Photodetector and method for manufactring photodetector

Abstract

The present disclosure relates to the technical field of chip detection, and in particular to a photodetector and a method for manufacturing the photodetector. The photodetector comprises: an epitaxial layer, a first avalanche diode, a second avalanche diode, a waveguide isolation layer, a first wedge-shaped groove and a second wedge-shaped groove; and a first strip waveguide, a second strip waveguide and a ring waveguide, all of which are formed on the side of the waveguide isolation layer that is away from the epitaxial layer, wherein the first strip waveguide is located at an input end of the ring waveguide, and the second strip waveguide is located at an output end of the ring waveguide; part of the first strip waveguide passes through the first wedge-shaped groove, and part of the second strip waveguide passes through the second wedge-shaped groove. The technical solution of the present disclosure can realize the miniaturization of a ring resonator detector while facilitating cost reduction in design.

Description

Photodetectors and their fabrication methods Technical Field

[0001] This disclosure relates to the field of chip detection technology, and in particular to a photodetector and a method for fabricating the photodetector. Background Technology

[0002] Currently, ring resonant cavity detectors have promising applications in the fields of chemical composition and biological detection, such as food detection, virus testing, health monitoring, and environmental monitoring, with advantages such as high sensitivity and the ability to perform multi-substance inspection using arrays.

[0003] In related technologies, the ring resonator and photodiode in a ring resonator detector need to be connected by tapered optical fiber, which makes it impossible to miniaturize the ring resonator detector. At the same time, the high price of tapered optical fiber increases the design cost of the ring resonator detector. Summary of the Invention

[0004] To solve the above-mentioned technical problems, or at least partially solve them, this disclosure provides a photodetector and a method for fabricating the photodetector, which enables miniaturization of the ring resonant cavity detector and helps reduce design costs.

[0005] In a first aspect, this disclosure provides a photodetector, comprising:

[0006] An epitaxial layer and a first avalanche diode and a second avalanche diode formed through the epitaxial layer, wherein the first avalanche diode is located in a first through groove formed in the epitaxial layer and the second avalanche diode is located in a second through groove formed in the epitaxial layer;

[0007] A waveguide isolation layer is located on one side of the epitaxial layer, and the light receiving surfaces of the first avalanche diode and the second avalanche diode both face the waveguide isolation layer; the waveguide isolation layer forms a through-hole first wedge-shaped groove at the position corresponding to the position of the light receiving surface of the first avalanche diode, and the waveguide isolation layer forms a through-hole second wedge-shaped groove at the position corresponding to the position of the light receiving surface of the second avalanche diode.

[0008] The first strip waveguide, the second strip waveguide, and the ring waveguide are all formed on the side of the waveguide isolation layer away from the epitaxial layer; the first strip waveguide is located at the input end of the ring waveguide, and the second strip waveguide is located at the output end of the ring waveguide;

[0009] Part of the first strip waveguide passes through the first wedge-shaped groove, and part of the second strip waveguide passes through the second wedge-shaped groove.

[0010] In some embodiments, the first strip waveguide includes a first waveguide portion, which passes through the first wedge-shaped groove;

[0011] The second strip waveguide includes a second waveguide portion, which passes through the second wedge-shaped groove.

[0012] In some embodiments, the first strip waveguide further includes a third waveguide portion connected to the first waveguide portion;

[0013] The second strip waveguide also includes a fourth waveguide section connected to the second waveguide section;

[0014] The third waveguide section and the fourth waveguide section are arranged parallel to the ring waveguide.

[0015] In some embodiments, the photodetector further includes:

[0016] A first protective layer is located between the epitaxial layer and the waveguide isolation layer;

[0017] A portion of the first strip waveguide is in contact with the first protective layer, and a portion of the second strip waveguide is in contact with the first protective layer.

[0018] In some embodiments, the thickness of the first protective layer is between 5 nm and 10 nm.

[0019] In some embodiments, the materials forming the first strip waveguide, the second strip waveguide, and the ring waveguide include silicon oxynitride.

[0020] In some embodiments, the photodetector further includes:

[0021] A second protective layer covers the side of the waveguide isolation layer where the annular waveguide is formed and exposes the annular waveguide.

[0022] In some embodiments, the photodetector further includes:

[0023] A light source is connected to the input end of the first strip waveguide.

