Evanescent coupling type germanium-silicon photoelectric detector based on sub-wavelength grating

Abstract

The invention discloses an evanescent coupling type germanium-silicon photoelectric detector based on a sub-wavelength grating, and belongs to the technical field of photoelectric detection. The germanium-silicon photoelectric detector comprises a silicon slab waveguide layer, a ridge waveguide layer, a germanium absorption region, an upper cladding and an electrode, the ridge waveguide layer comprises a first ridge waveguide area, a second ridge waveguide area, a third ridge waveguide area and a fourth ridge waveguide area, and the fourth ridge waveguide area is used for receiving optical signals and transmitting the optical signals to the third ridge waveguide area and the germanium absorption area; the waveguide of the third ridge waveguide region adopts a sub-wavelength grating with a gradually-changed size to regulate and control the coupling characteristic of light, so that the light can be gradually received by the first germanium absorption region and the second germanium absorption region on the two sides in the propagation process, and absorption light fields can be uniformly distributed in the germanium absorption regions. Signal distortion caused by the fact that the front end of germanium enters a saturation state under high-power incidence can be effectively avoided. The invention further provides a preparation method of the germanium-silicon photoelectric detector, the preparation method is compatible with the COMS technology, and the process complexity and the production cost are reduced.

Description

Technical Field

[0001] The present application relates to the technical field of photodetectors, and particularly to an evanescent coupling type germanium-silicon photodetector based on a subwavelength grating. Background Art

[0002] All along, analog optical communication and microwave photonics have been widely applied in the fields of military radar and wireless communication. Photoelectric communication, analog photonics, and microwave photonics highly require photodetectors with large bandwidth, high saturation power, and high linearity. In the past decade or so, various large-bandwidth high-power detectors have been proposed and verified on the III-V integration platform, such as uni-traveling-carrier photodetectors (UTC PDs) and modified uni-traveling-carrier photodetectors (MUTC PDs). However, these devices have problems such as high cost, poor thermal conductivity, and difficulty in realizing large-scale integration. In contrast, silicon-based devices with low cost, high thermal conductivity, and easy compatibility with complementary metal-oxide-semiconductor (CMOS) technology are possible solutions to solve these problems. Therefore, large-bandwidth high-power detectors based on silicon-based integration platforms have also attracted the attention of many researchers.

[0003] In silicon photonics, waveguide-coupled germanium-silicon detectors are a widely used device. However, in current waveguide-coupled germanium-silicon photodetectors, most of the absorption of optical energy occurs in the first few micrometers of the detector during single-end input. Therefore, the optical field distribution in the germanium region is non-uniform. Due to the carrier shielding effect, this is not conducive to carrier transport. Especially in the case of high-power signal input, the germanium absorption region is prone to saturated absorption, resulting in signal distortion and information decoding errors.

[0004] In view of this, proposing a germanium-silicon photodetector with high saturation power is of great significance for the application expansion of silicon photonics. Summary of the Invention

[0005] In the prior art, waveguide-type germanium-silicon photodetectors are prone to enter a saturated state under high-power incident light, resulting in signal distortion. In view of the deficiencies and improvement requirements of the prior art, the present application provides a germanium-silicon photodetector with high saturation power based on a subwavelength grating. By regulating parameters of the subwavelength grating waveguide and the spacing between the grating waveguide and the germanium absorption region, etc., the present application realizes a uniform distribution of the optical absorption field in germanium in the optical signal propagation direction, significantly reduces the density of photo-generated carriers at the front end of germanium, and avoids its entering the saturated state under high power, thereby achieving high saturation power.

