阅读说明：本技术 波导耦合的雪崩光电探测器及其制备方法 (Waveguide-coupled avalanche photodetector and preparation method thereof ) 是由 庞雅青 刘智 成步文 郑军 薛春来 于 2021-08-31 设计创作，主要内容包括：本发明提供了一种波导耦合的雪崩光电探测器及其制备方法,其中,本发明的一个方面提供了一种波导耦合的雪崩光电探测器,包括：SOI衬底,包括：底部硅材料层、中间二氧化硅填埋层和顶层硅；倍增层,覆盖于顶层硅上,倍增层上形成有电荷层；光吸收层,覆盖于电荷层上,光吸收层包括量子点层和量子点层上部的盖层形成的周期结构,光吸收层上形成有掺杂区；绝缘介质层,覆盖于部分所述中间二氧化硅填埋层、部分顶层硅和掺杂区上,在绝缘介质层上开有电极窗口；电极,电极包括n电极和p电极,设置于电极窗口中。(The invention provides a waveguide-coupled avalanche photodetector and a preparation method thereof, wherein one aspect of the invention provides a waveguide-coupled avalanche photodetector, which comprises the following steps: an SOI substrate comprising: a bottom silicon material layer, an intermediate silicon dioxide filling layer and top silicon; the multiplication layer covers the top layer silicon, and a charge layer is formed on the multiplication layer; the light absorption layer covers the charge layer, the light absorption layer comprises a quantum dot layer and a periodic structure formed by a cover layer on the quantum dot layer, and a doped region is formed on the light absorption layer; the insulating medium layer covers part of the middle silicon dioxide filling layer, part of the top silicon and the doped region, and an electrode window is formed in the insulating medium layer; and the electrodes comprise an n electrode and a p electrode and are arranged in the electrode windows.)

1. A waveguide-coupled avalanche photodetector, comprising:

an SOI substrate comprising: a bottom silicon material layer, an intermediate silicon dioxide filling layer and top silicon;

the multiplication layer covers the top layer silicon, and a charge layer is formed on the multiplication layer;

the light absorption layer covers the charge layer, the light absorption layer comprises a quantum dot layer and a periodic structure formed by a cover layer on the quantum dot layer, and a doped region is formed on the light absorption layer;

the insulating medium layer covers part of the middle silicon dioxide buried layer, part of the top silicon and the doped region, and an electrode window is formed in the insulating medium layer;

an electrode including an n-electrode and a p-electrode disposed in the electrode window.

2. The detector according to claim 1, wherein the periodic structure has a period number of 10-30; the light absorbing layer is free of a p-n junction structure.

3. The detector of claim 1, wherein the charge layer and the doped region are both p-type doped, and the charge layer has a doping concentration of 1 x 10 each¹⁷/cm³～3×10¹⁷/cm³The doping depth is 50-200 nm; the doping concentration of the doping region is more than 5 x 10¹⁸/cm³And the doping depth is less than 150 nm.

4. The detector of claim 3, wherein the doping pattern of the p-type doping comprises at least one of: ion implantation, diffusion, or in-situ doping.

5. The detector of claim 1, wherein the top layer silicon is doped N-type with a doping concentration greater than 5 x 10¹⁸/cm³(ii) a The thickness of the multiplication layer is 700-800 nm.

6. The detector of claim 1, wherein the material of the insulating dielectric layer comprises: silicon dioxide or silicon nitride, and the thickness of the insulating medium layer is 800-1300 nm.

7. The detector of claim 1, wherein the p-electrode is disposed in the electrode window opened on the insulating dielectric layer overlying the doped region; the n-electrode comprises a first n-electrode and a second n-electrode, and the first n-electrode and the second n-electrode are respectively arranged in the electrode windows formed on the insulating medium layer covering part of the top silicon.