[0024] Secondly, this disclosure also provides a method for fabricating a photodetector, comprising:

[0025] An epitaxial layer is provided and a first avalanche diode and a second avalanche diode are formed through the epitaxial layer, wherein the first avalanche diode is located in a first through groove formed in the epitaxial layer and the second avalanche diode is located in a second through groove formed in the epitaxial layer;

[0026] A waveguide isolation layer is formed on one side of the epitaxial layer, and the light receiving surfaces of the first avalanche diode and the second avalanche diode both face the waveguide isolation layer;

[0027] A first wedge-shaped groove is formed through the waveguide isolation layer at the position corresponding to the light receiving surface of the first avalanche diode, and a second wedge-shaped groove is formed through the waveguide isolation layer at the position corresponding to the light receiving surface of the second avalanche diode.

[0028] A first strip waveguide, a second strip waveguide, and a ring waveguide are formed on the side of the waveguide isolation layer away from the epitaxial layer. The first strip waveguide is located at the input end of the ring waveguide, and the second strip waveguide is located at the output end of the ring waveguide. A portion of the first strip waveguide passes through the first wedge-shaped groove, and a portion of the second strip waveguide passes through the second wedge-shaped groove.

[0029] In some embodiments, before a waveguide isolation layer is formed on one side of the epitaxial layer, the method for fabricating the photodetector further includes:

[0030] A first protective layer is formed on one side of the epitaxial layer, and the first protective layer is located between the epitaxial layer and the waveguide isolation layer.

[0031] The photodetector provided in this embodiment includes: an epitaxial layer and a first avalanche diode and a second avalanche diode formed through the epitaxial layer, wherein the first avalanche diode is located in a first through-groove formed in the epitaxial layer, and the second avalanche diode is located in a second through-groove formed in the epitaxial layer; a waveguide isolation layer located on one side of the epitaxial layer, wherein the light-receiving surfaces of the first avalanche diode and the second avalanche diode both face the waveguide isolation layer; a through-groove first wedge-shaped groove is formed in the waveguide isolation layer corresponding to the position of the light-receiving surface of the first avalanche diode, and a through-groove second wedge-shaped groove is formed in the waveguide isolation layer corresponding to the position of the light-receiving surface of the second avalanche diode; a first strip waveguide, a second strip waveguide, and a ring waveguide are all formed on the side of the waveguide isolation layer away from the epitaxial layer; the first strip waveguide is located at the input end of the ring waveguide, and the second strip waveguide is located at the output end of the ring waveguide; wherein a portion of the first strip waveguide passes through the first wedge-shaped groove, and a portion of the second strip waveguide passes through the second wedge-shaped groove. Therefore, a ring resonant cavity detector is fabricated by forming a first avalanche diode and a second avalanche diode on the epitaxial layer, and then integrating a first strip waveguide, a second strip waveguide, and a ring waveguide (i.e., a ring resonant cavity) on the side where the light receiving surfaces of the first and second avalanche diodes are located. Neither the first nor the second avalanche diode needs to be connected to the ring waveguide using tapered optical fiber, thus enabling miniaturization of the ring resonant cavity detector and avoiding the increased design cost caused by the use of tapered optical fiber in related technologies. Attached Figure Description

[0032] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0033] To more clearly illustrate the technical solutions in the embodiments or related technologies of this disclosure, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0034] Figure 1 is a schematic diagram of the structure of a photodetector provided in an embodiment of this disclosure;

[0035] Figure 2 is a schematic diagram of another photodetector provided in an embodiment of this disclosure;

[0036] Figure 3 is a schematic diagram of the structure of another photodetector provided in an embodiment of this disclosure;

[0037] Figure 4 is a schematic diagram of transmission loss and detection efficiency provided in an embodiment of this disclosure;

[0038] Figure 5 is a schematic diagram of the structure of another photodetector provided in an embodiment of this disclosure;

[0039] Figure 6 is a schematic diagram of the structure of another photodetector provided in an embodiment of this disclosure;

[0040] Figure 7 is a schematic diagram of the structure of another photodetector provided in an embodiment of this disclosure;

[0041] Figure 8 is a schematic diagram of the structure of another photodetector provided in an embodiment of this disclosure;

[0042] Figure 9 is a schematic diagram of the structure of another photodetector provided in an embodiment of this disclosure;

[0043] Figure 10 is a schematic flowchart of a method for fabricating a photodetector according to an embodiment of this disclosure. Detailed Implementation

[0044] To better understand the above-mentioned objectives, features, and advantages of this disclosure, the solutions disclosed herein will be further described below. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0045] Numerous specific details are set forth in the following description in order to provide a full understanding of this disclosure, but this disclosure may also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only some, and not all, of the embodiments of this disclosure.

