Photodetector with series capacitor

Abstract

An optical communication receiver includes a photodiode and signal processing circuitry coupled to the photodiode. The photodiode is configured to receive a modulated optical signal conveying data and to convert the modulated optical signal to an electrical signal. The photodiode includes a waveguide configured to receive the modulated optical signal, an absorption region over the waveguide, and a capacitor electrically coupled in series with the absorption region, thereby reducing a capacitance of the photodiode compared to a scenario in which the capacitor is omitted from the photodiode. The signal processing circuitry is configured to process the electrical signal to extract and output the data.

Description

Cross-reference to related applications

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 627,768, filed January 31, 2024, entitled “High-Speed ​​Photodetector with Series Capacitors,” which is incorporated herein by reference in its entirety for all purposes. Technical Field

[0002] This disclosure relates generally to optical communication technologies, and more specifically to high-speed photodetectors and high-speed photodiodes. Background Technology

[0003] The methods described in this Background section are methods that can be adopted, but need not be methods that have been previously conceived or adopted. Therefore, unless otherwise stated, it should not be assumed that any method described in this section qualifies as prior art simply by virtue of its inclusion in this section.

[0004] Network speed requirements are rapidly evolving. For example, in the early days of the internet, popular applications were limited to email, electronic bulletin boards, and primarily informational and text-based web browsing, typically transmitting relatively small amounts of data compared to today. Now, internet and mobile communication applications require enormous bandwidth (even compared to 15 years ago) to transmit photos, videos, music, and other multimedia files. For instance, some popular social media networks generate approximately 4 petabytes (PB) of data per day. Due to the ever-increasing demand for communication bandwidth, existing data communication systems must continuously increase their capacity.

[0005] Optical communication is an important technological field that is being developed to address the growing bandwidth demands of communication networks. Silicon photonics (SiPho) is becoming more prevalent and promises to bring ease of fabrication and compact form factors to optical communication systems.

[0006] In SiPho optical communication devices that use waveguide photodiodes (PDs), one obstacle to increasing transmission speed is the bandwidth limitation of the waveguide PD. A photodiode is a type of photodetector that uses semiconductors to convert light into electrical signals, while a photodetector is a general term for a device that converts light into electrical signals. Summary of the Invention

[0007] In one embodiment, an optical communication receiver includes a photodiode configured to receive a modulated optical signal for transmitting data and convert the modulated optical signal into an electrical signal. The photodiode includes a waveguide configured to receive the modulated optical signal; an absorption region located above the waveguide; and a capacitor electrically coupled in series with the absorption region, thereby reducing the capacitance of the photodiode compared to a scenario where the capacitor is omitted from the photodiode. The optical communication receiver also includes a signal processing circuitry coupled to the photodiode, the signal processing circuitry being configured to process the electrical signal to extract and output the data.

[0008] In another embodiment, the photodiode for converting a modulated optical signal for transmitting data into an electrical signal includes: a waveguide configured to receive the modulated optical signal; an absorption region above the waveguide; and a capacitor electrically coupled in series with the absorption region, thereby reducing the capacitance of the photodiode compared to a scenario where the capacitor is omitted from the photodiode.

[0009] In another embodiment, a method for manufacturing a photodiode includes: fabricating a waveguide on a semiconductor substrate, the waveguide being configured to receive a modulated optical signal for transmitting data; fabricating an absorption region above the waveguide; and fabricating a capacitor electrically coupled in series with the absorption region, thereby reducing the capacitance of the photodiode compared to a scenario where the capacitor is omitted from the photodiode. Attached Figure Description

[0010] Figure 1 This is a simplified block diagram of an example optical communication receiver according to an embodiment, which includes a waveguide photodiode (PD) having a capacitor connected in series with a PIN diode to increase the carrier transport bandwidth of the waveguide PD.

[0011] Figure 2A -B is a simplified block diagram of an example waveguide PD according to an embodiment, which includes... Figure 1 In the optical communication receiver.

[0012] Figure 2C This is a simplified block diagram of another example waveguide PD according to another embodiment, which includes... Figure 1 In the optical communication receiver.

