A germanium-silicon hybrid photodetector device with high-density integration

Abstract

The present invention discloses a germanium-silicon hybrid optical detection device that can be highly integrated on a chip, and this device has both the functions of optical signal transmission and optical power detection. The device includes a silicon transmission waveguide and a germanium absorption layer: among them, there is a stable distribution of the light field strength in the silicon transmission waveguide; the germanium absorption layer is located above the region with weak light field distribution, and by absorbing the optical signal in the region with weak light field distribution, it converts it into an electrical signal to realize the characterization of the optical power transmitted in the waveguide; the remaining optical signals still transmit in the silicon waveguide. The germanium-silicon hybrid optical detection device realized by the present invention has the advantages of small size, low transmission loss, low detectable power, low reflectivity, and compatibility with the standard CMOS process, and is suitable for high-density integration in large-scale optical interconnection systems to realize real-time monitoring of the power at multiple locations, and has broad application prospects in the fields of optical communication, microwave photonics, etc.

Description

Technical Field

[0001] The present invention relates to the field of optoelectronic detection technology, and particularly to a germanium-silicon hybrid optical detection device capable of high-density integration. Background Art

[0002] With the development of silicon photonics technology, the requirements for the integration density of silicon photonics chips in fields such as microwave photonics, optical computing, and optical communication are getting higher and higher. In a silicon photonics integrated chip, it is necessary to detect the optical power at important system nodes to judge the working state of the system, and at the same time, have as little impact on the transmission of optical signals as possible. However, current photodetectors focus more on power detection performance and are more suitable for the receiving end of the system, that is, all optical power is converted into electrical signals, and the signal transmission function cannot be realized. To achieve the power detection and transmission functions in the system, the commonly used method at present is to use a small proportion coupler to couple out a part of the optical power from the system, and then use a photodetector to detect the coupled optical power, and the uncoupled optical power continues to be transmitted in the system. However, this method has problems such as large size, large transmission loss, high reflectivity, and high minimum detection power, which limit its application in large-scale integrated optical circuits. Summary of the Invention

[0003] In view of this, an embodiment of the present invention provides a germanium-silicon hybrid optical detection device capable of high-density integration to solve at least one problem in the background art.

[0004] To achieve the above object, the technical solution of the present invention is realized as follows:

[0005] An embodiment of the present invention provides a germanium-silicon hybrid optical detection device capable of high-density integration, including: a silicon transmission waveguide and a germanium absorption layer located thereon; wherein,

[0006] The silicon transmission waveguide includes a first waveguide region, a second waveguide region, a third waveguide region, a fourth waveguide region, and a fifth waveguide region arranged in sequence along the optical signal propagation direction;

[0007] In the first waveguide region, the waveguide width becomes wider or remains unchanged along the propagation direction;

[0008] In the second waveguide region, the waveguide width at each location is greater than or equal to that of the first waveguide region and the fifth waveguide region;

[0009] The third waveguide region is a ridge waveguide, and its waveguide width is greater than that of the other four waveguide regions; the third waveguide region includes a planar waveguide layer and a ridge waveguide layer in the vertical direction, wherein the height of the ridge waveguide layer is greater than that of the planar waveguide layer; the ridge waveguide layer of the third waveguide region includes two or more ridge waveguide regions arranged at intervals, and the edge interval of each ridge waveguide region is greater than or equal to 1um to ensure that no energy exchange occurs between the ridge waveguides;

[0010] When a light signal is transmitted, there is a stable spatial light field intensity distribution in the third waveguide region described above;

[0011] The waveguide width at each location in the fourth waveguide region is greater than or equal to that of the first waveguide region and the fifth waveguide region;

[0012] In the fifth waveguide region, the waveguide width narrows or remains unchanged along the propagation direction;

[0013] The germanium absorption layer described above is located above the weak light field distribution region in the third waveguide region, and its width is less than the widths of the second waveguide region and the fourth waveguide region; the length of the germanium absorption layer is less than or equal to the length of the third waveguide region.