[0006] To achieve the above object, the present application provides the following technical solutions:

[0007] In a first aspect, the present application provides a germanium-silicon photodetector, which includes:

[0008] Silicon substrate;

[0009] Buried oxide layer, the buried oxide layer is disposed on the silicon substrate;

[0010] Silicon planar waveguide layer, the silicon planar waveguide layer is disposed on the buried oxide layer;

[0011] Ridge waveguide layer, the ridge waveguide layer is disposed on the silicon planar waveguide layer, the ridge waveguide layer includes a first ridge waveguide region, a second ridge waveguide region, a third ridge waveguide region, and a fourth ridge waveguide region; wherein, the first ridge waveguide region and the second ridge waveguide region are dispersed at both ends of the third ridge waveguide region, and the fourth ridge waveguide region is horizontally connected to the third ridge waveguide region;

[0012] Germanium absorption region, the germanium absorption region is located on the ridge waveguide region;

[0013] Upper cladding layer, the upper cladding layer is located on the silicon planar waveguide layer and covers the ridge waveguide layer and the germanium layer;

[0014] Electrodes, the electrodes include a first electrode and a second electrode, the first electrode forms an ohmic contact with the first ridge waveguide region and the second ridge waveguide region respectively, and the second electrode forms an ohmic contact with the germanium absorption region; the first electrode and the second electrode penetrate through the upper cladding layer.

[0015] Further, the germanium absorption region includes a first germanium absorption region and / or a second germanium absorption region, the first germanium absorption region is located on the first ridge waveguide region, and the second germanium absorption region is located on the second ridge waveguide.

[0016] Further, both the first ridge waveguide region and the second ridge waveguide region include a first doping region and a second doping region, and the doping concentration of the first doping region is greater than that of the second doping region.

[0017] Further, the first electrode forms an ohmic connection with the first doping region.

[0018] Further, the first germanium absorption region is located on the second doping region of the first ridge waveguide region, the second germanium absorption region is located on the second doping region of the second ridge waveguide region, and a third doping region is provided in both the first germanium absorption region and the second germanium absorption region, wherein the second electrode forms an ohmic contact with the third doping region.

[0019] Further, the materials of the buried oxide layer and the upper cladding layer are both silicon dioxide.

[0020] In a second aspect, the present application provides another germanium-silicon photodetector, which includes:

[0021] Silicon substrate;

[0022] A buried oxide layer, which is disposed on the silicon substrate;

[0023] A silicon slab waveguide layer, which is disposed on the buried oxide layer;

[0024] A ridge waveguide layer, which is disposed on the silicon slab waveguide layer. The ridge waveguide layer includes a first ridge waveguide region, a third ridge waveguide region, and a fourth ridge waveguide region. Among them, the first ridge waveguide region is located on one side of the third ridge waveguide region, and the fourth ridge waveguide region is horizontally connected to the third ridge waveguide region;

[0025] A germanium absorption region, which is located on the first ridge waveguide region;

[0026] An upper cladding layer, which is located on the silicon slab waveguide layer and covers the ridge waveguide layer and the germanium layer;

[0027] Electrodes, which include a first electrode and a second electrode. The first electrode forms an ohmic contact with the first ridge waveguide region, and the second electrode forms an ohmic contact with the germanium absorption region. The first electrode and the second electrode penetrate through the upper cladding layer.

[0028] Further, the first ridge waveguide region includes a first doping region and a second doping region. The doping concentration of the first doping region is greater than that of the second doping region, and the first electrode forms an ohmic connection with the first doping region.

[0029] Further, the germanium absorption region is located on the second doping region of the first ridge waveguide region, and the germanium absorption region is provided with a third doping region, wherein the second electrode forms an ohmic contact with the third doping region.

[0030] Further, the materials of the buried oxide layer and the upper cladding layer are both silicon dioxide.