[0046] The photodetector and its fabrication method provided in the embodiments of this disclosure will be described exemplarily below with reference to the accompanying drawings.

[0047] Figure 1 is a schematic diagram of a photodetector provided in an embodiment of this disclosure, Figure 2 is a schematic diagram of another photodetector provided in an embodiment of this disclosure, and Figure 3 is a schematic diagram of yet another photodetector provided in an embodiment of this disclosure. Figure 1 is a top view, Figure 2 is a cross-sectional view along AA' in Figure 1, and Figure 3 is a cross-sectional view along BB' in Figure 1.

[0048] Referring to Figures 1 to 3, the photodetector includes: an epitaxial layer 11 and a first avalanche diode 121 and a second avalanche diode 122 formed through the epitaxial layer 11. The first avalanche diode 121 is located in a first through-groove formed in the epitaxial layer 11, and the second avalanche diode 122 is located in a second through-groove formed in the epitaxial layer 11; a waveguide isolation layer 13 is located on one side of the epitaxial layer 11, and the light-receiving surfaces of the first avalanche diode 121 and the second avalanche diode 122 both face the waveguide isolation layer 13; the waveguide isolation layer 13 corresponds to the location of the light-receiving surface of the first avalanche diode 121. A first wedge-shaped groove 141 is formed through the waveguide isolation layer 13, and a second wedge-shaped groove 142 is formed through the waveguide isolation layer 13 at the location of the light receiving surface of the second avalanche diode 122. The first strip waveguide 15, the second strip waveguide 16, and the ring waveguide 17 are all formed on the side of the waveguide isolation layer 13 away from the epitaxial layer 11. The first strip waveguide 15 is located at the input end of the ring waveguide 17, and the second strip waveguide 16 is located at the output end of the ring waveguide 17. Among them, part of the first strip waveguide 15 passes through the first wedge-shaped groove 141, and part of the second strip waveguide 16 passes through the second wedge-shaped groove 142.

[0049] An avalanche diode is a photodiode that operates in Geiger mode (operating voltage greater than breakdown voltage). Due to its advantages such as high detection efficiency, low power consumption, and fast response speed, it is widely used in spectroscopy, quantum communication, and 3D imaging. The working principle of an avalanche diode is that in Geiger mode, when the diode absorbs photons, electron-hole pairs are generated in the avalanche region. Under the influence of a strong electric field, an avalanche multiplication effect occurs, forming an avalanche current.

[0050] In this embodiment, a first avalanche diode 121 and a second avalanche diode 122 are fabricated on the epitaxial layer 11 using processes such as photolithography, doping, and thinning. The light-receiving surfaces (top surfaces) of both the first avalanche diode 121 and the second avalanche diode 122 face the waveguide isolation layer 13.

[0051] Specifically, the first strip waveguide 15 is used to receive the optical signal output by the light source 21, for example, as described below. When the resonance condition is met, the optical signal in the first strip waveguide 15 is coupled into the ring waveguide 17, i.e., the ring resonant cavity, and then the optical signal is coupled into the second strip waveguide 16.

[0052] Part of the second strip waveguide 16 passes through the second wedge-shaped groove 142. For example, as shown in FIG3, the second waveguide portion 02 of the second strip waveguide 16 passes through the second wedge-shaped groove 142. Thus, when the resonance condition is met, the optical signal can pass through the second wedge-shaped groove 142, and photons can be received by the light-receiving surface of the second avalanche diode 122. Electron-hole pairs are generated in the avalanche region, and under the action of a strong electric field, an avalanche multiplication effect occurs, forming an avalanche current, thereby enabling the second avalanche diode 122 to detect the resonant wavelength.

[0053] Specifically, when the resonance condition is not met, the optical signal in the first strip waveguide 15 is not coupled to the ring waveguide 17, i.e., the ring resonant cavity. A portion of the first strip waveguide 15 passes through the first wedge-shaped groove 141. For example, as shown in FIG2, the first waveguide portion 01 in the first strip waveguide 15 passes through the first wedge-shaped groove 141. Thus, even when the resonance condition is not met, the optical signal can pass through the first wedge-shaped groove 141, and photons can be received by the light-receiving surface of the first avalanche diode 122, generating electron-hole pairs in the avalanche region. Under the action of a strong electric field, an avalanche multiplication effect occurs, forming an avalanche current, thereby enabling the first avalanche diode 122 to detect the non-resonant wavelength.