8. A method of making a detector according to any one of claims 1-7, comprising:

preparing a multiplication layer on the top silicon of the SOI substrate;

forming a charge layer on the multiplication layer;

epitaxially growing a light absorption layer on the charge layer, wherein the light absorption layer comprises a quantum dot layer and a periodic structure formed by a cover layer on the quantum dot layer;

forming a doped region on the light absorption layer;

etching part of the multiplication layer, part of the charge layer, part of the light absorption layer and part of the doped region to expose part of the top silicon;

etching part of the top layer silicon until part of the middle silicon dioxide filling layer of the SOI substrate is exposed to obtain the etched part of the top layer silicon;

preparing an insulating medium layer on the middle silicon dioxide filling layer of part of the SOI substrate, the etched part of the top silicon and the doped region;

an electrode window is formed on the insulating medium layer;

and respectively manufacturing an n electrode and a p electrode in the electrode window.

9. The method of claim 8, wherein the light absorption layer is grown in sequence with 10 to 30 cycles by the quantum dot layer and the cap layer on the quantum dot layer.

10. The method of claim 8, wherein the n-electrode comprises a first n-electrode and a second n-electrode, and fabricating an n-electrode and a p-electrode in the electrode window, respectively, comprises:

manufacturing the p electrode in the electrode window formed on the insulating medium layer covering the doped region;

and respectively manufacturing the first n electrode and the second n electrode in the electrode windows formed on the insulating medium layer covering part of the top layer silicon.

Technical Field

The invention relates to the field of photoelectric detectors, in particular to a waveguide-coupled avalanche photoelectric detector and a preparation method thereof.

Background

The single photon detection has wide application prospects in various fields such as quantum communication, optical time domain reflectometers, Quantum Key Distribution (QKD), laser ranging, three-dimensional imaging, time-resolved spectroscopy, circuit testing, biological imaging and the like, and becomes a research hotspot in the field of recent photoelectronics. At present, InGaAs/InP is used as a single photon detector mainly used in the communication field, when in use, because the post pulse caused by the capture and re-release of carriers in the avalanche process is large, a long dead time is needed to release the captured carriers, and the long dead time is caused.

The pure silicon single photon avalanche photodetector has better recovery time, but in the pure silicon single photon avalanche photodetector, because the forbidden bandwidth of silicon is 1.12eV, optical signals with the wavelength larger than 1100nm cannot be effectively absorbed, and the penetration of short wavelength optical signals (< 400nm) in silicon is limited, the silicon detector can only effectively detect optical signals with the wavelength of 300 nm-1100 nm usually, and the application of the silicon detector in communication bands is limited. The germanium material has higher light absorption efficiency in the near infrared band and is completely compatible with the CMOS (complementary Metal Oxide semiconductor) process of silicon. Epitaxial germanium materials on silicon are a large mismatch system that can lead to the problem of high dark counts for avalanche photodetectors.

Disclosure of Invention

In view of the above problems, the present invention provides a waveguide-coupled avalanche photodetector and a method for manufacturing the same, which solve the problems of high dark count of devices, etc., and improve the light absorption efficiency by using a waveguide coupling method, thereby effectively compensating the problem of low quantum dot absorption coefficient.

To achieve the above object, an aspect of the present invention provides a waveguide-coupled avalanche photodetector, comprising: an SOI substrate comprising: a bottom silicon material layer, an intermediate silicon dioxide filling layer and top silicon; the multiplication layer covers the top layer silicon, and a charge layer is formed on the multiplication layer; the light absorption layer covers the charge layer, the light absorption layer comprises a quantum dot layer and a periodic structure formed by a cover layer on the quantum dot layer, and a doped region is formed on the light absorption layer; the insulating medium layer covers part of the middle silicon dioxide filling layer, part of the top silicon and the doped region, and an electrode window is formed in the insulating medium layer; and the electrodes comprise an n electrode and a p electrode and are arranged in the electrode windows.

According to the embodiment of the invention, the number of the periods of the periodic structure is 10-30; the light absorbing layer has no p-n junction structure.

According to the embodiment of the invention, the charge layer and the doped region are both doped p-type, and the doping concentration of the charge layer is 1 multiplied by 10¹⁷/cm³～3×10¹⁷/cm³The doping depth is 50-200 nm; the doping concentration of the doped region is more than 5 multiplied by 10¹⁸/cm³And the doping depth is less than 150 nm.