[0014] In the above solution, in the first waveguide region and the fifth waveguide region, the light signal is transmitted in the fundamental mode, and multiple optical wave modes are supported in both the second waveguide region and the fourth waveguide region structures;

[0015] In the above solution, the widths of the second waveguide region and the fourth waveguide region can be the same everywhere or not necessarily the same everywhere; the two waveguide regions can be designed using an optimization algorithm to reduce the reflection caused by the germanium absorption layer above the third waveguide region and to make there be a stable spatial light field intensity distribution in the third waveguide region.

[0016] In the above solution, it further includes: ion doping and an electrode structure; the ion doping and the electrode structure include a horizontal mode and a vertical mode according to the distribution of the germanium absorption region; the electrode structure includes a positive electrode and a negative electrode;

[0017] In the above solution, for the horizontal-mode germanium-silicon hybrid photodetector, there is only one germanium absorption region above the third waveguide region, and the electrical signal characterizing the optical transmission power is the electrical signal generated by the germanium absorption layer absorbing the optical signal; for the vertical-mode germanium-silicon hybrid photodetector, there is one or more germanium absorption regions above the third waveguide region, and the electrical signal characterizing the optical transmission power is the sum of the electrical signals generated by any germanium absorption region absorbing the optical signal;

[0018] In the above solution, for the horizontal-mode germanium-silicon hybrid photodetector, P (or N) ion heavy doping, P (or N) ion light doping, no doping, N (or P) ion light doping, and N (or P) ion heavy doping are sequentially performed in the third waveguide region along the direction perpendicular to the optical signal propagation direction; the ion concentration in the heavy doping region is greater than that in the light doping region; for the vertical-mode germanium-silicon hybrid photodetector, P ions are doped in the third waveguide region, and N ions are doped at the top of the germanium absorption layer;

[0019] In the above solution, the positive electrode of the horizontally-oriented germanium-silicon hybrid photodetector is electrically connected to the P-ion heavily doped region, and the negative electrode is electrically connected to the N-ion heavily doped region; the positive electrode of the vertically-oriented germanium-silicon hybrid photodetector is electrically connected to the top of the germanium absorption layer, and the negative electrode is electrically connected to both ends of the third waveguide region.

[0020] An embodiment of the present invention provides a germanium-silicon hybrid optical detection device capable of high-density integration, which is characterized by including a silicon transmission waveguide and a germanium absorption layer located thereon; wherein the silicon transmission waveguide refers to the transmission waveguide of the optical signal; the silicon transmission waveguide includes a first waveguide region for the input optical signal, second, third, and fourth waveguide regions for signal transmission, and a fifth waveguide region for the output optical signal; there is a stable spatial optical field strength distribution in the third waveguide region during the transmission of the optical signal; there is one or more germanium absorption layers above the weak optical field region; the germanium absorption layer absorbs the optical signal from the silicon transmission waveguide and converts the photons of the absorbed optical signal into photo-generated carriers, thereby converting the optical signal into an electrical signal to characterize the optical signal power in the waveguide; subsequently, the optical signal is regulated and transmitted through the fourth waveguide region to form a low-loss and stable-transmission optical field, and finally the optical signal is output through the fifth waveguide region. In this process, low-loss and stable transmission of the optical signal is achieved, and at the same time, photocurrent information capable of reflecting the power of the transmitted optical signal is obtained. The second waveguide region and the fourth waveguide region can use an optimization algorithm to design the waveguide structure to reduce the reflection and loss caused by the germanium absorption layer, further improving the device performance. Description of the Drawings

[0021] Figure 1 Is a top view of a germanium-silicon hybrid optical detection device capable of high-density integration in the related art;

[0022] Figure 2 Is a side cross-sectional view of a germanium-silicon hybrid optical detection device capable of high-density integration in the related art;

[0023] Figure 3 Is a top view of the germanium-silicon hybrid optical detection device provided in Embodiment 1 of the present invention;

[0024] Figure 4 Is a top view of the third waveguide region of the germanium-silicon hybrid optical detection device provided in Embodiment 1 of the present invention;

[0025] Figure 5 Is a side cross-sectional view of the germanium-silicon hybrid optical detection device provided in Embodiment 1 and Embodiment 2 of the present invention;

[0026] Figure 6 Is a light field distribution diagram of the germanium-silicon hybrid optical detection device provided in Embodiment 1 of the present invention;