[0031] In a third aspect, the present application provides a method for manufacturing the foregoing germanium-silicon photodetector, including the following steps:

[0032] Etch the top silicon layer of the SOI to form a silicon slab waveguide layer and a ridge waveguide layer located on the silicon slab waveguide layer. The ridge waveguide layer includes a first ridge waveguide region, a second ridge waveguide region, a third ridge waveguide region, and a fourth ridge waveguide region;

[0033] Through processes such as photolithography and ion implantation doping, form an adjacently arranged first doping region and second doping region in the first ridge waveguide region and the second ridge waveguide region;

[0034] Form a germanium absorption region on the ridge waveguide layer, that is, form a first germanium absorption region on the second doping region in the first ridge waveguide region, and form a second germanium absorption region on the second doping region in the second ridge waveguide region;

[0035] Ion implantation doping is performed on the upper parts of the first germanium absorption region and the second germanium absorption region to form a third doped region;

[0036] Silica is filled on the silicon slab waveguide layer, the ridge waveguide layer and the germanium absorption region to form an upper cladding;

[0037] On the upper cladding, electrodes are fabricated by using a photolithography and etching process and the Lift off method. The electrodes include a first electrode and a second electrode. Among them, the first electrode forms an ohmic contact with the first doped region, and the second electrode forms an ohmic contact with the third doped region, and finally a germanium-silicon photodetector is obtained.

[0038] Further, the manufacturing processes of the silicon slab waveguide layer and the ridge waveguide layer include: first, a mask is prepared by using at least one of EBL, a step-and-repeat photolithography machine, laser direct writing, etc., and then obtained by using ICP and RIE dry etching methods.

[0039] Further, the germanium absorption region is prepared by at least one of magnetron sputtering, atomic layer deposition, and chemical vapor deposition.

[0040] Further, the electrodes are prepared by at least one of thermal evaporation, electron beam evaporation, magnetron sputtering, etc.

[0041] Further, the upper cladding is prepared by at least one of magnetron sputtering, atomic layer deposition, and chemical vapor deposition.

[0042] The technical solution provided by the embodiment of the present application, compared with the prior art, has at least the following beneficial effects:

[0043] 1. The germanium-silicon photodetector provided by the present application includes a first ridge waveguide region, a second ridge waveguide region, a third ridge waveguide region, and a fourth ridge waveguide region. The fourth ridge waveguide region is used to receive an optical signal and transmit it to the third ridge waveguide region, and is transmitted to the first germanium absorption region and the second germanium absorption region on the first ridge waveguide region and the second ridge waveguide region through the sub-wavelength grating waveguide of the third ridge waveguide region; the waveguide of the third ridge waveguide region adopts a sub-wavelength grating with a gradually changing size to regulate the optical coupling characteristics, so that the light can be gradually received by the first germanium absorption region and the second germanium absorption region on both sides during propagation, and there can be a uniformly distributed absorption optical field in the germanium absorption region, which can effectively avoid signal distortion caused by the front end of germanium entering the saturation state under high-power incidence.

[0044] 2. The germanium-silicon photodetector provided by the present application is fabricated on a SOI wafer, is compatible with COMS technology, and reduces the process complexity and production cost. Description of the Drawings

[0045] The present application will be further described in detail below in conjunction with the accompanying drawings and preferred embodiments. However, those skilled in the art will appreciate that these drawings are only drawn for the purpose of explaining the preferred embodiments and should not be construed as limiting the scope of the present application. In addition, unless otherwise specified, the drawings only schematically show the composition or structure of the described object and may include exaggerated displays, and the drawings are not necessarily drawn to scale.

[0046] Figure 1 Schematic perspective view of the first germanium-silicon photodetector provided by the embodiment of the present application;

[0047] Figure 2 Top view of the first germanium-silicon photodetector provided by the embodiment of the present application;

[0048] Figure 3 Side cross-sectional view of the first germanium-silicon photodetector provided by the embodiment of the present application along the A-A direction;

[0049] Figure 4 Top view of the second germanium-silicon photodetector provided by the embodiment of the present application;

[0050] Figure 5 Side cross-sectional view of the second germanium-silicon photodetector provided by the embodiment of the present application along the B-B direction;

