High-speed silicon-based germanium photoelectric detector

Abstract

The invention discloses a high-speed silicon-based germanium photoelectric detector, and belongs to the technical field of silicon-based optoelectronic integration. The invention aims to alleviate the inherent contradiction of high performance and deployment cost in the existing silicon-based photoelectric detector. The device comprises an SOI substrate layer; the grating structure and the heat insulation photonic waveguide are formed after the top silicon substrate is etched; the N-type doped region and the P-type doped region are formed after the top silicon substrate is doped; the germanium absorption region is formed on the top layer silicon in an epitaxial manner; the first electrode grows on the N-type doped region; and the second electrode grows on the P-type doped region, and the distance between the first electrode and the middle absorption region and the distance between the second electrode and the middle absorption region are asymmetrical to form an accelerated asymmetrical electrode. Seen from the cross section, the N-type doped region and the P-type doped region are located on the two sides respectively, the germanium absorption region is located between the N-type doped region and the P-type doped region, and a transverse PIN junction structure is formed. The N-type doped region sequentially comprises an N lightly doped region, an N middle doped region and an N heavily doped region from the central region to the end face, and the first electrode is located in the N heavily doped region. The P-type doped region sequentially comprises a P lightly doped region, a P middle doped region and a P heavily doped region from the central region to the end face, and the second electrode is located in the P heavily doped region.

Description

Technical Field

[0001] The present invention relates to a high-speed silicon-based germanium photoelectric detector, and in particular to the field of silicon-based optoelectronic integration. Background Art

[0002] In today's information age, the booming development of applications such as big data, cloud computing, and artificial intelligence has spurred a surge in demand for data communication capabilities. This technological leap places unprecedented demands on the performance of core photodetectors to enable large-scale data exchange in next-generation data centers. Simultaneously, these demanding requirements impose stringent requirements on cost-effectiveness, compact form factors, and scalable integration potential. Currently, III-V composite photodetectors dominate high-speed applications due to their excellent optoelectronic properties (high carrier mobility, direct bandgap transitions, and wide spectral response). However, their lattice mismatch with silicon presents a key limitation for hybrid integration. Among various optical interconnect solutions, germanium-silicon photodetectors have become a key technology to replace traditional indium phosphide devices due to their mass production compatibility with silicon-based processes, submicron integration accuracy, and cost advantages. However, inherent material limitations hinder the high-speed operation of Ge / Si photodetectors, while the existing structures' reliance on complex architectures and multi-step manufacturing processes hinders the full realization of their cost-effectiveness, compact form factors, and scalable integration potential. Summary of the Invention

[0003] In order to alleviate the inherent contradiction between performance and high deployment cost in existing silicon-based photodetectors, the present invention proposes a high-speed photodetector based on a standard silicon photonic platform, which has the advantages of high performance, high integration and low cost.

[0004] The present disclosure provides a silicon-germanium detector, comprising: an SOI substrate layer 1, a grating coupler 2, a waveguide structure 3 formed by etching a top silicon layer, an N-doped region 4 formed by doping the top silicon layer, a P-doped region 5 formed by doping the top silicon layer, a germanium absorption region 6 formed by epitaxial germanium on the top silicon layer, a first electrode 7 doped in the N-doped region, a second electrode 8 doped in the P-doped region, and a tungsten through-hole 9 for connecting the electrodes to the doped regions; the N-doped region 4 and the P-doped region 5 are respectively located on both sides, and the germanium absorption region 6 is located between the P-doped region 4 and the N-doped region 5, forming a lateral PIN junction structure.

[0005] According to an embodiment of the present disclosure, light enters the silicon waveguide through a grating coupler, and then passes through a silicon ridge waveguide, a curved waveguide, and a gradient waveguide. The gradient waveguide is located on one side of the germanium absorption region and its width gradually decreases along the direction of forward light propagation.

[0006] According to the embodiment of the present disclosure, the N-doped region 4 includes three layers of doped regions, which are the N lightly doped region 4-1, the N medium doped region 4-2, and the N heavily doped region 4-3 from the center close to the germanium region to the farthest from the germanium region, and the doping concentration increases accordingly. The concentration of the N heavily doped region is not less than 1.0×10 19 cm -3 The setting of three-layer doped regions is used to form a high electric field and reduce carrier recombination.