[0013] Figure 3 It is according to the embodiment for manufacturing waveguide PD (such as Figure 2A -B Example waveguide PD and / or Figure 2C The flowchart shows an example method for an example waveguide PD. Detailed Implementation

[0014] Silicon photonics (SiPho) waveguide photodiodes (PDs) typically consist of a germanium (Ge) light-absorbing region above a silicon (Si) waveguide, which, together with a doped layer above the Ge light-absorbing region, forms a PIN diode. The bandwidth f of such a PD can be modeled as: Equation 1 in f LRC It refers to the bandwidth of the waveguide PD's inductance (L), resistance (R), and capacitance (C), while f TR It is the carrier transmission bandwidth of the waveguide PD. f LRC The bandwidth is based on the RC time constant of the waveguide PD's series resistance and junction capacitance. Carrier transport bandwidth. f TR The thickness of the Ge light-absorbing region, which is limited by the PIN diode, determines the carrier transport time across the PIN diode. Specifically, the carrier transport bandwidth... f TR It is inversely proportional to the thickness of the Ge light absorption region.

[0015] Increase carrier transmission bandwidth f TR This helps increase the bandwidth of waveguide PDs. f Therefore, reducing the thickness of the Ge optical absorption region helps to increase the carrier transport bandwidth. f TR However, reducing the thickness of the Ge absorption region increases the junction capacitance of the waveguide PD, which reduces the LCR bandwidth. f LRC To offset the increase in junction capacitance when the thickness of the Ge light-absorbing region is reduced, the length and / or width of the Ge light-absorbing region can be reduced. However, reducing the length and / or width of the Ge light-absorbing region sacrifices the waveguide PD's responsivity to photo-current conversion. In particular, because the length and / or width of the Ge light-absorbing region are reduced, there is less area available for light absorption, and / or less area available for connection to the metal layer.

[0016] In the waveguide PD embodiments described herein, the thickness of the optical absorption region is reduced compared to other implementations, which helps to increase the carrier transmission bandwidth. f TR Furthermore, to reduce the capacitance of the waveguide PD, in some embodiments, a capacitor is provided in series with the PIN diode of the waveguide PD. In at least some embodiments, to improve the responsivity of the waveguide PD with respect to photo-current conversion, the silicon waveguide is optionally configured as a multimode interference (MMI) waveguide that focuses the received light into an MMI waveguide region below the absorption region.

[0017] Figure 1 This is a simplified block diagram of an example optical communication receiver 100 according to an embodiment. The optical communication receiver 100 includes a waveguide PD having a capacitor in series with a PIN diode to increase the carrier transport bandwidth of the waveguide PD. The optical receiver 100 includes a waveguide PD 104 coupled to a signal processing circuit system 108. The signal processing circuit system 108 includes a transimpedance amplifier (TIA) 112, an analog-to-digital converter (ADC) 116, and a digital signal processing circuit system (DSP) 120 coupled in series.

[0018] Optical communication receiver 100 receives modulated light waves that transmit data via an optical communication medium such as optical fiber or free space. Waveguide PD 104 is configured to absorb light energy from the modulated light waves and convert that light energy into an analog electrical signal.

[0019] Signal processing circuitry 108 is configured to process the analog electrical signal to demodulate the data, thereby extracting and outputting the data as an output data signal. For example, TIA 112 converts the analog electrical signal output from waveguide PD 104 from a current signal to an analog voltage signal. ADC 116 converts the analog voltage signal into a digital signal, and DSP 120 processes the digital signal to demodulate the data signal, thereby extracting and outputting the data as an output data signal.

[0020] As briefly discussed above, the waveguide PD 104 includes a PIN diode and a capacitor connected in series with the PIN diode. Compared to other implementations, the thickness of the PIN diode is reduced, which helps to increase the carrier transport bandwidth of the waveguide PD. According to the embodiment, because reducing the thickness of the PIN diode increases the junction capacitance of the waveguide PD (which tends to reduce the bandwidth of the PIN diode), the capacitor connected in series with the PIN diode reduces the total capacitance of the waveguide PD (thus offsetting the negative bandwidth effect of the increased junction capacitance caused by the reduced PIN diode thickness).

[0021] Figure 2A This is a simplified block diagram (top view) of an example waveguide PD 200 according to an embodiment. According to the embodiment, the waveguide PD 200 is included... Figure 1 In waveguide PD 104. According to another embodiment, waveguide PD 200 is included in a different... Figure 1 In another suitable optical communication device, the optical receiver 100 is used. In another embodiment, the optical receiver 100 includes another suitable waveguide, different from the waveguide PD 200.