[0051] Figure 6 Top view of the third ridge waveguide region structure provided by the embodiment of the present application, where a is the top view of the first sub-wavelength grating waveguide structure in the third ridge waveguide region, b is the top view of the second sub-wavelength grating waveguide structure in the third ridge waveguide region, and c is the top view of the third sub-wavelength grating waveguide structure in the third ridge waveguide region;

[0052] Figures 7a-7g Schematic diagram of the manufacturing process flow of the germanium-silicon photodetector provided by the embodiment of the present application;

[0053] Wherein, 1 is a silicon substrate, 2 is a buried oxide layer, 3 is a silicon slab waveguide layer (the top silicon layer of SOI in FIG. 7), 4 is a ridge waveguide layer, 41 is a first ridge waveguide region, 42 is a second ridge waveguide region, 43 is a third ridge waveguide region, 44 is a fourth ridge waveguide region, 5 is a germanium absorption region, 51 is a first germanium absorption region, 52 is a second germanium absorption region, 6 is an upper cladding layer, 7 is an electrode, 71 is a first electrode, and 72 is a second electrode. Detailed implementation manners

[0054] Other embodiments obtained by those skilled in the art without creative efforts shall fall within the scope of protection of the present application.

[0055] For a common single-end incident germanium-silicon photodetector, the optical signal energy will be concentrated at the front end of germanium and exponentially attenuated in the transmission direction. Therefore, in the case of high-power incidence, the front end of germanium is more likely to enter the saturation state, and the germanium at the back end has a low absorption and utilization rate of energy. An embodiment of the present application provides a germanium-silicon photodetector. The germanium-silicon photodetector regulates the coupling characteristics between the grating waveguide and the germanium absorption region through a subwavelength grating waveguide, so as to generate a uniformly distributed optical field in the germanium absorption region in the optical transmission direction, improve the efficiency of the germanium absorption region to absorb optical signals, and enable the germanium absorption region to absorb strong optical energy as a whole even in the case of high-power incidence, avoiding signal distortion caused by the front end of germanium entering the saturation state too quickly due to the overly strong absorption of the optical field.

[0056] Based on this, an embodiment of the present application provides a subwavelength grating-based evanescent coupling germanium-silicon photodetector, as Figure 1 shown, which includes a silicon substrate 1, a buried oxide layer 2, a silicon slab waveguide layer 3, a ridge waveguide layer 4, a germanium absorption region 5, an upper cladding layer 6, and electrodes 7; as Figure 2 、 Figure 3 shown, the buried oxide layer 2 is disposed on the silicon substrate 1; the silicon slab waveguide layer 3 is disposed on the buried oxide layer 2; the ridge waveguide layer 4 is disposed on the silicon slab waveguide layer 3. The ridge waveguide layer 4 includes a first ridge waveguide region 41, a second ridge waveguide region 42, a third ridge waveguide region 43, and a fourth ridge waveguide region 44. Among them, the first ridge waveguide region 41 and the second ridge waveguide region 42 are dispersed at both ends of the third ridge waveguide region 43. The third ridge waveguide region 43 is a subwavelength grating waveguide, and the fourth ridge waveguide region 44 is horizontally connected to the third ridge waveguide region 43; the germanium absorption region 5 is located on the ridge waveguide region 4; the upper cladding layer 6 is located on the silicon slab waveguide layer 3 and covers the ridge waveguide layer 4 and the germanium absorption region 5; the electrodes 7 include a first electrode 71 and a second electrode 72. The first electrode 71 forms ohmic contacts with the first ridge waveguide region 41 and the second ridge waveguide region 42 respectively, and the second electrode 72 forms an ohmic contact with the germanium absorption region 5; the first electrode 71 and the second electrode 72 penetrate through the upper cladding layer 6.