[0054] For example, Figure 4 is a schematic diagram of transmission loss and detection efficiency provided by an embodiment of this disclosure. As shown in Figure 4, when resonance occurs, the resonant wavelength is detected and received by the second avalanche diode 122 in Figure 3; when no resonance occurs, the non-resonant wavelength is detected and received by the first avalanche diode 121 in Figure 2.

[0055] The waveguide isolation layer 13 prevents the optical signal from being absorbed by the epitaxial layer 11 as it propagates along the vertical direction YY', thereby reducing the transmission loss of the optical signal in the first strip waveguide 15, the second strip waveguide 16, and the ring waveguide 17. For example, the thickness of the waveguide isolation layer 13 in the vertical direction YY' can be set to 1 μm.

[0056] Furthermore, a through-hole first wedge-shaped groove 141 is formed at the location of the light-receiving surface corresponding to the waveguide isolation layer 13. When the resonance condition is not met, when the optical signal is transmitted to the first wedge-shaped groove 141, it is equivalent to the optical signal passing through the light-receiving surface of the first avalanche diode 121. This facilitates the light-receiving surface of the first avalanche diode 121 in receiving photons, thereby improving the reliability and sensitivity of the photodetector in detecting optical signals. Similarly, a through-hole second wedge-shaped groove 142 is formed at the location of the light-receiving surface corresponding to the waveguide isolation layer 13. When the resonance condition is met, when the optical signal is transmitted to the second wedge-shaped groove 142, it is equivalent to the optical signal passing through the light-receiving surface of the second avalanche diode 122. This facilitates the light-receiving surface of the second avalanche diode 122 in receiving photons, thereby improving the reliability and sensitivity of the photodetector in detecting optical signals.

[0057] Therefore, by setting the waveguide isolation layer 13 and forming a through wedge-shaped groove at the position of the light receiving surface corresponding to the waveguide isolation layer 13, it is beneficial to reduce the optical signal transmission loss and improve the reliability and sensitivity of the photodetector.

[0058] In related technologies, the ring resonator and photodiode in a ring resonator detector need to be connected via tapered optical fiber, resulting in a large size of the ring resonator detector and preventing its miniaturization. Furthermore, the high cost of tapered optical fiber increases the design cost of the ring resonator detector.

[0059] Compared to related technologies, this embodiment of the present disclosure forms a first avalanche diode 121 and a second avalanche diode 122 on the epitaxial layer 11, and then integrates a first strip waveguide 15, a second strip waveguide 16, and a ring waveguide 17 (i.e., a ring resonant cavity) on the side where the light receiving surfaces of the first and second avalanche diodes 121 and 122 are located, thereby fabricating a ring resonant cavity detector. Neither the first avalanche diode 121 nor the second avalanche diode 122 needs to be connected to the ring waveguide 17 using tapered optical fiber, thus enabling miniaturization of the ring resonant cavity detector and avoiding the increased design cost of the ring resonant cavity detector caused by the use of tapered optical fiber in related technologies. Furthermore, in this embodiment, the avalanche diodes and the ring resonant cavity are completely independent, so the performance parameters of the resonant cavity are not affected while the ring resonant cavity detector is integrated.

[0060] The photodetector provided in this embodiment includes: an epitaxial layer and a first avalanche diode and a second avalanche diode formed through the epitaxial layer, wherein the first avalanche diode is located in a first through-groove formed in the epitaxial layer, and the second avalanche diode is located in a second through-groove formed in the epitaxial layer; a waveguide isolation layer located on one side of the epitaxial layer, wherein the light-receiving surfaces of the first avalanche diode and the second avalanche diode both face the waveguide isolation layer; a through-groove first wedge-shaped groove is formed in the waveguide isolation layer corresponding to the position of the light-receiving surface of the first avalanche diode, and a through-groove second wedge-shaped groove is formed in the waveguide isolation layer corresponding to the position of the light-receiving surface of the second avalanche diode; a first strip waveguide, a second strip waveguide, and a ring waveguide are all formed on the side of the waveguide isolation layer away from the epitaxial layer; the first strip waveguide is located at the input end of the ring waveguide, and the second strip waveguide is located at the output end of the ring waveguide; wherein a portion of the first strip waveguide passes through the first wedge-shaped groove, and a portion of the second strip waveguide passes through the second wedge-shaped groove. Therefore, a ring resonant cavity detector is fabricated by forming a first avalanche diode and a second avalanche diode on the epitaxial layer, and then integrating a first strip waveguide, a second strip waveguide, and a ring waveguide (i.e., a ring resonant cavity) on the side where the light receiving surfaces of the first and second avalanche diodes are located. Neither the first nor the second avalanche diode needs to be connected to the ring waveguide using tapered optical fiber, thus enabling miniaturization of the ring resonant cavity detector and avoiding the increased design cost caused by the use of tapered optical fiber in related technologies.