[0022] Some layers and / or components of the waveguide PD 200 are not in Figure 2AIt is shown in the middle to avoid occlusion. Figure 2A The waveguide PD 200 component exists in the middle.

[0023] Waveguide PD 200 is formed on a suitable semiconductor substrate (not shown), such as a silicon-on-insulator (SOI) substrate. Waveguide PD 200 includes an input waveguide 204 optically coupled to waveguide 208. Input waveguide 204 transmits modulated light waves (received via an optical medium such as optical fiber, free space, etc.) to waveguide 208. Input waveguide 204 and waveguide 208 comprise silicon (Si) material or other suitable materials.

[0024] An absorption region 212 is formed above waveguide 208. The absorption region 212 comprises a suitable semiconductor material, such as germanium (Ge) or other suitable materials, which is configured to absorb light energy from waveguide 208, for example, through evanescent coupling between the absorption region 212 and waveguide 208.

[0025] Metal traces 220 (sometimes referred to as “electrode 220”) are formed over the absorption region 212 and electrically coupled to the absorption region 212 through vias 224, which comprise suitable conductive materials, such as metals.

[0026] One or more metal traces 240 (sometimes referred to as “electrodes 240”) are formed over waveguide 208 and electrically coupled to waveguide 208 via vias 244, 248. The one or more electrodes 240 correspond to a reference (e.g., ground) voltage, and waveguide 208 is electrically coupled to this reference voltage vias 244, 248. Vias 244, 248 comprise a suitable conductive material, such as metal.

[0027] Electrode 220 corresponds to the electrical signal output by waveguide PD 200. According to an embodiment, electrode 220 and the one or more electrodes 240 are laterally spaced within the same layer.

[0028] Figure 2B According to the embodiments Figure 2A A simplified diagram of waveguide PD 200, showing a cross-sectional view, is provided. A doped layer 252 is formed above absorption region 212. The doped layer 252 has opposite doping (n-type doping versus p-type doping) to waveguide 208. For example, in one embodiment, doped layer 252 comprises an n-type doped material, while waveguide 208 comprises a p-type doped material. As another example, in another embodiment, doped layer 252 comprises a p-type doped material, while waveguide 208 comprises an n-type doped material. Doped layer 252 comprises Si or other suitable materials.

[0029] A doped layer 252, an absorption region 212, and a waveguide 208 form a PIN diode. In operation, light absorbed by the absorption region 212 affects the current flowing through the PIN diode. For example, in an embodiment, the PIN diode is configured to output an electrical signal in response to light energy absorbed from the waveguide 208 by the absorption region 212.

[0030] Compared to other implementations, the thickness of the PIN diode is reduced, which helps to increase the carrier transport bandwidth of the waveguide PD 200.

[0031] The doped layer 252 is electrically connected to the capacitor 256 through vias 258 and 260, which comprise a suitable conductive material, such as a metal.

[0032] In one embodiment, capacitor 256 comprises a metal-insulator-metal (MIM) capacitor. Capacitor 256 includes a lower metal layer 262, a dielectric 264, and an upper metal layer 266. In another embodiment, capacitor 256 comprises a metal-oxide-metal (MOM) capacitor. In still other embodiments, capacitor 256 comprises another suitable type of capacitor, such as a metal-oxide-semiconductor (MOS) capacitor.

[0033] According to an embodiment, capacitor 256 is electrically coupled to electrode 220 through via 224, and capacitor 256 is connected in series with PIN diode, which reduces the total capacitance of waveguide PD 200.

[0034] According to the embodiment, since reducing the thickness of the PIN diode increases the junction capacitance of the waveguide PD (which tends to reduce the bandwidth of the PIN diode), capacitor 256 is provided to reduce the total capacitance of the waveguide PD 200 (thereby offsetting the negative bandwidth effect of the increased junction capacitance caused by the reduction of the PIN diode thickness).

[0035] The waveguide PD 200 also includes one or more metal traces 268, which are electrically coupled to one or more electrodes 240 via vias 244 and 248. The one or more metal traces 268 are electrically coupled to the waveguide 208 vias 270 and 272, which are made of a suitable conductive material, such as metal.