[0057] In some embodiments, there is only one germanium absorption region 5, that is, the germanium absorption region 5 is located on the first ridge waveguide region 41 or the second ridge waveguide region 42; the fourth ridge waveguide region 44 receives an optical signal and transmits it to the third ridge waveguide region 43, and transmits it to the germanium absorption region 5 on the first ridge waveguide region 41 (or the second ridge waveguide region 42) through the subwavelength grating waveguide of the third ridge waveguide region 43.

[0058] In the embodiments of the present application, the shape of the germanium absorption region 5 is not specifically limited. In some embodiments, the germanium absorption region 5 may be a rectangle, a cone, a trapezoid, or an irregular shape, as long as the germanium absorption region 5 can perform the function of receiving optical signals.

[0059] In some embodiments, the germanium absorption region 5 includes a first germanium absorption region 51 and a second germanium absorption region 52. The first germanium absorption region 51 is located on the first ridge waveguide region 41, and the second germanium absorption region 52 is located on the second ridge waveguide 42. The fourth ridge waveguide region 44 receives an optical signal and transmits it to the third ridge waveguide region 43, and then transmits it to the first germanium absorption region 51 and the second germanium absorption region 52 on the first ridge waveguide region 41 and the second ridge waveguide region 42 through the sub-wavelength grating waveguide of the third ridge waveguide region 43.

[0060] In the embodiments of the present application, the first ridge waveguide region 41 includes a first doping region 411 and a second doping region 412, and the second ridge waveguide region 42 also includes a first doping region 421 and a second doping region 422. The doping concentration of the first doping region 411 (421) is greater than that of the second doping region 412 (422).

[0061] In the embodiments of the present application, the first electrode 71 forms an ohmic connection with the first doping region 411 and the first doping region 421.

[0062] In some embodiments, the first germanium absorption region 51 is located on the second doping region 412 of the first ridge waveguide region 41, and the second germanium absorption region 52 is located on the second doping region 422 of the second ridge waveguide region 42. A third doping region 511 (521) is provided in both the first germanium absorption region 51 and the second germanium absorption region 52. The second electrode 72 forms an ohmic contact with the third doping region 511 and the third doping region 521. The doping type of the third doping region 511 (521) is opposite to that of the first doping region 411 (421) and the second doping region 412 (422) of the ridge waveguide layer 4.

[0063] In some embodiments, the first electrode 71 is grounded, and the second electrode 72 is connected to the signal terminal. An external electric field is formed by applying an external voltage to extract the photo-generated carriers in the germanium absorption region 5.

[0064] In the embodiments of the present application, the materials of the buried oxide layer 2 and the upper cladding layer 6 are both silicon dioxide.

[0065] In the embodiments of the present application, the sub-wavelength grating waveguide structure of the third ridge waveguide region 43 has multiple implementation manners. In some embodiments, as the first implementation manner, such as Figure 6As shown in a, while keeping the width W1 of the outermost waveguide constant, grooves of different sizes are etched inward. The size parameters of the grooves include length L1 and width L2. As the second embodiment, as Figure 6 shown in b, while keeping the width W2 of the inner waveguide constant, bumps of different sizes are distributed on the outside. The size parameters of the bumps include length L3 and width L4. As the third embodiment, as Figure 6 shown in c, it can also be a sub-wavelength grating waveguide formed by other geometric arrangement arrays. By adjusting the parameters of the sub-wavelength grating and the spacing between the grating waveguide and the germanium absorption region 5, etc., the coupling characteristics between the ridge waveguide layer 4 and the germanium absorption region 5 are regulated. The sub-wavelength grating waveguide in the third ridge waveguide region 43 can be divided into multiple waveguide regions in the optical signal transmission direction. The gratings in each waveguide region are uniformly arranged, and the grating size parameters in different waveguide regions can be the same or different.

