High-speed wide-spectral-response photoelectric detector, epitaxial structure and preparation method of high-speed wide-spectral-response photoelectric detector

Abstract

The invention provides a high-speed wide-spectral-response photoelectric detector, an epitaxial structure and a preparation method thereof, and relates to the field of photoelectric chip manufacturing and processing. The epitaxial structure comprises an InP buffer layer, an In < x > Ga < y > As buffer layer, an In < x > 1 Ga < y > 1 As buffer layer, an N-In < x > 2 Ga < y > 2 As contact layer, an In < x > 2 Ga < y > 2 As intrinsic layer, an In < GaAsP > transition layer and a P-In < x > 2 Ga < y > 2 As contact layer which are sequentially grown on a substrate, x + y = 1, x1 + y1 = 1, and x2 + y2 = 1. The response wavelength of the chip containing the epitaxial structure covers 850 nm to 1650 nm, the response speed is high, and the response wavelength is wide.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic chip manufacturing and processing, and more specifically, to a high-speed, wide-spectral-response photodetector, an epitaxial structure, and a method for fabricating the same. Background Technology

[0002] With the advent of the AI ​​era, the fiber optic communication industry has experienced tremendous growth. Fiber optic communication has three main application scenarios: access networks, telecommunications networks, and data centers. Access networks primarily utilize single-mode applications, with speeds evolving from 10GPON to 50G PON. Following the 5G wave in 2020, telecommunications networks are also moving towards 6G, primarily using single-mode applications. Data centers, driven by the AI ​​era, are developing towards 800G and even 1.6T speeds, divided into short-distance and medium-to-long-distance transmission. Short-distance transmission is mainly multi-mode, accounting for over 70%, while medium-to-long-distance transmission is primarily single-mode. The working principle of fiber optic communication is that a transmitter converts electrical signals into optical signals. These optical signals of specific wavelengths are transmitted through optical fibers, and a receiver receives the optical signals and converts them back into electrical signals to complete the signal transmission.

[0003] Optical modules are core components in fiber optic communication systems, performing photoelectric conversion. They mainly consist of a transmitting optical chip (laser) and a probing optical chip (detector). Depending on the application, optical modules are divided into multimode modules (850nm VCSEL chip) for short-distance transmission and single-mode modules (1270-1577nm DFB / EML chip) for medium- to long-distance transmission. Instruments for testing optical modules need to be able to simultaneously test the wavelengths covered by both multimode and single-mode modules; their core operation relies on photoelectric conversion using a photodetector.

[0004] Currently, the most common photodetectors on the market mainly detect GaAs epitaxial structures with wavelengths of 850nm, Si epitaxial structures of 400nm-1100nm, and InGaAs epitaxial structures of 960nm-1650nm. Their narrow spectral response wavelength range and low detection rate cannot meet the testing requirements of high-speed optical modules. Summary of the Invention

[0005] The purpose of this invention is to provide an epitaxial structure for a high-speed, wide-spectral-response photodetector that can cover response wavelengths from 850nm to 1650nm, is compatible with single-mode and multi-mode applications, and can be packaged into a device for use in high-end instruments, such as high-speed oscilloscopes for testing the eye diagram of optical modules.

[0006] Another objective of this invention is to provide a method for fabricating an epitaxial structure of a high-rate, wide-spectral-response photodetector. This method employs MBE (molecular beam epitaxy) to precisely control the content of each component in each alloy layer, thereby reducing lattice defects caused by varying In content during the growth of the epitaxial structure.

[0007] The third objective of this invention is to provide a high-speed, wide-spectral-response photodetector with a chip bandwidth of up to 30 GHz, capable of single-wavelength data transmission at a rate of 100 Gbps.

[0008] The technical problem solved by this invention is achieved by the following technical solution.

[0009] On one hand, embodiments of the present invention provide an epitaxial structure for a high-rate, wide-spectrum-response photodetector, comprising an InP buffer layer and an In... sequentially grown on a substrate. x Ga y As buffer layer, In x1 Ga y1 As buffer layer, N-In x2 Ga y2 As contact layer, In x2 Ga y2 As intrinsic layer, InGaAsP transition layer and P-In x2 Ga y2 As contact layer; x+y=1, x1+y1=1, x2+y2=1.

[0010] Wherein, N-In x2 Ga y2 The As contact layer is N-type doped, P-In x2 Ga y2 The As contact layer is P-type doped. These two layers are used to fabricate the P / N electrodes of the detector, which collect electrons and holes to generate current.