[0036] In some embodiments, to further offset the increase in junction capacitance when the thickness of the light-absorbing region 212 is reduced, the length and / or width of the light-absorbing region 212 are reduced compared to other implementations. However, as discussed above, reducing the length and / or width of the light-absorbing region 212 tends to reduce the responsivity of the waveguide PD with respect to photocurrent conversion. In particular, because the length and / or width of the light-absorbing region 212 are reduced, there is less area of ​​the light-absorbing region 212 available for absorbing light, and / or less area available for connecting to vias 258, 260 to provide electrical coupling to capacitor 256.

[0037] Therefore, in some embodiments, waveguide 208 is configured as a multimode interference (MMI) waveguide, which is configured to provide one or more focused optical energy regions in the region of MMI waveguide 208 located below optical absorption region 212, i.e., MMI waveguide 208 overlaps with optical absorption region 212.

[0038] Figure 2C This is a simplified block diagram (top view) of waveguide PD 200 in an embodiment where waveguide 208 is configured as an MMI waveguide. Some layers and / or components of waveguide PD 200 are not shown. Figure 2C It is shown in the middle to avoid occlusion. Figure 2C The waveguide PD 200 component exists in the middle.

[0039] exist Figure 2C In the illustrated embodiment, the width w1 and / or length l1 of the absorption region 212 are reduced compared to other waveguide PD implementations. Therefore, there is less area of ​​the light absorption region 212 available for absorbing light, and / or less area available for connecting to vias 258, 260 to provide electrical coupling to capacitor 256.

[0040] MMI waveguide 208 has a width w2 and a length l2. The width w2 of MMI waveguide 208 is chosen such that light waves from input waveguide 204 form an interference pattern 280 with interference maxima regions 284. For a symmetrical MMI waveguide 208, at least some interference maxima 284 are along the region 280. Figure 2C A vertically extending axis of symmetry is formed, that is, from the input waveguide 204 to below the absorption region 212. Figure 2C The interference pattern 280 depicted is not intended to show an accurate interference pattern 280, but merely to indicate the presence of the interference pattern 280 for visualization purposes.

[0041] At least some interference maxima 284 are located in the region overlapping with the absorption region 212, i.e., below the absorption region 212. Because a high proportion of the energy in the guided light wave within the MMI waveguide 208 is concentrated (i.e., focused) in the interference maxima 284, the absorption region 212 absorbs more light energy compared to an implementation where the waveguide 208 is not configured as an MMI waveguide and the width w1 and / or length l1 of the absorption region 212 is reduced.

[0042] Figure 3 This is a flowchart of an example method 300 for manufacturing a waveguide PD according to an embodiment. According to various embodiments, method 300 is performed to manufacture... Figure 2A -B Example waveguide PD and / or Figure 2C Example waveguide PD, and for illustrative purposes, refer to Figure 2A -C is used to describe method 300. In other embodiments, method 300 is used to manufacture different... Figure 2A Another suitable photodiode for the example waveguide PD of type -C. In other embodiments, Figure 2A -B Example waveguide PD and / or Figure 2C The example waveguide PD is manufactured using a different suitable method than example method 300.

[0043] At block 304, a waveguide is fabricated on a semiconductor substrate. In an embodiment, the waveguide is configured to receive a modulated optical signal for transmitting data. In an embodiment, fabricating the waveguide at block 304 includes fabricating the waveguide on an SOI substrate. In another embodiment, fabricating the waveguide at block 304 includes fabricating the waveguide on a suitable substrate other than an SOI substrate.

[0044] According to various embodiments, fabricating the waveguide at frame 304 includes fabricating Figure 2A -B waveguide 208 and / or Figure 2C MMI waveguide 208.

[0045] At block 308, an absorption region is formed above the waveguide. In one embodiment, forming the absorption region at block 308 includes forming an absorption region comprising a Ge material. In another embodiment, forming the absorption region at block 308 includes forming an absorption region having another suitable material different from the Ge material.

[0046] According to various embodiments, manufacturing the absorption region at frame 308 includes manufacturing... Figure 2A -B absorption region 212 and / or Figure 2C The absorption region 212.