[0061] For the aforementioned ring waveguide, i.e., ring resonant cavity, if the wavelength meets the condition... Resonance will occur. The length of the ring resonator. The resonant wavelength, The effective refractive index of the ring resonant cavity causes a peak in the detection efficiency curve of the avalanche diode at the resonant wavelength. This peak can be used to determine the corresponding resonant wavelength. Since the resonant wavelength is directly related to the effective refractive index of the ring resonant cavity, changes in the ambient temperature and external refractive index will cause a shift in the resonant wavelength. By using the change in the resonant wavelength detected by the avalanche diode, the temperature and refractive index of the surrounding environment can be determined. The relationship between the effective refractive index, temperature, and resonant wavelength is as follows:

[0062]

[0063] in, is the relative permittivity. The relationship between the resonant wavelength and temperature is as follows:

[0064]

[0065] in, The refractive index of the epitaxial layer is... Standard temperature value, The resonant wavelength corresponding to the standard temperature value. Assuming the temperature change value, the resonant wavelength changes linearly with temperature. By simply measuring the resonant wavelength within a temperature range near a standard temperature, a temperature-wavelength curve can be obtained. Subsequently, using an avalanche diode, the resonant wavelength at different temperatures can be obtained, and the corresponding temperatures can be directly found on the curve. The relationship between the resonant wavelength and the ambient refractive index is as follows:

[0066]

[0067] Similarly, the relationship between the effective refractive index and the relative permittivity can be obtained by testing the standard resonant wavelength, and this relationship can be used to subsequently test the relationship between the refractive index change and the resonant wavelength shift.

[0068] In some embodiments, referring to Figures 1 to 3, the first strip waveguide 15 further includes a third waveguide section 03 connected to the first waveguide section 01; the second strip waveguide 16 further includes a fourth waveguide section 04 connected to the second waveguide section 02; the third waveguide section 03 and the fourth waveguide section 04 are arranged parallel to the ring waveguide.

[0069] Specifically, the input end of the ring waveguide 17 is arranged parallel to the third waveguide section 03, and the output end of the ring waveguide 17 is arranged parallel to the fourth waveguide section 04. The input and output ends of the ring waveguide 17 are opposite sides of the ring waveguide 17.

[0070] In some embodiments, as shown in FIG1, the third waveguide 03 and the fourth waveguide 04 are equidistant from the ring waveguide 17 and are located between 0 and 1 μm.

[0071] Specifically, the third waveguide section 03 is located at the input end of the ring waveguide 17, and the distance between the third waveguide section 03 and the ring waveguide 17 is between 0 and 1 μm. This allows the first strip waveguide 15 to be close to the input end of the ring waveguide 17, which is beneficial for the optical signal in the first strip waveguide 15 to couple into the ring waveguide 17. Thus, by setting the distance between the third waveguide section 03 and the ring waveguide 17 to between 0 and 1 μm, while maintaining a gap between the first strip waveguide 15 and the ring waveguide 17, it is beneficial for the optical signal in the first strip waveguide 15 to couple into the ring waveguide 17.

[0072] Specifically, the fourth waveguide section 04 is located at the output end of the ring waveguide 17, and the distance between the fourth waveguide section 04 and the ring waveguide 17 is between 0 and 1 μm. This allows the second waveguide section 162 to be close to the output end of the ring waveguide 17, which is beneficial for the optical signal in the ring waveguide 17 to be coupled into the second strip waveguide 16. Thus, by setting the distance between the fourth waveguide section 04 and the ring waveguide 17 to be between 0 and 1 μm, while maintaining a gap between the second strip waveguide 16 and the ring waveguide 17, it is beneficial for the optical signal in the ring waveguide 17 to be coupled into the second waveguide section 162.