[0011] And In x2 Ga y2 The intrinsic layer (As) is the core layer of the entire detector. This layer is undoped and forms a high-resistivity depletion layer. It receives light and performs photoelectric conversion. Under the action of an external electric field, photogenerated carriers are depleted in the I region, electrons move to the N region, and holes move to the P region, forming a current.

[0012] In some embodiments of the present invention, the value of x is 0.53~0.55, the value of x1 is 0.55~0.6, and the value of x2 is 0.6~0.61.

[0013] In some embodiments of the present invention, the In x2 Ga y2 The response wavelength of the intrinsic As layer is 850nm-1650nm.

[0014] In some embodiments of the present invention, the thickness of the InP buffer layer is 2 μm; In x Ga y The thickness of the As buffer layer is 1µm; In x1 Ga y1 The thickness of the As buffer layer is 1µm; N-In x2 Ga y2 The thickness of the As contact layer is 0.5 μm; In x2 Ga y2 The thickness of the intrinsic As layer is 1 μm; the thickness of the InGaAsP transition layer is 0.5 μm; P-In x2 Ga y2 The thickness of the As contact layer is 0.2 μm.

[0015] In some embodiments of the present invention, the thickness of the substrate is 350 μm.

[0016] In some embodiments of the present invention, the substrate is made of an iron-containing InP alloy.

[0017] On the other hand, embodiments of the present invention provide a method for fabricating an epitaxial structure of a high-rate, wide-spectral-response photodetector, comprising the following steps: S1, Prepare the substrate; S2, based on MBE molecular beam epitaxy, elemental deposition is performed on the substrate according to the elemental ratio of each layer of material to form an epitaxial structure.

[0018] A high-speed, broadband response photodetector, the chip of which contains the aforementioned epitaxial structure.

[0019] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects: The present invention provides an epitaxial structure for a high-speed, wide-spectrum response photodetector that covers the response wavelength range of 850nm-1650nm, with fast response speed and wide response wavelength.

[0020] Based on this epitaxial structure, the photodetector chip has a bandwidth of up to 30 GHz, enabling data transmission at a single-wavelength rate of 100 Gbps. This detector chip can cover a response wavelength range of 850 nm to 1650 nm, is compatible with both single-mode and multi-mode applications, and, after packaging, can be used in high-end instrumentation, such as high-speed oscilloscopes for testing the eye diagrams of optical modules, and as a vector network analyzer used as an optical base to test the transmission characteristics of 850 nm VCSELs or 1270 nm-1577 nm DFB lasers. Attached Figure Description

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 A cross-sectional schematic diagram of a traditional InGaAs / InP epitaxial structure; Figure 2 This is a cross-sectional schematic diagram of the InGaAs / InP epitaxial structure of Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the structure of a chip containing the epitaxial structure of Embodiment 1. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0024] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to specific embodiments.

[0025] Traditional InGaAs / InP epitaxial structures, such as Figure 1 As shown, the main structure is P(p-In) 0.53 Ga 0.47 As)-I (Intrinsic-In) 0.53 Ga 0.47 As)-N(n-In 0.53 Ga 0.47 As) structure. The material of this structure is In. 0.53 Ga 0.47 The As layer is chosen because its lattice is perfectly matched to the InP substrate, resulting in minimal defects during epitaxial growth and allowing for high-quality epitaxial layers. However, the response wavelength of this epitaxial structure (PD) is limited to a minimum of 960 nm. Improving the PD's response rate can be achieved by reducing the PD's optical window to decrease chip capacitance and by reducing the thickness of the I-region to shorten carrier transit time.

[0026] The high-speed, broadband response photodetector provided by this invention employs an InGaAs / InP material system. The composition of the epitaxial structure is modulated to increase the In content and the bandgap of the InGaAs material, thereby achieving a response wavelength coverage of 850nm-1650nm. To obtain a high-quality, high-In-content epitaxial structure, MBE (molecular beam epitaxy) is used to grow the epitaxial structure on a substrate. An InGaAs bandgap gradient buffer layer is added to the substrate to reduce the generation of defects during the epitaxial process.

[0027] For traditional epitaxial structures, InP exhibits strong absorption of short-wavelength light. Therefore, by removing the InP Cap layer, the overall chip thickness is reduced, thereby increasing the responsivity at the short wavelength of 850nm. Finally, the responsivity is further improved by optimizing the antireflection coating of the optical window and adding a high-reflectivity coating on the back of the chip. The high-speed, broadband response photodetector epitaxial structure provided by this invention is as follows: Figure 2 As shown.