[0066] Based on this, the embodiment of the present application also provides another germanium-silicon photodetector. Compared with the germanium-silicon photodetector provided in the foregoing embodiment, as Figure 4 、 Figure 5 shown, the germanium-silicon photodetector in the embodiment of the present application has only one ridge waveguide region 4 and the corresponding germanium absorption region 5 structure, that is, the second ridge waveguide region 42 and the corresponding second germanium absorption region 52 structure are missing. Specifically, it includes a silicon substrate 1, a buried oxide layer 2, a silicon slab waveguide layer 3, a ridge waveguide layer 4, a germanium absorption region 5, an upper cladding layer 6, and electrodes 7; the buried oxide layer 2 is disposed on the silicon substrate 1; the silicon slab waveguide layer 3 is disposed on the buried oxide layer 2; the ridge waveguide layer 4 is disposed on the silicon slab waveguide layer 3. The ridge waveguide layer 4 includes a first ridge waveguide region 41, a third ridge waveguide region 43, and a fourth ridge waveguide region 44; wherein, the first ridge waveguide region 41 is located on one side of the third ridge waveguide region 43, and the fourth ridge waveguide region 44 is horizontally connected to the third ridge waveguide region 43; the germanium absorption region 5 is located on the first ridge waveguide region 41; the upper cladding layer 6 is located on the silicon slab waveguide layer 3 and covers the ridge waveguide layer 4 and the germanium absorption region 5; the electrodes 7 include a first electrode 71 and a second electrode 72. The first electrode 71 forms an ohmic contact with the first ridge waveguide region 41, and the second electrode 72 forms an ohmic contact with the germanium absorption region 5; the first electrode 71 and the second electrode 72 penetrate through the upper cladding layer.

[0067] In the embodiment of the present application, the first ridge waveguide region 41 includes a first doping region 411 and a second doping region 412. The doping concentration of the first doping region 411 is greater than that of the second doping region 412, and the first electrode 71 forms an ohmic connection with the first doping region 411.

[0068] In the embodiment of the present application, the germanium absorption region 5 is located on the second doping region 412 of the first ridge waveguide region 41. The germanium absorption region 5 is provided with a third doping region 511, and the second electrode 72 forms an ohmic contact with the third doping region 511.

[0069] In some embodiments, the ground terminal of the first electrode 71 and the signal terminal of the second electrode 72 are connected. By applying an external voltage to form an external electric field, the photo-generated carriers in the germanium absorption region 5 are extracted.

[0070] In the embodiment of the present application, the materials of the buried oxide layer 2 and the upper cladding layer 6 are both silicon dioxide.

[0071] Based on this, the embodiment of the present application further provides a preparation method of a germanium-silicon photodetector. Now, in combination with Figures 7a-7g make a further description of this preparation method.

[0072] The preparation method of the germanium-silicon photodetector provided by the embodiment of the present application specifically includes the following steps:

[0073] The first step: As Figure 7a shown, provide an SOI substrate, which sequentially includes a silicon substrate 1, a buried oxide layer 2, and a top silicon layer 3 from bottom to top;

[0074] The second step: As Figure 7b shown, etch the top silicon layer 3 of the SOI to form a silicon slab waveguide layer 3 (with the same label as the top silicon layer) and a ridge waveguide layer 4 located on the silicon slab waveguide layer 3. Specifically, the ridge waveguide layer 4 includes a first ridge waveguide region 41, a second ridge waveguide region 42, a third ridge waveguide region 43, and a fourth ridge waveguide region 44 (the structural schematic diagram of the 4th ridge waveguide region 44 can be referred to Figure 2 );

[0075] The third step: As Figure 7c shown, through processes such as photolithography and ion implantation doping, adjacent first doping regions 411 (421) and second doping regions 412 (422) are formed in the first ridge waveguide region 41 and the second ridge waveguide region 42;

[0076] The fourth step: As Figure 7d shown, form a germanium absorption region 5 on the ridge waveguide layer 4, that is, form a first germanium absorption region 51 on the second doping region 412 in the first ridge waveguide region 41, and form a second germanium absorption region 52 on the second doping region 422 in the second ridge waveguide region 42;