[0073] In some embodiments, FIG5 is a schematic diagram of the structure of another photodetector provided in the present disclosure, and FIG6 is a schematic diagram of the structure of another photodetector provided in the present disclosure. As shown in FIG5 or FIG6, the photodetector may further include: a first protective layer 18, the first protective layer 18 being located between the epitaxial layer 11 and the waveguide isolation layer 13; a portion of the first strip waveguide 15 contacting the first protective layer 18, and a portion of the second strip waveguide 16 contacting the first protective layer 18.

[0074] Specifically, by forming a first protective layer 18 between the epitaxial layer 11 and the waveguide isolation layer 13, the first protective layer 18 can serve as an etching stop layer when etching the waveguide isolation layer 13 to form the first wedge-shaped groove 141 and the second wedge-shaped groove 142, which helps to avoid etching damage to the first avalanche diode 121 and the second avalanche diode 122 due to etching the waveguide isolation layer 13.

[0075] Furthermore, when the first waveguide portion 01 passes through the first wedge-shaped groove 141, it sequentially passes through one side slope, the bottom end, and the other side slope of the first wedge-shaped groove 141. When the first waveguide portion 01 passes through the bottom end of the first wedge-shaped groove 141, it directly contacts the first protective layer 18. Similarly, when the second waveguide portion 02 passes through the second wedge-shaped groove 142, it sequentially passes through one side slope, the bottom end, and the other side slope of the second wedge-shaped groove 142. When the second waveguide portion 02 passes through the bottom end of the second wedge-shaped groove 142, it directly contacts the first protective layer 18.

[0076] In some embodiments, as shown in FIG5 or FIG6, the thickness of the first protective layer is between 5nm and 10nm.

[0077] Specifically, the thickness of the first protective layer 18 is set between 5nm and 10nm. When the first waveguide 01 passes the bottom end of the first wedge-shaped groove 141, the first waveguide 01 is brought close to the light receiving surface of the first avalanche diode 121, which is beneficial for the light receiving surface of the first avalanche diode 121 to receive photons, thereby improving the reliability and sensitivity of the photodetector.

[0078] Similarly, when the second waveguide 02 passes the bottom end of the second wedge-shaped groove 142, the second waveguide 02 is brought close to the light receiving surface of the second avalanche diode 122, which is beneficial for the light receiving surface of the second avalanche diode 122 to receive photons, thereby improving the reliability and sensitivity of the photodetector.

[0079] In conjunction with the above, the first protective layer 18 serves as an etch stop layer, and its thickness is between 5nm and 10nm to sufficiently avoid etch damage to the first avalanche diode 121 and the second avalanche diode 122 caused by etching the waveguide isolation layer 13.

[0080] For example, the material forming the first strip waveguide, the second strip waveguide, and the ring waveguide may be silicon oxynitride. In some embodiments, the material forming the first strip waveguide, the second strip waveguide, and the ring waveguide may also include other materials well known to those skilled in the art, to achieve optical signal coupling from the first strip waveguide to the ring waveguide, and optical signal coupling from the ring waveguide to the second strip waveguide.

[0081] In some embodiments, FIG7 is a schematic diagram of the structure of another photodetector provided in the present disclosure, FIG8 is a schematic diagram of the structure of another photodetector provided in the present disclosure, and FIG9 is a schematic diagram of the structure of another photodetector provided in the present disclosure. FIG9 is a top view, and FIG7 and FIG8 are cross-sectional views.

[0082] As shown in Figures 7-9, the photodetector also includes a second protective layer 19, which covers the side of the waveguide isolation layer 13 where the annular waveguide 17 is formed and exposes the annular waveguide 17.

[0083] For example, the second protective layer 19 may be a protective layer formed of silicon dioxide, used to protect the first strip waveguide 15 and the second strip waveguide 16. The annular waveguide 17 is exposed to facilitate changes in the external environment of the annular waveguide 17, thereby changing the external refractive index of the annular waveguide 17.

[0084] In some embodiments, as shown in FIG1, the photodetector further includes a light source 21, which is connected to the input terminal of the first strip waveguide 15. Specifically, the light source, such as a laser, is used to emit an optical signal, which is transmitted to the first strip waveguide 15 through the input terminal of the first strip waveguide 15.

