# US 12,119,419 B2 · Photodetector

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- Number: US 12,119,419 B2
- Document ID: US12119419B2
- Status: Granted
- Kind: B2
- Application number: 17/422,037
- Filed: 2020-01-15
- Published: 2022-03-31
- Granted: 2024-10-15
- Earliest claimed: 2019-01-16
- Assignees: Nippon Telegraph and Telephone Corporation
- Applicants: Nippon Telegraph and Telephone Corporation
- Inventors: Kotaro Takeda
- Web page: https://patentgrep.com/patent/US12119419B2

## CPC

- H10F 77/60: Arrangements for cooling, heating, ventilating or compensating for temperature fluctuations
- H10F 30/20: the devices having potential barriers, e.g. phototransistors
- H10F 39/18: Complementary metal-oxide-semiconductor [CMOS] image sensors; Photodiode array image sensors
- H10F 77/122: comprising only Group IV materials
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION

## Abstract

A photodetector having a sufficient ESD withstand voltage is provided. An embodiment of a photodetector includes a plurality of photodiodes including germanium or a germanium compound in a light absorption layer, and a plurality of heaters configured to apply heat to the light absorption layer of each of the plurality of photodiodes, in which the plurality of heaters are connected in series, the plurality of heaters are connected in parallel, or a plurality of sets of the plurality of heaters serially connected are connected in parallel.

## Claims

### Claim 1

A photodetector comprising:
a plurality of photodiodes including germanium or a germanium compound in a light absorption layer; and
a plurality of heaters configured to apply heat to the light absorption layer of each of the plurality of photodiodes, wherein each of the plurality of photodiodes is associated with one of the plurality of heaters,
wherein the plurality of heaters are connected in series, the plurality of heaters are connected in parallel, or a plurality of sets of the plurality of heaters serially connected are connected in parallel, wherein a collective width of the plurality of heaters when the plurality of heaters are connected in parallel and a collective length of the plurality of heaters are connected in series are configured to provide the photodetector with a sufficient electrostatic discharge withstand voltage.

### Claim 2 (depends on 1)

The photodetector according to claim 1, wherein a photodiode of the plurality of photodiodes includes:
a silicon substrate;
a lower clad layer formed on the silicon substrate;
a core layer formed on the lower clad layer and including a silicon slab doped with impurity ions having a first conductivity type, an electrode portion doped with the impurity ions having the first conductivity type at a high concentration, and a waveguide layer connected to the silicon slab;
a germanium layer formed on the core layer and including a germanium region doped with impurities having a second conductivity type;
an upper clad layer formed on the core layer and the germanium layer; and
electrodes connected to the electrode portion and the germanium region, respectively.

### Claim 3 (depends on 1)

The photodetector according to claim 1, wherein a photodiode of the plurality of photodiodes includes:
a silicon substrate;
a lower clad layer formed on the silicon substrate;
a core layer formed on the lower clad layer and including a silicon slab doped with impurity ions having a first conductivity type, and a waveguide layer connected to the silicon slab;
a germanium layer formed on the core layer and including a first germanium region doped with the impurity ions having the first conductivity type and a second germanium region doped with impurity ions having a second conductivity type;
an upper clad layer formed on the core layer and the germanium layer; and
electrodes connected to the first germanium region and the second germanium region, respectively.

### Claim 4 (depends on 1)

The photodetector according to claim 1, wherein a photodiode of the plurality of photodiodes includes:
a silicon substrate;
a lower clad layer formed on the silicon substrate;
a core layer formed on the lower clad layer and including a silicon slab, the silicon slab including a first silicon region doped with impurity ions having a first conductivity type, a first electrode portion doped with the impurity ions having the first conductivity type, a second silicon region doped with impurity ions having a second conductivity type, and a second electrode portion doped with the impurity ions having the second conductivity type, and a waveguide layer connected to the silicon slab;
a germanium layer formed on the core layer;
an upper clad layer formed on the core layer and the germanium layer; and
electrodes connected to the first electrode portion and the second electrode portion.

### Claim 5 (depends on 2)

The photodetector according to claim 2,
wherein a heater of the plurality of heaters is formed with a metal or metal compound embedded in the upper clad layer and the heater of the plurality of heaters is disposed directly above the light absorption layer, and
a width and a length of the heater are equal to or 1 μm larger than a width and a length of the light absorption layer, respectively.

### Claim 6 (depends on 2)

The photodetector according to claim 2, wherein a heater of the plurality of heaters is prepared by doping the core layer with impurities and wherein the heater is disposed around the light absorption layer.

### Claim 7 (depends on 5)

The photodetector according to claim 5, wherein a density of a current flowing through each of the plurality of heaters is 150 to 250 mA/μm2 or less.

### Claim 8 (depends on 5)

The photodetector according to claim 5, further comprising a capacitor connected in parallel with the heater.

### Claim 9 (depends on 3)

The photodetector according to claim 3,
wherein a heater of the plurality of heaters is formed with a metal or metal compound embedded in the upper clad layer and wherein the heater is disposed directly above the light absorption layer, and
a width and a length of the heater are equal to or 1 μm larger than a width and a length of the light absorption layer, respectively.

### Claim 10 (depends on 4)

The photodetector according to claim 4,
wherein a heater of the plurality of heaters is formed with a metal or metal compound embedded in the upper clad layer and wherein the heater is disposed directly above the light absorption layer, and
a width and a length of the heater are equal to or 1 μm larger than a width and a length of the light absorption layer, respectively.

### Claim 11 (depends on 3)

The photodetector according to claim 3, wherein a heater of the plurality of heaters is prepared by doping the core layer with impurities and wherein the heater is disposed around the light absorption layer.

### Claim 12 (depends on 4)

The photodetector according to claim 4, wherein a heater of the plus of heaters is prepared by doping the core layer with impurities and wherein the heater is disposed around the light absorption layer.

### Claim 13 (depends on 6)

The photodetector according to claim 6, wherein a density of a current flowing through each of the plurality of heaters is 150 to 250 mA/μm2 or less.

### Claim 14 (depends on 6)

The photodetector according to claim 6, further comprising a capacitor connected in parallel with the heater.