[0047] At block 312, a capacitor is fabricated to be electrically coupled in series with the absorption region, thereby reducing the capacitance of the photodiode compared to a scenario where the capacitor is omitted from the photodiode. For example, according to an embodiment, the capacitor at block 312 includes fabrication... Figure 2B The capacitor is 256.

[0048] In one embodiment, manufacturing a capacitor at block 312 includes manufacturing a MIM capacitor. In another embodiment, manufacturing a capacitor at block 312 includes manufacturing a MOM capacitor.

[0049] In another embodiment, fabricating the waveguide at block 304 includes fabricating the waveguide as an MMI waveguide. In another embodiment where the waveguide fabricated at block 304 is an MMI waveguide, fabricating the MMI waveguide includes: fabricating the MMI waveguide to be configured to generate an interference pattern having one or more local maxima located below the absorption region. In another embodiment where the waveguide fabricated at block 304 is an MMI waveguide, method 300 further includes: fabricating a first via electrically coupling the absorption region to a capacitor; and fabricating a second via electrically coupling the absorption region to a capacitor; wherein fabricating the MMI waveguide includes fabricating the MMI waveguide to be configured to generate an interference pattern having one or more local maxima located between the first and second vias.

[0050] In another embodiment, method 300 further includes: fabricating an electrode that is electrically coupled to the absorption region, such that a capacitor is electrically coupled in series between the electrode and the absorption region, thereby reducing the capacitance of the photodiode compared to a scenario where the capacitor is omitted from the photodiode. In another embodiment where method 300 includes fabricating the electrode, fabricating the capacitor at block 312 includes fabricating the capacitor above the absorption region and below the electrode.

[0051] Example 1: An optical communication receiver includes: a photodiode configured to receive a modulated optical signal for transmitting data and convert the modulated optical signal into an electrical signal. The photodiode includes: a waveguide configured to receive the modulated optical signal; an absorption region above the waveguide; and a capacitor electrically coupled in series with the absorption region, thereby reducing the capacitance of the photodiode compared to a scenario where the capacitor is omitted from the photodiode. The optical communication receiver further includes a signal processing circuit system coupled to the photodiode, the signal processing circuit system being configured to process the electrical signal to extract and output the data.

[0052] Example 2: According to the optical communication receiver of Example 1, the photodiode further includes an electrode electrically coupled to the absorption region; wherein the capacitor is electrically coupled in series between the absorption region and the electrode, thereby reducing the capacitance of the photodiode compared to a scenario where the capacitor is omitted from the photodiode.

[0053] Example 3: The optical communication receiver according to Example 2, wherein the capacitor is above the absorption region and below the electrode.

[0054] Example 4: An optical communication receiver according to any one of Examples 1-3, wherein the capacitor comprises a metal-insulator-metal (MIM) capacitor.

[0055] Example 5: An optical communication receiver according to any one of Examples 1-3, wherein the capacitor comprises a metal-oxide-metal (MOM) capacitor.

[0056] Example 6: An optical communication receiver according to any one of Examples 1-5, wherein the waveguide is configured as a multimode interference (MMI) waveguide.

[0057] Example 7: An optical communication receiver according to Example 6, wherein the MMI waveguide is configured to generate an interference pattern having one or more local maxima located below the absorption region.

[0058] Example 8: The optical communication receiver of Example 7, wherein the photodiode further includes: a first via electrically coupling the absorption region to the capacitor; and a second via electrically coupling the absorption region to the capacitor; wherein the MMI waveguide is configured to generate an interference pattern having one or more local maxima located between the first via and the second via.

[0059] Example 9: An optical communication receiver according to any one of Examples 1-8, wherein the signal processing circuit system includes: a transimpedance amplifier configured to convert the analog electrical signal output by the photodiode from an analog current signal to an analog voltage signal.

[0060] Example 10: An optical communication receiver according to any one of Examples 1-9, wherein the signal processing circuit system further includes: an analog-to-digital converter configured to convert the analog voltage signal into a digital signal; and a digital signal processing circuit system configured to process the digital signal to extract the data.

[0061] Example 11: A method of manufacturing a photodiode, comprising: manufacturing a waveguide on a semiconductor substrate, the waveguide being configured to receive a modulated optical signal transmitting data; manufacturing an absorption region above the waveguide; and manufacturing a capacitor electrically coupled in series with the absorption region, thereby reducing the capacitance of the photodiode compared to a scenario where the capacitor is omitted from the photodiode.