[0007] According to the embodiment of the present disclosure, the P-doped region 5 includes three layers of doped regions, which are the P lightly doped region 5-1, the P medium doped region 5-2, and the P heavily doped region 5-3 from the center close to the germanium region to the farthest from the germanium region. The doping concentration increases in this order, and the concentration of the P heavily doped region is not less than 1.0×10 19 cm -3 The setting of three-layer doped regions is used to form a high electric field and reduce carrier recombination.

[0008] According to an embodiment of the present disclosure, the first electrode is located in the N-doped region 7 , and the electrode and the doped region are connected via a tungsten pass.

[0009] According to an embodiment of the present disclosure, the second electrode is located in the P-doped region 8 , and the electrode and the doped region are connected via a tungsten pass.

[0010] The beneficial effects of the present invention are:

[0011] 1. The waveguide structures used in the present invention include silicon ridge waveguides, curved waveguides, and gradient waveguides to achieve adiabatic transmission of photons, thereby achieving uniform distribution of the light field in the germanium region, reducing space charge effects, and improving the detector bandwidth and responsivity performance.

[0012] 2. The present invention adopts a multi-doping region setting, and both the P-doping region and the N-doping region adopt a three-level doping setting. This design realizes a high electric field setting, uniformizes the carrier distribution, effectively reduces the chip capacitance, effectively reduces the detector dark current and improves the device bandwidth.

[0013] 2. The asymmetric electrode arrangement of the present invention, that is, the distance from the first electrode to the germanium region is greater than the distance from the second electrode to the germanium region, forms a directional acceleration field, realizes carrier acceleration, ensures the matching of the transmission time of holes and electrons, and effectively improves the detector bandwidth. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a cross-sectional view of a high-speed silicon-based photodetector of the present invention;

[0015] Figure 2 is a top view of the high-speed silicon-based photodetector of the present invention;

[0016] In the figure, reference numeral 1 is the SOI substrate layer, 2 is the grating coupler, 3 is the waveguide structure, 4 is the N-doped region, 5 is the P-doped region, 6 is the germanium absorption region, 7 is the first electrode, 8 is the second electrode, and 9 is the tungsten through hole. DETAILED DESCRIPTION

[0017] Specific embodiment 1: The silicon germanium detector includes: an SOI substrate layer 1, a grating coupler 2 formed by etching the top silicon layer, a waveguide structure 3 formed by etching the top silicon layer, an N-doped region 4 formed by doping the top silicon layer, a P-doped region 5 formed by doping the top silicon layer, a germanium absorption region 6 formed by epitaxial germanium on the top silicon layer, a first electrode 7 doped in the N-doped region, a second electrode 8 doped in the P-doped region, and a tungsten through-hole 9 for connecting the electrodes and the doped regions; the N-doped region 4 and the P-doped region 5 are respectively located on both sides, and the germanium absorption region 6 is located between the N-doped region 4 and the P-doped region 5, forming a lateral PIN junction structure.

[0018] Specific implementation method 2: Figure 1 As shown, based on the specific embodiment one, the SOI substrate layer 1 is composed of three layers, namely, the bottom silicon substrate layer 1-1, the SiO2 substrate layer 1-2, and the top silicon substrate layer 1-3 from bottom to top; the top silicon substrate layer 1-3 is used to etch to form the grating coupler 2, the waveguide structure 3, and is doped to form the N-doped region 4 and the P-doped region 5.

[0019] Specific implementation method three: Figure 1 As shown, based on the first embodiment, the grating coupler 2 formed by etching the top silicon layer includes periodic etched regions and periodic non-etched regions. The grating coupler is a key component for coupling the optical field between the optical fiber and the silicon waveguide. It couples light from the optical fiber into the silicon waveguide 3 through the diffraction effect of the grating structure composed of periodic etched and non-etched regions.

[0020] Specific implementation method four: Figure 1 As shown, based on the first embodiment, the waveguide structure 3 formed by etching the top silicon layer includes a silicon ridge waveguide, a curved waveguide, and a gradient waveguide. The waveguide structure 3 is used for adiabatic coupling of photons. The gradient waveguide is located on one side of the germanium absorption region, and its width gradually decreases along the direction of light propagation to achieve evanescent wave coupling from the waveguide structure 3 to the germanium absorption region 6, thereby enhancing absorption in the germanium absorption region 6 and achieving a uniform light field distribution.

