thin-film resistor and the first photodiode are electrically connected and monolithically integrated such that (1) the first thin-film resistor is disposed above the first doped region and located substantially completely within the first perimeter and (2) the effect of the integration of the first thin-film resistor on the first RC time constant is less than approximately 5%.
2. The article of claim 1 wherein C D1 is substantially equal to C p1 .
3. The article of claim 1 wherein the first active region has a diameter that is less than or equal to 15 microns.
4. The article of claim 1 further comprising a second detector, wherein the second detector comprises:
a second photodiode for producing a second electrical signal in response to receipt of a single photon that has a wavelength greater than 1000 nm, wherein the first photodiode and the second photodiode are monolithically integrated, and wherein the second photodiode has a second doped region that has a second perimeter, and wherein the second photodiode is characterized by a second photodiode capacitance, C p2 ; and
a second thin-film resistor, wherein the second thin-film resistor and the second photodiode are monolithically integrated and electrically-connected, and wherein the second thin-film resistor is disposed above the second doped region, and further wherein the second thin-film resistor is located substantially completely within the second perimeter;
wherein the second detector is characterized by a second detector capacitance, C D2 , and wherein C D2 is within the range of approximately C p2 to approximately 1.05 C p2 .
5. The article of claim 4 wherein:
the first resistor has a first terminal and a second terminal, and the first terminal and the first photodiode are electrically-connected;
the second resistor has a third terminal and a fourth terminal, and the third terminal and the second photodiode are electrically-connected; and
the second terminal and the fourth terminal are electrically-connected.
6. An article comprising a first detector that is characterized by a first RC time constant, wherein the first detector comprises:
a first avalanche photodiode that is physically adapted to provide an electrical signal in response to a received photon having a wavelength greater than 1000 nm, wherein the first avalanche photodiode comprises a first active region having a first perimeter, and wherein the first photodiode is characterized by a first photodiode capacitance, C p1 ; and
a first thin-film resistor having a first terminal and a second terminal, wherein the first thin-film resistor resides substantially completely within the first perimeter, and wherein the first thin-film resistor is characterized by a first resistance, R, between the first terminal and the second terminal, and further wherein the first resistance is within the range of approximately 10 kΩ to approximately 10 MΩ;
wherein the first terminal and the first active region are electrically connected; and
wherein the first avalanche photodiode and the first thin-film resistor are monolithically integrated such that the effect of the integration of the first thin-film resistor on the first RC time constant is less than approximately 5%.
7. The article of claim 6 further comprising a second detector, wherein the second detector comprises:
a second avalanche photodiode that is physically adapted to provide an electrical signal in response to a received photon having a wavelength greater than 1000 nm, wherein the second avalanche photodiode comprises a second active region having a second perimeter, and wherein the second photodiode is characterized by a second photodiode capacitance, C p2 ; and
a second thin-film resistor having a third terminal and a fourth terminal, wherein the second thin-film resistor resides substantially completely within the second perimeter, and wherein the second thin-film resistor is characterized by a second resistance between the third terminal and the fourth terminal, and further wherein the second resistance is within the range of approximately 10 kΩ to approximately 10 MΩ;
wherein the second avalanche photodiode and the second thin-film resistor are monolithically integrated;
wherein the third terminal and the second active region are electrically connected; and
wherein the second detector is characterized by a second detector capacitance, C D2 , and wherein C D2 is within the range of approximately C p2 to approximately 1.05 C p2 .
8. The article of claim 7 wherein the second terminal and the fourth terminal are electrically connected.
9. The article of claim 8 wherein the first avalanche photodiode and the second avalanche photodiode are monolithically integrated on a substrate.
10. The article of claim 6 wherein the first avalanche photodiode and the first thin-film resistor collectively define an RC time constant, and wherein the RC time constant is less than 100 ns.
11. The article of claim 6 wherein C D1 is substantially equal to C p1 .
12. The article of claim 6 further comprising a first plurality of second detectors, wherein the first detector and the first plurality of second detectors are electrically connected in parallel and collectively define a detector array, and wherein each of the first plurality of second detectors comprises:
a second avalanche photodiode that is physically adapted to provide an electrical signal in response to a received photon having a wavelength greater than 1000 nm, wherein the second avalanche photodiode comprises a second active region having a second perimeter, and wherein the second photodiode is characterized by a second photodiode capacitance, C p2 ; and
a second thin-film resistor having a third terminal and a fourth terminal, wherein the second thin-film resistor is monolithically integrated with the second avalanche photodiode and resides substantially completely within the second perimeter, and wherein the second thin-film resistor is characterized by a second resistance between the third terminal and a fourth terminal, and further wherein the second resistance is within the range of approximately 10 kΩ to approximately 10 MΩ;
wherein the second terminal and each of the fourth terminals are electrically connected at a common output terminal, and wherein each detector of the detector array is characterized by an avalanche/rearming cycle, and further wherein the common output terminal provides an output signal having a magnitude that indicates the number of detectors of the detector array that have received a photon within the avalanche/rearming cycle of a first photon receiving detector.
13. The article of claim 1 further comprising a first plurality of second detectors, wherein the first detector and the first plurality of second detectors are electrically connected in parallel and collectively define a detector array, and wherein each of the first plurality of second detectors comprises: a second photodiode for producing a second electrical signal in response to a received photon that has a wavelength greater than 1000 nm, wherein the second avalanche photodiode has a second doped region that has a second perimeter, and wherein the second photodiode is characterized by a second photodiode capacitance, Cp 2 ; and a second thin-film resistor having a third terminal and a fourth terminal, wherein the second thin-film resistor and the second photodiode are monolithically integrated and electrically connected, and wherein the second thin-film resistor is disposed above the second doped region, and further wherein the second thin-film resistor is located substantially completely with the first perimeter; wherein each detector of the detector array is characterized by an avalanche/rearming cycle, and wherein the detector array provides an output signal having a magnitude that indicates the number of detectors of the detector array that have received a photon within the avalanche/rearming cycle of a first photon receiving detector.