[0085] Therefore, this embodiment integrates a waveguide on the surface of the avalanche diode, facilitating the evanescent wave to allow photons to enter the photosensitive region and trigger avalanche breakdown. This achieves the integration of the resonant cavity and the single-photon detector, enabling the design of a miniaturized ring resonant cavity detector. The resonant wavelength is directly obtained through the avalanche diode without the need for additional detectors, allowing for the miniaturization of large-scale detector arrays. Furthermore, the elimination of the need for tapered optical fibers to connect the photodetector reduces costs. Simultaneously, the charge carriers generated by photons entering the avalanche diode from the waveguide converge towards the central avalanche region under the influence of the electric field, triggering avalanche breakdown, thus ensuring the reliability and sensitivity of the designed ring resonant cavity detector.

[0086] It should be noted that the embodiments of this disclosure can also improve the sensitivity of the detector and enable the detection of specific substances by depositing chemical substances on the surface of the ring waveguide, i.e., the ring resonant cavity.

[0087] Based on the above embodiments, this disclosure also provides a method for fabricating a photodetector. Figure 10 is a schematic flowchart of a method for fabricating a photodetector provided in an embodiment of this disclosure. As shown in Figure 10, the fabrication method includes the following steps:

[0088] S601. An epitaxial layer is provided and a first avalanche diode and a second avalanche diode are formed through the epitaxial layer. The first avalanche diode is located in a first through groove formed in the epitaxial layer, and the second avalanche diode is located in a second through groove formed in the epitaxial layer.

[0089] Specifically, as shown in Figures 2 and 3, an epitaxial layer 11 is provided, on which a first avalanche diode 121 and a second avalanche diode 122 are fabricated, for example, by photolithography, doping, and thinning processes. Specific fabrication processes can employ techniques well-known in the art, and will not be elaborated upon here.

[0090] S602. A waveguide isolation layer is formed on one side of the epitaxial layer, and the light receiving surfaces of the first avalanche diode and the second avalanche diode both face the waveguide isolation layer.

[0091] Specifically, as shown in Figures 2 and 3, a waveguide isolation layer is formed on one side of the top of the epitaxial layer. Specifically, the waveguide isolation layer 13 can prevent the optical signal from being absorbed by the epitaxial layer 11 when it is transmitted along the vertical direction YY', which helps to reduce the transmission loss of the optical signal in the first strip waveguide 15, the second strip waveguide 16 and the ring waveguide 17.

[0092] S603. A through-hole first wedge-shaped groove is formed at the position of the light receiving surface of the first avalanche diode in the waveguide isolation layer, and a through-hole second wedge-shaped groove is formed at the position of the light receiving surface of the second avalanche diode.

[0093] Specifically, as shown in Figure 2, an etching region is defined for the waveguide isolation layer 13, and a first wedge-shaped groove 141 is formed by wet etching. The first wedge-shaped groove 141 corresponds to the location of the light receiving surface of the first avalanche diode 121.

[0094] Specifically, as shown in Figure 3, an etching region is defined for the waveguide isolation layer 13, and a second wedge-shaped groove 142 is formed by wet etching. The second wedge-shaped groove 142 corresponds to the location of the light receiving surface of the second avalanche diode 122.

[0095] S604. A first strip waveguide, a second strip waveguide, and a ring waveguide are formed on the side of the waveguide isolation layer away from the epitaxial layer. The first strip waveguide is located at the input end of the ring waveguide, and the second strip waveguide is located at the output end of the ring waveguide. Part of the first strip waveguide passes through the first wedge-shaped groove, and part of the second strip waveguide passes through the second wedge-shaped groove.

[0096] Specifically, as shown in Figures 2 and 3, a layer of silicon oxynitride is deposited on the side of the waveguide isolation layer 13 away from the epitaxial layer 11, and then the first strip waveguide 15, the second strip waveguide 16 and the ring waveguide 17 are formed by photolithography and dry etching.

[0097] The first strip waveguide 15 is located at the input end of the ring waveguide 17, and the second strip waveguide 16 is located at the output end of the ring waveguide 17; part of the first strip waveguide 15, i.e. the first waveguide section 01, passes through the first wedge-shaped groove 141, and part of the second strip waveguide 16, i.e. the second waveguide section 02, passes through the second wedge-shaped groove 142.

[0098] In some embodiments, before forming a waveguide isolation layer on one side of the epitaxial layer, the method for fabricating the photodetector further includes:

[0099] A first protective layer is formed on one side of the epitaxial layer, and the first protective layer is located between the epitaxial layer and the waveguide isolation layer.