[0027] Figure 7 Top view of the germanium-silicon hybrid photodetector capable of high-density integration provided in the second embodiment and the third example of the present invention;

[0028] Figure 8 Side cross-sectional view of the germanium-silicon hybrid photodetector capable of high-density integration provided in the third embodiment of the present invention;

[0029] Figure 9 Top view of the germanium-silicon hybrid photodetector capable of high-density integration provided in the fourth embodiment of the present invention;

[0030] Figure 10 Side cross-sectional view of the germanium-silicon hybrid photodetector capable of high-density integration provided in the fourth embodiment of the present invention;

[0031] Figure 11 Optical field distribution diagram of the germanium-silicon hybrid photodetector capable of high-density integration provided in the fourth embodiment of the present invention;

[0032] Description of reference numerals:

[0033] Silicon transmission waveguide — 100; First waveguide region — 110; Second waveguide region — 120; Third waveguide region — 130; Fourth waveguide region — 140; Fifth waveguide region — 140; Doped waveguide 1 — 131; Transmission waveguide — 132; Doped waveguide 2 — 133; Ridge waveguide layer — 134; Planar waveguide layer — 135;

[0034] Germanium absorption layer — 200; First germanium absorption layer — 201; Second germanium absorption layer — 202;

[0035] Electrode — 300; Positive electrode — 301; Negative electrode — 302;

[0036] P ion heavy doping — 401; P ion light doping — 402; Undoped — 403; N ion light doping — 404; N ion heavy doping — 405; P doping — 406; N doping — 407;

[0037] Weak optical field region — 501; Self-imaging position — 502; Detailed implementation manners

[0038] Figure 1 Top view of a germanium-silicon hybrid photodetector capable of on-chip high-density integration in the related art, Figure 2 a, Figure 2 b is a cross-sectional view of a germanium-silicon hybrid photodetector capable of on-chip high-density integration in the related art. It should be noted that, Figure 2 is a cross-sectional view along the Figure 1 dashed line direction inFigure 1 As shown, in the related art, the silicon transmission waveguide 100 refers to the transmission waveguide for optical signals; the silicon transmission waveguide 100 includes a first waveguide region 110 for optical input signals, second, third, and fourth waveguide regions 140 for signal transmission, and a fifth waveguide region 150 for optical signal output; during the optical signal transmission process, there is one or more weak optical field regions 501 in the third waveguide region 130, and one or more germanium absorption layers 200 are formed above the weak optical field regions 501; the germanium absorption layer 200 absorbs the optical signals from the silicon transmission waveguide 100 and converts the photons of the absorbed optical signals into photo-generated carriers, thereby converting the optical signals into electrical signals to characterize the optical signal power in the waveguide; subsequently, the optical signals are regulated and transmitted through the fourth waveguide region 140 to form a low-loss and stable-transmission optical field, and finally the optical signals are output through the fifth waveguide region 150. In this process, low-loss and stable transmission of optical signals is achieved, and at the same time, photocurrent information that can reflect the power of the transmitted optical signals is obtained.

[0039] Based on this, the following technical solutions of the embodiments of the present invention are proposed:

[0040] See Figure 3 、 Figure 4 、 Figure 5 、 Figure 6 ,Embodiments of the present invention provide a germanium-silicon hybrid photodetector that can be highly integrated on a chip, including a silicon transmission waveguide 100 and a germanium absorption layer 200 located thereon; wherein the silicon transmission waveguide 100 includes a first waveguide region 110, a second waveguide region 120, a third waveguide region 130, a fourth waveguide region 140, and a fifth waveguide region 150 arranged in sequence along the optical signal propagation direction;

[0041] The first waveguide region 110 is a strip-shaped adiabatic tapered structure, and the waveguide width becomes wider along the transmission direction, ensuring single-mode transmission of optical signals in the waveguide and an increase in the optical mode field along the transmission direction;

[0042] The second waveguide region 120 is a strip-shaped waveguide with a uniform width, and its width is greater than the width of the end of the first waveguide region 110. The width of the second waveguide region 120 can excite multiple waveguide modes at its starting end, and can cause a stable spatial optical field strength distribution in the third waveguide region 130 due to multimode interference; preferably, the stable spatial optical field strength distribution is the position of the double image after waveguide multimode interference;