[0062] Example 12: The manufacturing method described in Example 11 further includes: manufacturing an electrode electrically coupled to the absorption region, such that the capacitor is electrically coupled in series between the electrode and the absorption region, thereby reducing the capacitance of the photodiode compared to a scenario where the capacitor is omitted from the photodiode.

[0063] Example 13: The manufacturing method described in Example 12, wherein manufacturing the capacitor includes: manufacturing the capacitor as being located above the absorption region and below the electrode.

[0064] Example 14: The manufacturing method of any one of Examples 11-13, wherein manufacturing the capacitor includes: manufacturing a metal-insulator-metal (MIM) capacitor.

[0065] Example 15: The manufacturing method of any one of Examples 11-13, wherein manufacturing the capacitor includes: manufacturing a metal-oxide-metal (MOM) capacitor.

[0066] Example 16: The manufacturing method of any one of Examples 11-15, wherein manufacturing the waveguide includes: manufacturing a multimode interference (MMI) waveguide.

[0067] Example 17: The manufacturing method described in Example 16, wherein manufacturing the MMI waveguide includes: manufacturing the MMI waveguide to be configured to generate an interference pattern having one or more local maxima located below the absorption region.

[0068] Example 18: The manufacturing method of Example 17 further includes: manufacturing a first via electrically coupling the absorption region to the capacitor; and manufacturing a second via electrically coupling the absorption region to the capacitor; wherein manufacturing the MMI waveguide includes manufacturing the MMI waveguide to be configured to generate an interference pattern having one or more local maxima located between the first via and the second via.

[0069] Example 19: A photodiode includes: a waveguide configured to receive the modulated optical signal; an absorption region above the waveguide; and a capacitor electrically coupled in series with the absorption region, thereby reducing the capacitance of the photodiode compared to a scenario where the capacitor is omitted from the photodiode.

[0070] Example 20: The photodiode of Example 19, wherein the photodiode further includes: an electrode electrically coupled to the absorption region; wherein the capacitor is electrically coupled in series between the absorption region and the electrode, thereby reducing the capacitance of the photodiode compared to a scenario where the capacitor is omitted from the photodiode.

[0071] Example 21: The photodiode of Example 20, wherein the capacitor is above the absorption region and below the electrode.

[0072] Example 22: A photodiode according to any one of Examples 19-21, wherein the capacitor comprises a metal-insulator-metal (MIM) capacitor.

[0073] Example 23: A photodiode according to any one of Examples 19-21, wherein the capacitor comprises a metal-oxide-metal (MOM) capacitor.

[0074] Example 24: A photodiode according to any one of Examples 19-23, wherein the waveguide is configured as a multimode interference (MMI) waveguide that generates an interference pattern having one or more local maxima located below the absorption region.

[0075] Example 25: The photodiode of Example 24, wherein the MMI waveguide is configured to generate an interference pattern having one or more local maxima located below the absorption region.

[0076] Example 26: The photodiode of Example 25, wherein the photodiode further includes: a first via electrically coupling the absorption region to the capacitor; and a second via electrically coupling the absorption region to the capacitor; wherein the MMI waveguide is configured to generate an interference pattern having one or more local maxima located between the first via and the second via.

[0077] Example 27: A photodiode according to any one of Examples 19-26, wherein the photodiode is configured to convert a modulated optical signal for transmitting data into an electrical signal.

[0078] Although the invention has been described with reference to specific examples, these examples are intended to be illustrative only and not limiting of the invention, and changes, additions and / or deletions may be made to the disclosed embodiments without departing from the scope of the invention.

Claims

1. An optical communication receiver, comprising: A photodiode, configured to receive a modulated optical signal and convert the modulated optical signal into an electrical signal, wherein the modulated optical signal transmits data, the photodiode comprising: A waveguide is configured to receive the modulated optical signal. Absorption region, above the waveguide, and A capacitor, electrically coupled in series with the absorption region, thereby reducing the capacitance of the photodiode compared to a scenario where the capacitor is omitted from the photodiode; and A signal processing circuit system, coupled to the photodiode, is configured to process the electrical signal to extract and output the data.