[0028] Specifically, embodiments of the present invention provide an epitaxial structure for a high-speed, wide-spectrum-response photodetector. This epitaxial structure includes an InP buffer layer and an In... sequentially grown on a substrate. x Ga y As buffer layer, In x1 Ga y1 As buffer layer, N-In x2 Ga y2 As contact layer, In x2 Ga y2 As intrinsic layer, InGaAsP transition layer and P-In x2 Ga y2 As contact layer; x+y=1, x1+y1=1, x2+y2=1.

[0029] In some embodiments of the present invention, in the above-described epitaxial structure, the value of x is 0.53~0.55, the value of x1 is 0.55~0.6, and the value of x2 is 0.6~0.61, wherein, in the In x2 Ga y2 In the intrinsic layer As, x2=0.6, y2=0.4.

[0030] In some embodiments of the present invention, the In x2 Ga y2 The response wavelength of the intrinsic As layer is 850nm-1650nm.

[0031] In some embodiments of the present invention, the thickness of the InP buffer layer is 2 μm; In x Gay The thickness of the As buffer layer is 1µm; In x1 Ga y1 The thickness of the As buffer layer is 1µm; N-In x2 Ga y2 The thickness of the As contact layer is 0.5 μm; In x2 Ga y2 The thickness of the intrinsic As layer is 1 μm; the thickness of the InGaAsP transition layer is 0.5 μm; P-In x2 Ga y2 The thickness of the As contact layer is 0.2 μm.

[0032] In some embodiments of the present invention, the thickness of the InGaAs intrinsic layer is 1 μm.

[0033] In some embodiments of the present invention, the thickness of the substrate is 350 μm.

[0034] In some embodiments of the present invention, the substrate is made of an iron-containing InP alloy.

[0035] On the other hand, embodiments of the present invention provide a method for fabricating an epitaxial structure of a high-rate, wide-spectral-response photodetector, comprising the following steps: S1, Prepare the substrate; S2, based on MBE molecular beam epitaxy, elemental deposition is performed on the substrate according to the composition ratio of each layer to form an epitaxial structure.

[0036] A high-speed, broadband response photodetector, the chip of which contains the aforementioned epitaxial structure. The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0037] Example 1 The epitaxial structure of this embodiment was prepared according to the following elemental ratios and preparation methods for each layer: InP buffer layer, In x Ga y As buffer layer, In x1 Ga y1 As buffer layer, N-In x2 Ga y2 As contact layer, In x2 Ga y2 As intrinsic layer, InGaAsP transition layer and P-In x2 Ga y2 As is the contact layer; where x=0.54, y=0.46, x1=0.56, y1=0.44, x2=0.6, y2=0.4.

[0038] S1, Prepare the substrate; S2, based on MBE molecular beam epitaxy, elemental deposition is performed on the substrate according to the composition ratio of each layer to form an epitaxial structure.

[0039] Example 2 The epitaxial structure of this embodiment was prepared according to the following elemental ratios and preparation methods for each layer: InP buffer layer, In x Ga y As buffer layer, In x1 Ga y1 As buffer layer, N-In x2 Ga y2 As contact layer, In x2 Ga y2 As intrinsic layer, InGaAsP transition layer and P-In x2 Ga y2 As is the contact layer; where x=0.55, y=0.45, x1=0.58, y1=0.42, x2=0.6, y2=0.4.

[0040] S1, Prepare the substrate; S2, based on MBE molecular beam epitaxy, elemental deposition is performed on the substrate according to the composition ratio of each layer to form an epitaxial structure.

[0041] Example 3 The epitaxial structure of this embodiment was prepared according to the following elemental ratios and preparation methods for each layer: InP buffer layer, In x Ga y As buffer layer, In x1 Ga y1 As buffer layer, N-In x2 Ga y2 As contact layer, In x2 Ga y2 As intrinsic layer, InGaAsP transition layer and P-In x2 Ga y2 As is the contact layer; where x=0.55, y=0.45, x1=0.59, y1=0.41, x2=0.61, y2=0.39.

[0042] S1, Prepare the substrate; S2, based on MBE molecular beam epitaxy, elemental deposition is performed on the substrate according to the composition ratio of each layer to form an epitaxial structure.

[0043] Comparative Example 1 like Figure 1As shown, a conventional epitaxial structure was fabricated. The structure includes: an InP Cap layer with a thickness of 0.5 μm; a P-InGaAs Contact layer with a thickness of 0.2 μm; an InGaAsP Transition layer with a thickness of 0.5 μm; an InGaAs Intrinsic Layer with a thickness of 1 μm; an N-InGaAs Contact Layer with a thickness of 0.5 μm; an InP Buffer Layer with a thickness of 3 μm; and a substrate (InP(Fe)-Sub, containing iron) with a thickness of 350 μm.