[0100] Specifically, as shown in Figure 5 or Figure 6, a first protective layer is formed on one side of the epitaxial layer. When etching the waveguide isolation layer 13 to form the first wedge-shaped groove 141 and the second wedge-shaped groove 142, the first protective layer 18 can serve as an etching stop layer, which helps to avoid etching damage to the avalanche diode caused by etching the waveguide isolation layer 13.

[0101] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0102] The above are merely specific embodiments of this disclosure, enabling those skilled in the art to understand or implement this disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not to be limited to these embodiments, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A photodetector, comprising: The application relates to a light-emitting device, which comprises: an epitaxial layer and a first avalanche diode and a second avalanche diode formed by the epitaxial layer, the first avalanche diode is located in a first through groove formed by the epitaxial layer, and the second avalanche diode is located in a second through groove formed by the epitaxial layer; a waveguide isolation layer located on one side of the epitaxial layer, the light receiving surfaces of the first avalanche diode and the second avalanche diode are both directed towards the waveguide isolation layer; the waveguide isolation layer is formed with a first wedge-shaped groove penetrating the position where the light receiving surface of the first avalanche diode is located, and is formed with a second wedge-shaped groove penetrating the position where the light receiving surface of the second avalanche diode is located; a first strip waveguide, a second strip waveguide and a ring waveguide are all formed on the side of the waveguide isolation layer away from the epitaxial layer; the first strip waveguide is located at the input end of the ring waveguide, and the second strip waveguide is located at the output end of the ring waveguide; wherein part of the first strip waveguide passes through the first wedge-shaped groove, and part of the second strip waveguide passes through the second wedge-shaped groove.

2. The photodetector of claim 1, wherein, The first strip waveguide comprises a first waveguide part which passes through the first wedge-shaped groove; The second strip waveguide comprises a second waveguide part which passes through the second wedge-shaped groove.

3. The photodetector of claim 2, wherein, The first strip waveguide further comprises a third waveguide part connected with the first waveguide part; The second strip waveguide further comprises a fourth waveguide part connected with the second waveguide part; The third waveguide part and the fourth waveguide part are arranged in parallel with respect to the ring waveguide.

4. The photodetector of claim 1, wherein, Further comprising: a first protective layer located between the epitaxial layer and the waveguide isolation layer; part of the first strip waveguide is in contact with the first protective layer, and part of the second strip waveguide is in contact with the first protective layer.

5. The photodetector of claim 4, wherein, The thickness of the first protective layer is between 5nm and 10nm.

6. The photodetector of claim 1, wherein, The material forming the first strip waveguide, the second strip waveguide and the ring waveguide comprises silicon oxynitride.

7. The photodetector of claim 1, wherein, Further comprising: a second protective layer covering the side of the waveguide isolation layer where the ring waveguide is formed and exposing the ring waveguide.

8. The photodetector of claim 1, wherein, Further comprising: a light source connected with the input end of the first strip waveguide.

9. A method for fabricating a photodetector, characterized in that, The application relates to a light-emitting device, which comprises: providing an epitaxial layer and forming a first avalanche diode and a second avalanche diode by the epitaxial layer, the first avalanche diode is located in a first through groove formed by the epitaxial layer, and the second avalanche diode is located in a second through groove formed by the epitaxial layer; forming a waveguide isolation layer on one side of the epitaxial layer, the light receiving surfaces of the first avalanche diode and the second avalanche diode are both directed towards the waveguide isolation layer; forming a first wedge-shaped groove penetrating the position where the light receiving surface of the first avalanche diode is located and a second wedge-shaped groove penetrating the position where the light receiving surface of the second avalanche diode is located on the waveguide isolation layer; A first strip waveguide, a second strip waveguide and a ring waveguide are formed on the side of the waveguide isolation layer away from the epitaxial layer, the first strip waveguide is located at the input end of the ring waveguide, and the second strip waveguide is located at the output end of the ring waveguide; part of the first strip waveguide passes through the first wedge-shaped groove, and part of the second strip waveguide passes through the second wedge-shaped groove.

10. The method of claim 9, wherein the method further comprises: Before forming the waveguide isolation layer on the side of the epitaxial layer, further comprising: A first protective layer is formed on the side of the epitaxial layer, and the first protective layer is located between the epitaxial layer and the waveguide isolation layer.

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