[0043] The third waveguide region 130 is a ridge waveguide, which includes a planar waveguide layer 135 and a ridge waveguide layer 134; the thickness of the ridge waveguide layer 134 is more than twice the thickness of the planar waveguide layer 135; the planar waveguide layer 135 is distributed throughout the third waveguide region 130, and its width is greater than the width of the second waveguide region 120; the length of the third waveguide region 130 is not greater than 3 um; the ridge waveguide layer 134 includes a doped waveguide 131, a transmission waveguide 132, and a doped waveguide 133 distributed in sequence along the vertical propagation direction; the width of the transmission waveguide 132 is the same as the width of the second waveguide region 120; the widths of the doped waveguide 131 and the doped waveguide 133 are not less than 0.8 um; the edge spacing between the doped waveguide 131, the transmission waveguide 132, and the doped waveguide 133 is not less than 1 um to ensure no energy exchange between waveguides; the width of the planar waveguide is greater than or equal to the spacing between the outer edges of the doped waveguide 131 and the doped waveguide 133.

[0044] The fourth waveguide region 140 is a strip-shaped waveguide, whose width is the same as the second waveguide width, and it extends to the self-imaging position 502 of the optical field in the waveguide.

[0045] The germanium absorption layer 200 is located above the center position of the weak optical field region 501 of the third waveguide region 130, its waveguide width is less than the width of the transmission waveguide 132 of the third waveguide region 130, and its length is less than or equal to the length of the third waveguide region 130.

[0046] In the third waveguide region 130, N(P) ion heavy doping 405(401), N(P) ion light doping 404(402), undoped 403, P(N) ion light doping 402(404), and P(N) ion heavy doping 401(405) are sequentially performed along the vertical waveguide transmission direction, where the heavy doping ion concentration is greater than the light doping ion concentration.

[0047] The germanium-silicon hybrid photodetector capable of on-chip high-density integration further includes a positive electrode 301 and a negative electrode 302, which are electrically connected to the silicon waveguides in the P ion heavy doping 401 region and the N ion heavy doping region 405 respectively, and convert the carriers generated by the germanium absorption layer 200 into current.

[0048] It should be noted that the first, second, fourth, and fifth waveguide regions 150 are preferably strip waveguides because the transmission loss is low at this time, but it does not mean that these waveguide regions can only be strip waveguides.

[0049] The working principle of this embodiment is as follows: The optical signal is input in single mode from the first waveguide region 110, excites multiple modes and undergoes multimode interference through the second waveguide region 120, forms a stable spatial optical field intensity distribution in the third waveguide region 130, and then enables the optical field to achieve self-imaging through the fourth waveguide region 140, and forms a single-mode optical signal with stable transmission through the fifth waveguide region 150. The germanium absorption layer 200 is located at the center position of the double image, that is, the weak optical field region 501, absorbs the optical signal in this region, generates photo-generated carriers, and converts the optical signal into an electrical signal through doped ions and the electrode 300, characterizing the optical signal power in the waveguide. The remaining unabsorbed optical signals continue to be stably transmitted after passing through the silicon waveguide.

[0050] This embodiment proposes a germanium-silicon hybrid photodetector that can be highly integrated on a chip. There is a weak optical signal region 501 in the silicon transmission waveguide 100, and the germanium absorption layer 200 is above this region, which will not have too much impact on the original optical signal transmission. Therefore, the transmission function of the device can be realized. At the same time, due to the absorption performance of germanium, the germanium absorption layer 200 absorbs the weak optical signal below it and converts it into carriers, and uses the current to characterize the optical signal energy below it. Since the optical signal is stably transmitted in this device, this current can characterize the total energy of the optical signal in the waveguide.