[0044] Experimental Example The epitaxial structures of Examples 1-3 and Comparative Example 1 were fabricated into detector chips through processes such as photolithography, cleaning, and thin film deposition. Figure 3 As shown in Table 1, its bandwidth and response wavelength range were tested. Table 1

[0045] The method for testing bandwidth is as follows: a vector network analyzer is used, and the device is tested after it is packaged.

[0046] Response wavelength: Broadband light source test, light is given to the PD optical window, and the magnitude of the current generated by the PD can be used to calculate the responsivity value.

[0047] exist Figure 2 In the middle, P-In x2 Ga y2 As contact layer (P-In) x2 Ga y2 As Contact Layer), with a thickness of 0.2 μm; InGaAsP Transition Layer, with a thickness of 0.5 μm; In x2 Ga y2 As intrinsic layer (In) x2 Ga y2 As an Intrinsic Layer), its thickness is 1 μm; N-In x2 Ga y2 As contact layer (N-In) x2 Ga y2 As a contact layer, its thickness is 0.5 μm; In x1 Ga y1As buffer layer (In) x1 Ga y1 As a buffer layer), its thickness is 1µm; In x Ga y As buffer layer (In) x Ga y As Buffer Layer), with a thickness of 1um; InP Buffer Layer, with a thickness of 2um; Substrate (InP(Fe)-Sub, containing iron), with a thickness of 350um.

[0048] In summary, the embodiments of the present invention provide a high-speed, wide-spectrum response photodetector with a response wavelength covering 850nm-1650nm, characterized by fast response speed and wide response wavelength.

[0049] Based on this epitaxial structure, the photodetector chip has a bandwidth of up to 30 GHz, enabling data transmission at a single-wavelength rate of 100 Gbps. This detector chip can achieve a response wavelength coverage of 850 nm to 1650 nm, is compatible with both single-mode and multi-mode applications, and, when packaged into a device, can be used in high-end instrumentation, such as high-speed oscilloscopes for testing the eye diagrams of optical modules, and as a vector network analyzer used as an optical base to test the transmission characteristics of 850 nm VCSELs or 1270 nm to 1577 nm DFB lasers.

[0050] The embodiments described above are some, but not all, embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. An epitaxial structure for a high-speed, wide-spectral-response photodetector, characterized in that, Including an InP buffer layer and an InP layer grown sequentially on the substrate. x Ga y As buffer layer, In x1 Ga y1 As buffer layer, N-In x2 Ga y2 As contact layer, In x2 Ga y2 As intrinsic layer, InGaAsP transition layer and P-In x2 Ga y2 As contact layer; x+y=1, x1+y1=1, x2+y2=1.

2. The epitaxial structure of the high-speed broadband response photodetector according to claim 1, characterized in that, The value of x is 0.53~0.55, the value of x1 is 0.55~0.6, and the value of x2 is 0.6~0.

61.

3. The epitaxial structure of the high-speed broadband response photodetector according to claim 1, characterized in that, The In x2 Ga y2 The response wavelength of the intrinsic As layer is 850nm-1650nm.

4. The epitaxial structure of the high-speed broadband response photodetector according to claim 1, characterized in that, The thickness of the InP buffer layer is 2µm; In x Ga y The thickness of the As buffer layer is 1µm; In x1 Ga y1 The thickness of the As buffer layer is 1µm; N-In x2 Ga y2 The thickness of the As contact layer is 0.5 μm; In x2 Ga y2 The thickness of the intrinsic As layer is 1 μm; the thickness of the InGaAsP transition layer is 0.5 μm; P-In x2 Ga y2 The thickness of the As contact layer is 0.2 μm.

5. The epitaxial structure of the high-speed broadband response photodetector according to claim 1, characterized in that, The thickness of the substrate is 350 μm.

6. The epitaxial structure of the high-speed broadband response photodetector according to claim 1, characterized in that, The substrate is made of an iron-containing InP alloy.

7. A method for fabricating an epitaxial structure of a high-rate broadband spectral response photodetector as described in any one of claims 1-6, characterized in that, Includes the following steps: S1, Prepare the substrate; S2, based on MBE molecular beam epitaxy, elemental deposition is performed on the substrate according to the composition ratio of each layer to form an epitaxial structure.

8. A high-speed, wide-spectral-response photodetector, characterized in that, Includes the epitaxial structure as described in any one of claims 1-6.

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