According to an embodiment of the present invention, wherein the doping manner of the p-type doping includes at least one of: ion implantation, diffusion, or in-situ doping.

According to the embodiment of the invention, the top layer silicon is doped in an N type, and the doping concentration is more than 5 x 10¹⁸/cm³(ii) a The thickness of the multiplication layer is 700-800 nm.

According to the embodiment of the invention, the material of the insulating medium layer comprises: silicon dioxide or silicon nitride, and the thickness of the insulating medium layer is 800-1300 nm.

According to the embodiment of the invention, the p electrode is arranged in an electrode window formed on an insulating medium layer covering the doped region; the n electrode comprises a first n electrode and a second n electrode, and the first n electrode and the second n electrode are respectively arranged in an electrode window formed on an insulating medium layer covering part of the top layer silicon.

Another aspect of the present invention provides a method for preparing a waveguide-coupled avalanche photodetector, including: preparing a multiplication layer on the top silicon of the SOI substrate; forming a charge layer on the multiplication layer; epitaxially growing a light absorption layer on the charge layer, wherein the light absorption layer comprises a quantum dot layer and a periodic structure formed by a cover layer on the quantum dot layer; forming a doped region on the light absorption layer; etching part of the multiplication layer, part of the charge layer, part of the light absorption layer and part of the doped region to expose part of the top silicon; etching part of the top layer silicon until the silicon dioxide filling layer of the SOI substrate is exposed to obtain the etched part of the top layer silicon; preparing an insulating medium layer on the middle silicon dioxide filling layer of part of the SOI substrate, the etched part of the top silicon and the doped region; an electrode window is formed on the insulating medium layer; and respectively manufacturing an n electrode and a p electrode in the electrode window.

According to the embodiment of the invention, the light absorption layer forms a cycle by growing the quantum dot layer and the cap layer on the quantum dot layer in sequence, and the cycle number is 10-30.

According to an embodiment of the present invention, wherein the n-electrode includes a first n-electrode and a second n-electrode, and the n-electrode and the p-electrode are respectively fabricated in the electrode window, including: manufacturing a p electrode in an electrode window formed on the insulating medium layer covering the doped region; and respectively manufacturing a first n electrode and a second n electrode in electrode windows formed on the insulating medium layer covering part of the top layer silicon.

Based on the technical scheme, compared with the prior art, the invention has the following beneficial effects:

(1) the invention provides a waveguide-coupled avalanche photodetector, which adopts a periodic structure formed by covering a quantum dot layer and a cover layer on the upper part of the quantum dot layer as a light absorption layer, reduces dislocation generated in germanium-silicon heteroepitaxy, and reduces dark count of a device.

(2) By adopting a waveguide coupling mode, incident light is transversely absorbed in the device, the light absorption is enhanced by adjusting the length of the waveguide, the detection efficiency of the device is improved, and the detection and avalanche amplification of optical signals are realized.

Drawings

Figure 1 schematically illustrates a schematic structural view of a waveguide-coupled avalanche photodetector according to an embodiment of the present invention;

figure 2 schematically illustrates a flow chart of a method of fabricating a waveguide-coupled avalanche photodetector according to an embodiment of the present invention;

fig. 3 schematically shows a schematic structural diagram of a method of fabricating a waveguide-coupled avalanche photodetector according to an embodiment of the present invention.

[ description of reference ]:

100: SOI substrate

110: bottom silicon material layer

120: intermediate silicon dioxide filling layer

130: top layer silicon

200: multiplication layer

210: charge layer

300: light absorbing layer

310: quantum dot layer

320: capping layer on top of quantum dot layer

400: doped region

500: insulating medium layer

610: p electrode

620: first n electrode

630: second n electrode

Detailed Description

In order that the objects, technical solutions and advantages of the present invention will become more apparent, the present invention will be further described in detail with reference to the accompanying drawings in conjunction with the following specific embodiments.