[0051] See Figure 5 、 Figure 7 It should be noted that Figure 5 is a cross-sectional view along the Figure 7 dashed line direction in

[0052] The second waveguide region 120 described is a strip waveguide; the second waveguide region 120 is composed of N isosceles trapezoids with a height not greater than 1 um; the bottom width of each isosceles trapezoid is greater than the width of the end of the first waveguide region 110; the overlapping bottom width of the Nth isosceles trapezoid and the (N + 1)th isosceles trapezoid is equal;

[0053] The width of each isosceles trapezoid in the second waveguide region 120 is determined by an optimization algorithm (such as particle swarm algorithm, genetic algorithm, etc.) to ensure the minimum transmission loss of the silicon transmission waveguide 100;

[0054] The structure of the second waveguide region 120 can excite multiple waveguides at its starting end, and can enable the third waveguide region 130 to have a stable spatial optical field intensity distribution due to multimode interference; preferably, the stable spatial optical field intensity distribution is the position of the double image after waveguide multimode interference;

[0055] The width of the transmission waveguide 132 in the third waveguide region 130 is the same as the width of the end of the second waveguide region 120 and the beginning of the fourth waveguide region 140;

[0056] The fourth waveguide region 140 is a strip waveguide;

[0057] The fourth waveguide region 140 described above is composed of N isosceles trapezoids with a height not greater than 1 um; the bottom width of each isosceles trapezoid is greater than the starting width of the fifth waveguide region 150; the overlapping bottom widths of the Nth isosceles trapezoid and the (N + 1)th isosceles trapezoid are equal;

[0058] The widths of the isosceles trapezoids in the fourth waveguide region 140 are determined by an optimization algorithm (such as a particle swarm algorithm, a genetic algorithm, etc.) to enhance the self-imaging effect in the silicon waveguide and ensure the minimum transmission loss of the silicon transmission waveguide 100;

[0059] It should be noted that the first, second, fourth, and fifth waveguide regions 150 are preferably strip waveguides because the transmission loss is relatively low at this time, but it does not mean that these waveguide regions can only be strip waveguides;

[0060] It should be noted that the second and fourth waveguide regions 140 do not necessarily have to be composed of isosceles trapezoids, and can also be waveguides of other shapes, even irregular shapes, such as designing the structures of the second and fourth waveguide regions 140 using inverse design;

[0061] In this embodiment, an optimization algorithm is used to make the germanium absorption layer 200 have a smaller influence on the optical field and a stronger self-imaging effect, further reducing the waveguide transmission loss.

[0062] See Figure 7 、 Figure 8 It should be noted that Figure 8 is a cross-sectional view along the Figure 7 dotted line direction in

[0063] P ions 406 are doped in the third waveguide region 130; N ions 407 are doped at the top of the germanium absorption layer 200;

[0064] The germanium-silicon hybrid photodetector that can be highly integrated on a chip further includes a positive electrode 301 and a negative electrode 302, and the positive electrode 301 is electrically connected to the doped waveguide 131 and the doped waveguide 133 in the third waveguide region 130 respectively.

[0065] Refer to Figure 9 、 Figure 10 、 Figure 11 It should be noted that Figure 10 is a cross-sectional view along the Figure 9 dotted line direction in

[0066] The length of the second waveguide region 120 is less than 0.2 um;

[0067] The described third waveguide region 130 does not necessarily form a stable spatial light field intensity distribution;

[0068] The described germanium absorption layer 200 includes a first germanium absorption layer 201 and a second germanium absorption layer 202, which are respectively located above both sides of the transmission waveguide 132 in the third waveguide region 130;

[0069] In the third waveguide region 130, both the doped waveguide 131 and the doped waveguide 133 are doped with P ions, and both the first germanium absorption layer 201 and the second germanium absorption layer 202 are doped with N ions;

[0070] The described germanium-silicon hybrid photodetector capable of on-chip high-density integration further includes two positive electrodes 301 and two negative electrodes 302. The two positive electrodes 301 are electrically connected to the doped waveguide 131 and the doped waveguide 133 respectively, and the two negative electrodes 302 are electrically connected to the first germanium absorption layer 201 and the second germanium absorption layer 202 respectively.

[0071] In this embodiment, since the starting width of the second wave region suddenly increases compared with the first waveguide region 110, there are weak light field regions 501 on both sides at the start of the third waveguide region 130. The germanium absorption layer 200 only absorbs the energy in this region and does not affect the original optical signal transmission in the waveguide.

[0072] The above is only the preferred embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can make appropriate changes or variations within the technical scope disclosed by the present invention, and such changes or variations should be covered within the protection scope of the present invention.