[0077] The fifth step: As Figure 7e shown, perform ion implantation doping on the upper parts of the first germanium absorption region 51 and the second germanium absorption region 52 to form third doping regions 511 (521);

[0078] Step 6: As shown in Figure 7f Figure 7f , a silica is filled on the silicon slab waveguide layer 3, the ridge waveguide layer 4, and the germanium absorption region 5 to form an upper cladding layer 6;

[0079] Step 7: As shown in Figure 7g Figure 7g , on the upper cladding layer 6, electrodes 7 are fabricated by using a photolithography etching process and a Lift off method. The electrodes include a first electrode 71 and a second electrode 72. Among them, the first electrode 71 forms an ohmic contact with the first doped region 411(421), and the second electrode 72 forms an ohmic contact with the third doped region 511(521), and finally a germanium-silicon photodetector is obtained.

[0080] In some embodiments, the manufacturing processes of the silicon slab waveguide layer 3 and the ridge waveguide layer 4 include: first, a mask is fabricated by using at least one of electron beam lithography (EBL), a step-and-repeat photolithography machine, and laser direct writing, and then the silicon slab waveguide layer 3 and the ridge waveguide layer 4 are obtained by using an inductively coupled plasma etching method (ICP) and a reactive ion etching (RIE) dry etching method.

[0081] Furthermore, the germanium absorption region is obtained by at least one of magnetron sputtering, atomic layer deposition, and chemical vapor deposition.

[0082] In some embodiments, the electrodes 7 are obtained by at least one of thermal evaporation, electron beam evaporation, and magnetron sputtering.

[0083] In some embodiments, the upper cladding layer 6 is obtained by at least one of magnetron sputtering, atomic layer deposition, and chemical vapor deposition.

[0084] In summary, the germanium-silicon photodetector provided by the embodiments of the present application can regulate the coupling characteristics between the grating waveguide and the germanium absorption region through a sub-wavelength grating waveguide, so that there is a uniformly distributed optical field in the germanium absorption layer in the optical transmission direction, improving the efficiency of the germanium absorption layer for absorbing optical signals. In the case of high-power incidence, the germanium absorption layer can also absorb strong optical energy as a whole, avoiding signal distortion caused by the germanium front-end absorption optical field being too strong and quickly entering a saturation state.

[0085] The above has introduced the present application in detail. Specific examples are used in the present application to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the present application and its core idea. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A germanium-silicon photodetector, characterized in that Comprising: A silicon substrate; A buried oxide layer disposed on the silicon substrate; A silicon slab waveguide layer disposed on the buried oxide layer; A ridge waveguide layer disposed on the silicon slab waveguide layer, the ridge waveguide layer including a first ridge waveguide region, a second ridge waveguide region, a third ridge waveguide region, and a fourth ridge waveguide region; wherein, the first ridge waveguide region and the second ridge waveguide region are dispersed at both ends of the third ridge waveguide region, and the fourth ridge waveguide region is horizontally connected to the third ridge waveguide region; A germanium absorption region located on the ridge waveguide region; An upper cladding layer located on the silicon slab waveguide layer and covering the ridge waveguide layer and the germanium layer; Electrodes, the electrodes including a first electrode and a second electrode, the first electrode forming ohmic contacts with the first ridge waveguide region and the second ridge waveguide region respectively, and the second electrode forming an ohmic contact with the germanium absorption region; the first electrode and the second electrode penetrate through the upper cladding layer.

2. The germanium-silicon photodetector according to claim 1, wherein The germanium absorption region includes a first germanium absorption region and / or a second germanium absorption region, the first germanium absorption region is located on the first ridge waveguide region, and the second germanium absorption region is located on the second ridge waveguide.

3. The germanium-silicon photodetector according to claim 1, characterized in that, Both the first ridge waveguide region and the second ridge waveguide region include a first doped region and a second doped region, the doping concentration of the first doped region is greater than that of the second doped region, and the first electrode forms an ohmic connection with the first doped region.