In the related art, single photon detection has the problems of high mismatch, high dark count, low efficiency and the like in application. According to the invention, the self-covering multi-layer quantum dot material is epitaxially coated on the silicon substrate to serve as the absorption layer, so that dislocation among materials can be reduced, dark count of a device is reduced, light enters transversely in a waveguide coupling mode, and light absorption is enhanced in a transverse absorption mode, so that the efficiency of the avalanche photodetector is improved, and detection and avalanche amplification of optical signals are realized.

Figure 1 schematically shows a schematic diagram of a waveguide-coupled avalanche photodetector according to an embodiment of the present invention.

As shown in fig. 1, a waveguide-coupled avalanche photodetector includes: an SOI substrate 100, a multiplication layer 200, a light absorption layer 300, an insulating dielectric layer 500, and an electrode.

The components of the waveguide-coupled avalanche photodetector are described in detail below.

An SOI substrate 100, comprising: a bottom silicon material layer 110, an intermediate silicon dioxide buried layer 120, and a top silicon layer 130.

And a multiplication layer 200 covering the top silicon layer 130, wherein a charge layer 210 is formed on the multiplication layer 200.

A light absorbing layer 300 overlying the charge layer 210, the light absorbing layer 300 comprising: the quantum dot layer 310 and the cap layer 320 on the quantum dot layer form a periodic structure, and the doped region 400 is formed on the light absorption layer 300.

And the insulating dielectric layer 500 covers part of the intermediate silicon dioxide buried layer 120, part of the top layer silicon 130 and the doped region 400, and an electrode window is formed on the insulating dielectric layer 500.

Electrodes, including a p-electrode 610 and an n-electrode, the n-electrode may include: a first n-electrode 620 and a second n-electrode 630.

According to the embodiment of the invention, the self-covering multilayer quantum dot material is adopted as the light absorption layer, so that dislocation generated in germanium-silicon heteroepitaxy is reduced, dark count of the device is reduced, meanwhile, a waveguide coupling mode is adopted, so that incident light is transversely absorbed in the avalanche photodetector, the absorption of light is enhanced by adjusting the length of the waveguide, the detection efficiency of the device is improved, and the detection and avalanche amplification of optical signals are realized.

According to the embodiment of the invention, the multiplication layer 200, the charge layer 210, the light absorption layer 300 and the doped region 400 are etched, the SOI top layer silicon 130 is etched, the ridge waveguide is formed, the incident light is transversely absorbed in the waveguide, and the light absorption efficiency can be improved by increasing the length of the waveguide.

According to an embodiment of the present invention, the top silicon 130 is a heavily doped N-type material with a doping concentration greater than 5 × 10¹⁸/cm³To achieve good ohmic contact; the thickness of the intermediate buried silicon dioxide layer 120 should be greater than 1 μm.

According to the embodiment of the invention, the multiplication layer 200 can be lightly doped silicon or intrinsic silicon material, the resistivity is greater than 1 Ω/cm, and the thickness of the multiplication layer 200 can be 700-800 nm.

According to an embodiment of the present invention, the charge layer 210 is p-type doped, and the doping concentration of the charge layer may be1×10¹⁷/cm³～3×10¹⁷/cm³The doping depth is 50 to 200nm, preferably 100 nm.

According to an embodiment of the present invention, the doping manner may include, but is not limited to: ion implantation or diffusion; the dopant ions may include, but are not limited to: boron or gallium ions.

According to an embodiment of the present invention, the charge layer 210 is used to adjust the electric field distribution and intensity of the multiplication layer 200 to achieve silicon avalanche multiplication signal amplification.

According to the embodiment of the present invention, the number of cycles of the periodic structure composed of the quantum dot layer 310 and the cap layer 320 on the quantum dot layer may be 10 to 30, and may be preferably 20; the light absorbing layer 300 has no p-n junction structure.

According to an embodiment of the present invention, the periodic structure may be formed alternately for each period of the quantum dot layer and the cap layer on the upper portion of the quantum dot layer. According to the embodiment of the present invention, for example, the number of the periodic structures may be preferably 20, and in the periodic structure, from bottom to top, the thickness of the cap layer 320 on the quantum dot layer in the 1 st to 19 th periodic structures may be 15 to 20nm, the thickness of the cap layer 320 on the quantum dot layer in the last period in the periodic structure and the 20 th period may be 300 to 500nm, and the thickness of the quantum dot layer in each periodic structure may be 2 to 3 nm.

