Photodiode and method for operating a photodiode

Patent metadata

Field	Value
Publication number	US-12009439-B2
Application number	US-202017996914-A
Country	US
Kind code	B2
Filing date	Apr 24, 2020
Priority date	Apr 24, 2020
Publication date	Jun 11, 2024
Grant date	Jun 11, 2024

Abstract

In an embodiment a photodiode includes a semiconductor body having a light entrance side and a back side opposite the light entrance side, a first electrode at the light entrance side atop a first doped area of a first conductivity type, a second electrode at the light entrance side atop a second doped area of a second conductivity type, the second doped area being configured to absorb radiation, a gate region at the light entrance side at least between the first electrode and the second electrode, the gate region being connected to a gate electrode, a base electrode at the semiconductor body, the base electrode being configured to receive a current flow from the first electrode, the current flow being indicative of a radiant flux of the radiation onto the second doped area and a radiation shield covering and shielding the first doped area from the radiation to be detected.

First claim

The invention claimed is:

1. A photodiode comprising:
a semiconductor body having a light entrance side and a back side opposite the light entrance side;
a first electrode at the light entrance side atop a first doped area of a first conductivity type;
a second electrode at the light entrance side atop a second doped area of a second conductivity type, the second doped area being configured to absorb radiation to be detected and thereby to generate charge carriers;
a gate region at the light entrance side at least between the first electrode and the second electrode, the gate region being connected to a gate electrode;
a base electrode at the semiconductor body, the base electrode being configured to receive a current flow from the first electrode, the current flow being indicative of a radiant flux of the radiation onto the second doped area; and
a radiation shield covering and shielding the first doped area and the gate region from the radiation to be detected,
wherein the photodiode is configured to, upon applying a reverse bias voltage between the first electrode and the second electrode and upon applying a gate voltage to the gate electrode, balance a depletion at the first doped area by generated charge carriers from the second doped area based on the current flow between the base electrode and the first electrode.

2. The photodiode according to claim 1 , wherein the radiation shield completely covers the first doped area and the gate region, wherein the second doped area is distant from the radiation shield, seen in a top view onto the light entrance side, and wherein the radiation shield is electrically insulated at least from the first electrode, the second electrode and the gate electrode.

3. The photodiode according to claim 1 , wherein the radiation shield is of at least one metal, and wherein the radiation shield is electrically insulated from the semiconductor body and is not electrically functionalized in the photodiode.

4. The photodiode according to claim 1 , further comprising a substrate onto which the semiconductor body is grown, wherein the substrate is of the first conductivity type, and wherein the semiconductor body as a whole is weakly doped and is also of the first conductivity type.

5. The photodiode according to claim 1 , wherein the base electrode is located at the back side of the semiconductor body.

6. The photodiode according to claim 1 , wherein the base electrode is located at the light entrance side of the semiconductor body.

7. The photodiode according to claim 1 , wherein the gate region completely surrounds the first electrode, seen in a top view onto the light entrance side.

8. The photodiode according to claim 1 , further comprising a third electrode atop a third doped area of the second conductivity type, wherein the first electrode is located between the second electrode and the third electrode, and wherein a junction between the first electrode and the third electrode is configured to be forward biased.

9. The photodiode according to claim 8 , wherein the third electrode is configured for signal amplification of the current flow between the base electrode and the first electrode, and wherein the third electrode as well as an entire area between the third electrode and the first electrode are completely covered by the radiation shield.

10. The photodiode according to claim 1 , further comprising a plurality of the second electrodes and of associated second doped areas, wherein the second electrodes and the associated second doped areas are sensitive for different spectral regions of the radiation to be detected.

11. The photodiode according to claim 10 , wherein the second electrodes are individually addressable, and wherein a number of the second electrodes is between 2 and 16, inclusive, and all the second electrodes are assigned to the same first electrode.

12. The photodiode according to claim 10 , wherein the first electrode is a line segment and the second electrodes are arranged along this line segment when seen in a top view onto the light entrance side.

13. A method for operating a photodiode, wherein the photodiode comprises a semiconductor body having a light entrance side and a back side opposite the light entrance side, a first electrode at the light entrance side atop a first doped area of a first conductivity type, a second electrode at the light entrance side atop a second doped area of a second conductivity type, the second doped area for absorbing radiation to be detected and thereby to generate charge carriers, a gate region at the light entrance side at least between the first electrode and the second electrode, the gate region being connected to a gate electrode, a base electrode at the semiconductor body, the base electrode for receiving a current flow from the first electrode, the current flow being indicative of a radiant flux of the radiation onto the second doped area and a radiation shield covering and shielding the first doped area and the gate region from the radiation to be detected, the method comprising:
applying a reverse bias voltage between the first electrode and the second electrode,
applying a gate voltage to the gate electrode;
balancing a depletion at the first doped area by generated charge carriers from the second doped area; and
enabling the balancing of the depletion by the current flow between the base electrode and the first electrode.

14. The method according to claim 13 , further comprising using the photodiode without a third electrode, wherein the current flow is used as it is as a measurement signal for the radiant flux.

15. The method according to claim 13 , further comprising:
amplifying the current flow by a third electrode,
wherein a measurement signal for the radiant flux is a time delay between a reset of the photodiode and a beginning of the amplified current flow.

16. The method according to claim 13 , further comprising:
receiving, by the photodiode, an optical input;
converting, by the photodiode, the optical input into an electrical signal;
feeding the electrical signal to a transimpedance amplifier, then to a filter and then to an analog-to-digital converter; and
outputting, by the analog-to-digital converter, a digitalized signal representative of the optical input.

17. The method according to claim 13 , further comprising:
receiving, by the photodiode, an optical input;
converting, by the photodiode, the optical input into an electrical signal;
feeding the electrical signal to a time-to-digital converter; and
outputting, by the time-to-digital converter, a digitalized signal representative for the optical input.

18. A photodiode comprising:
a semiconductor body having a light entrance side and a back side opposite the light entrance side;
a first electrode at the light entrance side atop a first doped area of a first conductivity type;
a second electrode at the light entrance side atop a second doped area of a second conductivity type, the second doped area being configured to absorb radiation to be detected and thereby to generate charge carriers;
a third electrode atop a third doped area of the second conductivity type;
a gate region at the light entrance side at least between the first electrode and the second electrode, the gate region being connected to a gate electrode,
a base electrode at the semiconductor body, the base electrode being configured to receive a current flow from the first electrode, the current flow being indicative of a radiant flux of the radiation onto the second doped area; and
a radiation shield

Assignees

• Ams Osram Int Gmbh

Inventors

• Mazzillo Massimo Cataldo
• Boescke Tim

Classifications

• H10F77/50

  Encapsulations or containers (for photovoltaic modules H10F19/80) · CPC title

• H10F30/223

  the potential barrier being a PIN barrier · CPC title

• H10F30/24

  the devices having only two potential barriers, e.g. bipolar phototransistors · CPC title

• H10F77/953 Primary

  for devices having potential barriers · CPC title

• H10F77/334 Primary

  for shielding light, e.g. light blocking layers or cold shields for infrared detectors · CPC title