4. The germanium-silicon photodetector according to claim 3, characterized in that, The first germanium absorption region is located on the second doped region of the first ridge waveguide region, the second germanium absorption region is located on the second doped region of the second ridge waveguide region, and a third doped region is provided in both the first germanium absorption region and the second germanium absorption region, wherein the second electrode forms an ohmic contact with the third doped region.

5. The germanium-silicon photodetector according to claim 1, characterized in that, The materials of the buried oxide layer and the upper cladding layer are both silicon dioxide.

6. A germanium-silicon photodetector, characterized in that, Comprising: A silicon substrate; A buried oxide layer disposed on the silicon substrate; A silicon slab waveguide layer disposed on the buried oxide layer; A ridge waveguide layer disposed on the silicon slab waveguide layer, the ridge waveguide layer including a first ridge waveguide region, a third ridge waveguide region, and a fourth ridge waveguide region; wherein, the first ridge waveguide region is located on one side of the third ridge waveguide region, and the fourth ridge waveguide region is horizontally connected to the third ridge waveguide region; A germanium absorption region located on the first ridge waveguide region; An upper cladding layer located on the silicon slab waveguide layer and covering the ridge waveguide layer and the germanium layer; Electrodes, the electrodes including a first electrode and a second electrode, the first electrode forming an ohmic contact with the first ridge waveguide region, and the second electrode forming an ohmic contact with the germanium absorption region; the first electrode and the second electrode penetrate through the upper cladding layer; The first ridge waveguide region includes a first doped region and a second doped region, the doping concentration of the first doped region is greater than that of the second doped region, and the first electrode forms an ohmic contact with the first doped region; the germanium absorption region is located on the second doped region of the first ridge waveguide region, and the germanium absorption region is provided with a third doped region, wherein the second electrode forms an ohmic contact with the third doped region; the buried oxide layer and the upper cladding material are both silicon dioxide.

7. A preparation method of a germanium-silicon photodetector, characterized in that, Including the following steps: Etch the top silicon layer of the SOI to form a silicon slab waveguide layer and a ridge waveguide layer located on the silicon slab waveguide layer. The ridge waveguide layer includes a first ridge waveguide region, a second ridge waveguide region, a third ridge waveguide region, and a fourth ridge waveguide region; Through processes such as photolithography and ion implantation doping, adjacent first and second doped regions are formed in the first ridge waveguide region and the second ridge waveguide region; A germanium absorption region is formed on the ridge waveguide layer, that is, a first germanium absorption region is formed on the second doped region in the first ridge waveguide region, and a second germanium absorption region is formed on the second doped region in the second ridge waveguide region; Ion implantation doping is performed on the upper parts of the first germanium absorption region and the second germanium absorption region to form a third doped region; Silicon dioxide is filled on the silicon slab waveguide layer, the ridge waveguide layer, and the germanium absorption region to form an upper cladding; On the upper cladding, electrodes are prepared by using an exposure etching process and a Lift off method. The electrodes include a first electrode and a second electrode. Among them, the first electrode forms an ohmic contact with the first doped region, and the second electrode forms an ohmic contact with the third doped region, and finally a germanium-silicon photodetector is obtained.

8. The preparation method according to claim 7, characterized in that, The manufacturing process of the silicon slab waveguide layer and the ridge waveguide layer includes: first, a mask is prepared by using at least one of EBL, a step-and-repeat lithography machine, and laser direct writing, and then obtained by using ICP and RIE dry etching methods.

9. The preparation method according to claim 7, characterized in that, The germanium absorption region and the upper cladding are both prepared by using at least one of magnetron sputtering, atomic layer deposition, and chemical vapor deposition.

10. The preparation method according to claim 7, characterized in that, The electrodes are prepared by using at least one of thermal evaporation, electron beam evaporation, and magnetron sputtering.

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