It should be noted that the periodic structure composed of quantum dot layer 310 and cap layer 320 on top of the quantum dot layer in fig. 1 is only illustrative, and does not limit the period number of the periodic structure of the present invention.

According to an embodiment of the present invention, by extending a cap layer with a certain thickness, i.e., the cap layer 320 on the upper portion of the quantum dot layer, over the quantum dot layer 310, the optical field center distribution position is adjusted by adjusting the thickness of the uppermost cap layer, so that the optical field center is distributed in the center of the quantum dot material of the light absorption layer 300.

According to the embodiment of the invention, each quantum dot layer 310 is very thin and has the thickness of 2-3 nm, and the growth is stopped when dislocation is not generated, so that the dislocation density is reduced compared with the conventional thin film material, and the dark count of the device is reduced.

According toIn the embodiment of the invention, the doped region is doped p-type, and the doping concentration of the doped region is more than 5 multiplied by 10¹⁸/cm³And the doping depth is less than 150 nm.

According to an embodiment of the present invention, the doping manner may include, but is not limited to: ion implantation, diffusion or in-situ doping; the dopant ions may include, but are not limited to: boron or gallium ions.

According to the embodiment of the invention, when an electric field is applied to the device, the electric field firstly enters the charge layer 210, the carriers in the charge layer 210 are firstly depleted, the electric field enters the light absorption layer 300 after depletion, electrons generated by the light absorption layer drift towards the multiplication layer 200 and holes drift towards the doping layer 400 under the action of the drift electric field of the light absorption layer, so that the purpose of extracting the photon-generated carriers is achieved, and avalanche multiplication is realized.

According to an embodiment of the present invention, the material of the insulating dielectric layer 500 may include, but is not limited to: silicon dioxide or silicon nitride, and the thickness of the insulating medium layer is 800-1300 nm.

According to the embodiment of the invention, the insulating medium layer can be used for protecting the electrical isolation of the material covered in the avalanche photodetector from the external environment, and avoiding the pollution of foreign objects or the damage of external force and the like.

According to the embodiment of the present invention, the p-electrode 610 is disposed in a silicon dioxide electrode window formed on the insulating dielectric layer 500 covering the doped region 400, and electrically connected to the doped region 400 to form a good ohmic contact.

According to the embodiment of the present invention, the p-electrode 610 is disposed at the edge of the doped region 400, not at the center of the doped region, to reduce the absorption of light by the metal.

According to the embodiment of the invention, the first n-electrode 620 and the second n-electrode 630 are respectively disposed in silicon dioxide electrode windows opened on the insulating medium layer 500 covering part of the top layer silicon 130, and are respectively electrically connected with the top layer silicon 130 to form a good ohmic contact.

Figure 2 schematically illustrates a flow chart of a method of fabricating a waveguide-coupled avalanche photodetector according to an embodiment of the present invention; fig. 3 schematically shows a schematic structural diagram of a method of fabricating a waveguide-coupled avalanche photodetector according to an embodiment of the present invention.

As shown in fig. 2, the method includes steps S201 to S207.

In step S201, a multiplication layer 200 is prepared on the top silicon 130 of the SOI substrate 100.

According to an embodiment of the present invention, an SOI substrate has a three-layer structure including: a bottom silicon material layer 110, an intermediate silicon dioxide buried layer 120, and a top silicon layer 130. The multiplication layer 200 is epitaxially fabricated on the top silicon 130 of the SOI substrate 100. As shown in fig. 3 (a).

According to the embodiment of the invention, the thickness of the top silicon 130 of the SOI substrate 100 can be 220nm, the crystal orientation can be (100) direction, the top silicon 130 is heavily n-doped, and the doping concentration is more than 5 x 10¹⁸/cm³。

According to the embodiment of the invention, the thickness of the multiplication layer 200 can be 700-800 nm, and the thickness can be changed along with the adjustment of the multiplication factor.