[0021] Specific implementation method five: Figure 1 As shown, based on the specific embodiment 1, the N-doped region 4 formed by doping the top silicon layer includes three layers of doped regions, namely, the N lightly doped region 4-1, the N medium doped region 4-2, and the N heavily doped region 4-3 from the center close to the germanium region to the farthest from the germanium region, and the doping concentration increases accordingly. The doping concentration of the N heavily doped region is not less than 1.0×10 19 cm-3 .

[0022] Specific implementation method six: Figure 1 As shown, based on the specific embodiment 1, the P-doped region 5 formed by doping the top silicon layer includes three layers of doped regions, namely, the P lightly doped region 5-1, the P medium doped region 5-2, and the P heavily doped region 5-3 from the center close to the germanium region to the farthest from the germanium region, and the doping concentration increases accordingly. The doping concentration of the P heavily doped region is not less than 1.0×10 19 cm -3 .

[0023] Specific implementation method seven: Figure 1 As shown, based on the first embodiment, the germanium absorption region 6 formed by epitaxial germanium on the top silicon layer is located between the N-doped region 4 and the P-doped region 5, forming a lateral PIN junction structure.

[0024] Specific implementation eight: Figure 1 As shown, based on the first embodiment, the first electrode 7 is located on the N heavily doped region 4 - 3 and is connected to the P heavily doped region 4 - 3 through a tungsten through hole.

[0025] Specific implementation method nine: Figure 1 As shown, based on the first embodiment, the second electrode 8 is located on the P heavily doped region 5 - 3 and is connected to the P heavily doped region 5 - 3 through a tungsten through hole.

[0026] Specific implementation method ten: Figure 1 As shown, based on the first embodiment, the ratio of the distance from the first electrode 7 to the center of the absorption region and the distance from the center of the absorption region to the second electrode 8 is 1.5:1.

[0027] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the present profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical content disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement of the above embodiments made according to the technical essence of the present invention, within the spirit and principles of the present invention, without departing from the content of the technical solution of the present invention, shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A high-speed silicon-germanium photodetector, characterized in that: The invention comprises an SOI substrate layer, a grating coupler and a waveguide structure formed by etching a top silicon substrate, an N-doped region formed by doping a top silicon layer, a P-doped region formed by doping a top silicon layer, a germanium absorption region formed by epitaxial germanium on the top silicon layer, a first electrode doped in the N-doped region, and a second electrode doped in the P-doped region; the P-doped region and the N-doped region are respectively located on both sides, and the germanium absorption region is located between the P-doped region and the N-doped region, forming a lateral PIN junction structure.

2. The high-speed silicon-germanium photodetector according to claim 1, characterized in that: The SOI substrate layer consists of three layers, which are, from bottom to top, a bottom silicon substrate layer 1-1, a SiO2 substrate layer 1-2, and a top silicon substrate layer 1-3.

3. The high-speed silicon-germanium photodetector according to claim 1, characterized in that: The silicon waveguide includes a silicon ridge waveguide, a curved waveguide and a gradient waveguide. The width of the gradient waveguide increases gradually and is located on one side of the absorption region.

4. The high-speed silicon-germanium photodetector according to claim 1, characterized in that: The P-doped region includes three layers of doped regions, which are a P lightly doped region, a P medium doped region, and a P heavily doped region from the center close to the germanium region to the center farthest from the germanium region.

5. The high-speed silicon-germanium photodetector according to claim 1, characterized in that: The N-doped region includes three layers of doped regions, which are an N lightly doped region, an N medium doped region, and an N heavily doped region from the center close to the germanium region to the center farthest from the germanium region.

6. The high-speed silicon-germanium photodetector according to claim 1, characterized in that: The first electrode is located on the N heavily doped region.

7. The high-speed silicon-germanium photodetector according to claim 1, characterized in that: The second electrode is located on the P heavily doped region.

8. The high-speed silicon-germanium photodetector according to claim 1, characterized in that: The first electrode and the second electrode have different distances from the middle absorption region, forming asymmetric electrodes.

9. The high-speed silicon-germanium photodetector according to claim 1, characterized in that: The first and second electrodes are connected to the doped region through tungsten vias.

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