Claims

1. A germanium-silicon hybrid photodetector device capable of high-density integration, characterized in that: It includes a silicon transmission waveguide and a germanium absorption layer located thereon; wherein, the silicon transmission waveguide includes a first waveguide region, a second waveguide region, a third waveguide region, a fourth waveguide region, and a fifth waveguide region arranged in sequence along the optical signal propagation direction; the waveguide width in the first waveguide region becomes wider or remains unchanged along the propagation direction; the waveguide width at each location in the second waveguide region is greater than or equal to that of the first waveguide region and the fifth waveguide region, where multiple modes are excited and multimode interference occurs; the third waveguide region is a ridge waveguide, and its waveguide width is greater than that of the other four waveguide regions; the third waveguide region includes a planar waveguide layer and a ridge waveguide layer in the vertical direction, where the height of the ridge waveguide layer is greater than that of the planar waveguide layer; the ridge waveguide layer of the third waveguide region includes two or more ridge waveguide regions arranged at intervals, and the edge interval of each ridge waveguide region is greater than or equal to 1um to ensure that no energy exchange occurs between the ridge waveguides; when the optical signal is transmitted, there is a stable spatial light field intensity distribution in the third waveguide region; the waveguide width at each location in the fourth waveguide region is greater than or equal to that of the first waveguide region and the fifth waveguide region; the waveguide width in the fifth waveguide region becomes narrower or remains unchanged along the propagation direction; the germanium absorption layer is located above the weak distribution region of the light field in the third waveguide region; the length of the germanium absorption layer is less than or equal to the length of the third waveguide region.

2. The germanium-silicon hybrid photodetector device according to claim 1, wherein: in the first waveguide region and the fifth waveguide region, the optical signal is transmitted in the fundamental mode; the structures of the second waveguide region and the fourth waveguide region both support multiple optical wave modes.

3. The germanium-silicon hybrid photodetector according to claim 1 or 2, characterized in that: The widths of the second waveguide region and the fourth waveguide region may be the same everywhere or not necessarily the same everywhere.

4. The germanium-silicon hybrid photodetector according to claim 1 or 2, characterized in that: The structures of the second waveguide region and the fourth waveguide region can be designed using an optimization algorithm to reduce the reflection caused by the germanium absorption layer above the third waveguide region and to make there be a stable spatial light field intensity distribution in the third waveguide region.

5. The germanium-silicon hybrid photodetector according to claim 1 or 2, characterized in that, It further includes: ion doping and an electrode structure; the ion doping and the electrode structure include a horizontal mode and a vertical mode according to the distribution of the germanium absorption region; the electrode structure includes a positive electrode and a negative electrode.

6. The germanium-silicon hybrid photodetector device according to claim 5, wherein: for the germanium-silicon hybrid photodetector device doped according to the vertical mode, the third waveguide region is sequentially subjected to P or N ion heavy doping, P or N ion light doping, no doping, N or P ion light doping, and N or P ion heavy doping along the vertical optical signal propagation direction; the ion concentration in the heavy doping region is greater than that in the light doping region.

7. The germanium-silicon hybrid photodetector device according to claim 5, wherein: for the germanium-silicon hybrid photodetector device doped according to the vertical mode, there is one or more germanium absorption regions above the third waveguide region, and the electrical signal representing the optical transmission power is the sum of the electrical signals generated by any germanium absorption region absorbing the optical signal.

8. The germanium-silicon hybrid photodetector device according to claim 5, wherein: for the germanium-silicon hybrid photodetector device doped according to the vertical mode, the third waveguide region is doped with P ions, and the top of the germanium absorption layer is doped with N ions.

9. The germanium-silicon hybrid photodetector device according to claim 5, wherein: According to the germanium-silicon hybrid photodetector doped in the vertical manner, the positive electrode is electrically connected to the P-ion heavily doped region, and the negative electrode is electrically connected to the N-ion heavily doped region.

10. The germanium-silicon hybrid photodetector according to claim 5, wherein: According to the germanium-silicon hybrid photodetector doped in the vertical manner, the positive electrode is electrically connected to the top of the germanium absorption layer, and the negative electrode is electrically connected to both ends of the third waveguide region.

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