In step S202, a charge layer 210 is formed on the multiplication layer 200.

According to the embodiment of the invention, the charge layer 210 is prepared on the multiplication layer 200 by means of ion implantation or diffusion, and the charge layer 210 is doped in a P type.

According to an embodiment of the present invention, the charge layer 210 is formed on the multiplication layer 200 by ion implantation or diffusion using the photoresist as a mask, as shown in fig. 3 (b).

According to an embodiment of the present invention, the charge layer 210 is doped P-type with a doping concentration of 1 × 10¹⁷/cm³～3×10¹⁷/cm³The doping depth may be 50 to 200nm, and preferably 100 nm.

Step S203 is to epitaxially grow the light absorbing layer 300 on the charge layer 210 and form the doped region 400 on the light absorbing layer 300, wherein the light absorbing layer 300 includes a periodic structure formed by the quantum dot layer 310 and the cap layer 320 on the quantum dot layer 310.

According to an embodiment of the present invention, forming the light absorbing layer 300 on the charge layer 210 may include: cleaning the unfinished device, putting the cleaned unfinished device into an ultra-high vacuum chemical vapor deposition system (UHV-CVD) for epitaxy, growing a quantum dot layer 310 and a cover layer 320 on the upper part of the quantum dot layer in sequence, and forming a light absorption layer 300 after growing for a plurality of cycles; forming the doped region 400 on the light absorbing layer 300 may include: the doped region 400 is formed by annealing after ion doping. As shown in fig. 3 (c).

According to an embodiment of the invention, the material of the quantum dot layer 310 may include one of: germanium quantum dots, germanium tin quantum dots.

According to the embodiment of the present invention, the number of cycles of the periodic structure formed by the quantum dot layer 310 and the quantum dot layer upper cap layer 320 may be 10 to 30, and may preferably be 20 cycles, and the thickness of the cap layer 320 on the quantum dot layer in the last cycle of the periodic structure may be 400 to 500 nm.

According to an embodiment of the present invention, the periodic structure may be formed alternately for each period of the quantum dot layer and the cap layer on the upper portion of the quantum dot layer.

According to the embodiment of the present invention, for example, the number of the periodic structures may be preferably 20, and in the periodic structure, from bottom to top, the thickness of the cap layer 320 on the quantum dot layer in the 1 st to 19 th periodic structures may be 15 to 20nm, the thickness of the cap layer 320 on the quantum dot layer in the last period in the periodic structure and the 20 th period may be 300 to 500nm, and the thickness of the quantum dot layer in each periodic structure may be 2 to 3 nm.

It should be noted that the periodic structure composed of quantum dot layer 310 and cap layer 320 on the quantum dot layer in fig. 3(c) is only illustrative and does not limit the period number of the periodic structure of the present invention.

According to the embodiment of the present invention, by extending a cap layer with a certain thickness, i.e., the cap layer 320 on the upper portion of the quantum dot layer, on the multi-layered self-capping quantum dot layer 310, the distribution position of the optical field center is adjusted by adjusting the thickness of the uppermost cap layer, so that the optical field center is distributed at the center of the self-capping quantum dot material of the optical absorption layer 300.

According to the embodiment of the present invention, the doped region 400 is a P-type heavily doped region, and the doping manner may include, but is not limited to: ion implantation, diffusion, or in situ doping, the dopant ions may include, but are not limited to: boron or gallium ions.

In step S204, a portion of the multiplication layer 200, a portion of the charge layer 210, a portion of the light absorption layer 300, and a portion of the doped region 400 are etched to expose a portion of the top silicon 130.

In step S205, a portion of the top silicon 130 is etched until the intermediate silicon dioxide buried layer 120 of the SOI substrate is exposed, so as to obtain an etched portion of the top silicon.

According to the embodiment of the invention, the periodic structure light absorption layer 300 and the doped region 400 formed by the multiplication layer 200, the charge layer 210, the quantum dot layer 310 and the cap layer 320 on the quantum dot layer are etched or etched to form a mesa, so as to form a waveguide layer and expose part of the top silicon 130, and then part of the top silicon 110 is etched by etching until part of the intermediate silicon dioxide buried layer 120 is exposed and the mesa is formed with the etched part of the top silicon, so that the exposed intermediate silicon dioxide buried layer region can be an electrical isolation region of the device. As shown in fig. 3 (d).