2. The optical communication receiver according to claim 1, wherein the photodiode further comprises: Electrodes, electrically coupled to the absorption region; The capacitor is connected in series between the absorption region and the electrode, thereby reducing the capacitance of the photodiode compared to a scenario where the capacitor is omitted from the photodiode.

3. The optical communication receiver of claim 2, wherein the capacitor is above the absorption region and below the electrode.

4. The optical communication receiver according to claim 1, wherein the capacitor comprises a metal-insulator-metal (MIM) capacitor.

5. The optical communication receiver according to claim 1, wherein the capacitor comprises a metal-oxide-metal (MOM) capacitor.

6. The optical communication receiver of claim 1, wherein the waveguide is configured as a multimode interference (MMI) waveguide.

7. The optical communication receiver of claim 6, wherein the MMI waveguide is configured to generate an interference pattern having one or more local maxima located below the absorption region.

8. The optical communication receiver according to claim 7, wherein the photodiode further comprises: A first via allows the absorption region to be electrically coupled to the capacitor; as well as A second via allows the absorption region to be electrically coupled to the capacitor; The MMI waveguide is configured to generate an interference pattern having one or more local maxima between the first via and the second via.

9. The optical communication receiver according to claim 1, wherein the signal processing circuit system comprises: A transimpedance amplifier is configured to convert the analog electrical signal output by the photodiode from an analog current signal to an analog voltage signal.

10. The optical communication receiver according to claim 1, wherein the signal processing circuit system further comprises: An analog-to-digital converter is configured to convert the analog voltage signal into a digital signal; as well as A digital signal processing circuit system is configured to process the digital signal to extract the data.

11. A method for manufacturing a photodiode, the method comprising: A waveguide is fabricated on a semiconductor substrate, the waveguide being configured to receive a modulated optical signal that transmits data; An absorption region is created above the waveguide; as well as A capacitor is manufactured that is electrically coupled in series with the absorption region, thereby reducing the capacitance of the photodiode compared to a scenario where the capacitor is omitted from the photodiode.

12. The method for manufacturing according to claim 11, further comprising: The electrodes are fabricated to be electrically coupled to the absorption region, such that the capacitor is electrically coupled in series between the electrodes and the absorption region, thereby reducing the capacitance of the photodiode compared to a scenario where the capacitor is omitted from the photodiode.

13. The method of manufacturing according to claim 12, wherein manufacturing the capacitor comprises: The capacitor is manufactured above the absorption region and below the electrode.

14. The method of manufacturing according to claim 11, wherein manufacturing the capacitor comprises: Manufacturing metal-insulator-metal (MIM) capacitors.

15. The method of manufacturing according to claim 11, wherein manufacturing the capacitor comprises: Manufacturing metal-oxide-metal (MOM) capacitors.

16. The method of manufacturing according to claim 11, wherein manufacturing the waveguide comprises: Fabrication of multimode interference (MMI) waveguides.

17. The method of manufacturing according to claim 16, wherein manufacturing the MMI waveguide comprises: The MMI waveguide is fabricated to generate an interference pattern having one or more local maxima located below the absorption region.

18. The method for manufacturing according to claim 17, further comprising: A first via is fabricated, which electrically couples the absorption region to the capacitor. as well as A second via is fabricated, which electrically couples the absorption region to the capacitor; Manufacturing the MMI waveguide includes manufacturing the MMI waveguide to be configured to generate an interference pattern: the interference pattern has one or more local maxima located between the first via and the second via.

19. A photodiode for converting a modulated optical signal into an electrical signal, wherein the modulated optical signal transmits data, the photodiode comprising: A waveguide is configured to receive the modulated optical signal; Absorption region, above the waveguide; as well as A capacitor is electrically coupled in series with the absorption region, thereby reducing the capacitance of the photodiode compared to a scenario where the capacitor is omitted from the photodiode.

20. The photodiode of claim 19, wherein the photodiode further comprises: Electrodes, electrically coupled to the absorption region; The capacitor is connected in series between the absorption region and the electrode, thereby reducing the capacitance of the photodiode compared to a scenario where the capacitor is omitted from the photodiode.

21. The photodiode of claim 20, wherein the capacitor is above the absorption region and below the electrode.

22. The photodiode of claim 19, wherein the waveguide is configured as a multimode interference (MMI) waveguide that generates an interference pattern having one or more local maxima located below the absorption region.

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