According to the embodiment of the invention, the doped region 400, the light absorption layer 300, the charge layer 210 and the multiplication layer 200 are etched by adopting a photoetching or dry etching method, the etching depth is 1800-1900 nm, and the waveguide layer can be rectangular and has the width of 6-8 μm.

According to embodiments of the present invention, electrical isolation regions are formed to separate devices from each other.

In step S206, an insulating dielectric layer 500 is formed on the middle silicon dioxide buried layer of a portion of the SOI substrate, the etched portion of the top silicon layer, and the doped region 400.

According to an embodiment of the present invention, preparing the insulating dielectric layer 500 may include: the insulating dielectric layer 500 is prepared by depositing on a portion of the top layer silicon 130 and on the doped region 400 using a plasma enhanced chemical vapor deposition process. As shown in fig. 3 (e).

According to an embodiment of the present invention, the material of the insulating dielectric layer 500 may include, but is not limited to: silicon dioxide or silicon nitride; the thickness of the insulating dielectric layer 500 may be 800 to 1300 nm.

According to the embodiment of the invention, the insulating medium layer can be used for protecting the electrical isolation of the material covered in the avalanche photodetector from the external environment, and avoiding the pollution of foreign objects or the damage of external force and the like.

In step S207, an electrode window is formed on the insulating dielectric layer 500.

In step S208, an n-electrode and a p-electrode 610 are respectively formed in the electrode windows.

According to an embodiment of the present invention, preparing the electrode window may include: an electrode window is formed on the insulating dielectric layer 500 by dry etching using the photoresist as a mask. As shown in fig. 3 (f).

According to an embodiment of the present invention, the n-electrode includes a first n-electrode 620 and a second n-electrode 630, and the n-electrode and the p-electrode 610 are respectively fabricated in the electrode windows, including: a p electrode 610 is manufactured in an electrode window formed on the insulating medium layer 500 covering the doping region 400; a first n-electrode 620 and a second n-electrode 630 are respectively formed in electrode windows formed in the insulating dielectric layer 500 covering a portion of the top silicon layer 130. As shown in fig. 3 (g).

According to the embodiment of the present invention, the p-electrode 610 is disposed at the edge of the doped region 400, not at the center of the doped region 400, to reduce the absorption of light by the metal.

According to the embodiment of the present invention, the p-electrode 610 is electrically connected to the doped region 400 to realize ohmic contact; the first n-electrode 620 and the second n-electrode 630 are respectively located on two sides of the top silicon 130, and are electrically connected with the top silicon 130 to realize ohmic contact.

According to the embodiment of the invention, the self-covering multilayer quantum dot material is adopted as the light absorption layer, so that dislocation generated in germanium-silicon heteroepitaxy is reduced, dark count of the device is reduced, meanwhile, a waveguide coupling mode is adopted, so that incident light is transversely absorbed in the avalanche photodetector, the absorption of light is enhanced by adjusting the length of the waveguide, the detection efficiency of the device is improved, and the detection and avalanche amplification of optical signals are realized.

It should also be noted that directional terms, such as "upper", "lower", "front", "rear", "left", "right", etc., used in the embodiments are only directions referring to the drawings, and are not intended to limit the scope of the present invention. Throughout the drawings, like elements are represented by like or similar reference numerals. Conventional structures or constructions will be omitted when they may obscure the understanding of the present invention.

And the shapes and sizes of the respective components in the drawings do not reflect actual sizes and proportions, but merely illustrate contents of the embodiments of the present invention. Furthermore, the word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the invention and aiding in the understanding of one or more of the various inventive aspects. However, the method of the invention should not be construed to reflect the intent: that the invention as claimed requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing inventive embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

The above embodiments are provided to further explain the objects, technical solutions and advantages of the present invention in detail, and it should be understood that the above embodiments are only examples of the present invention and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.