CN111192891B - Silicon photodetector, distance measuring method and device - Google Patents
Silicon photodetector, distance measuring method and device Download PDFInfo
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 142
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 100
- 239000010703 silicon Substances 0.000 title claims abstract description 100
- 238000000034 method Methods 0.000 title claims abstract description 27
- 238000010521 absorption reaction Methods 0.000 claims abstract description 173
- 230000003287 optical effect Effects 0.000 claims abstract description 106
- 239000000463 material Substances 0.000 claims abstract description 17
- 238000002198 surface plasmon resonance spectroscopy Methods 0.000 claims abstract description 7
- 238000002310 reflectometry Methods 0.000 claims description 11
- 238000004364 calculation method Methods 0.000 claims description 5
- 230000007274 generation of a signal involved in cell-cell signaling Effects 0.000 claims description 5
- 230000031700 light absorption Effects 0.000 abstract description 15
- 238000006243 chemical reaction Methods 0.000 abstract description 13
- 230000008033 biological extinction Effects 0.000 abstract description 8
- 238000010586 diagram Methods 0.000 description 43
- 230000008859 change Effects 0.000 description 29
- 238000002835 absorbance Methods 0.000 description 20
- 230000000694 effects Effects 0.000 description 12
- 238000002834 transmittance Methods 0.000 description 12
- 230000008569 process Effects 0.000 description 7
- 238000004088 simulation Methods 0.000 description 7
- 230000010355 oscillation Effects 0.000 description 5
- 238000002598 diffusion tensor imaging Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000002210 silicon-based material Substances 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 238000001579 optical reflectometry Methods 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 238000013459 approach Methods 0.000 description 1
- 238000003491 array Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910021418 black silicon Inorganic materials 0.000 description 1
- 239000013590 bulk material Substances 0.000 description 1
- 230000000295 complement effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 150000003376 silicon Chemical class 0.000 description 1
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14601—Structural or functional details thereof
- H01L27/14625—Optical elements or arrangements associated with the device
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/06—Systems determining position data of a target
- G01S17/08—Systems determining position data of a target for measuring distance only
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/481—Constructional features, e.g. arrangements of optical elements
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/02—Details
- H01L31/0232—Optical elements or arrangements associated with the device
- H01L31/02327—Optical elements or arrangements associated with the device the optical elements being integrated or being directly associated to the device, e.g. back reflectors
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Abstract
The application provides a silicon photodetector, a ranging method and a ranging device, and relates to the technical field of image sensors. The silicon photodetector includes: a detector and a light enhancement absorption array; the detector is used for receiving the optical signal and generating an electric signal; the optical enhancement absorption array is arranged on the surface of the detector and used for increasing the absorption of the detector to the optical signal, wherein the geometric structure of the optical enhancement absorption array is obtained based on the wave band information of the optical signal and the optical property of the material of the detector in the optical signal, and the optical property at least comprises the refractive index or the absorption rate of the detector. By arranging the light enhancement absorption array on the surface of the detector of the silicon photodetector, the surface plasmon resonance phenomenon can be generated on the surface of the detector of the silicon photodetector, so that the overall extinction ratio of the silicon photodetector is increased, the light absorption of the silicon photodetector in a near-infrared band is enhanced, the photoelectric conversion efficiency of the silicon photodetector in the near-infrared band is enhanced, and the quantum efficiency is effectively improved.
Description
Technical Field
The invention relates to the technical field of image sensors, in particular to a silicon photodetector, a ranging method and a ranging device.
Background
Silicon-based materials have recently been widely used in the field of image sensors due to their compatibility with CMOS (Complementary Metal Oxide Semiconductor ) fabrication processes and low cost properties. Typically, silicon-based materials are indirect bandgap semiconductor materials, and due to the limitation of their band gap of-1.2 eV, the quantum efficiency of silicon-based image sensors (CMOS Image Sensor) in the near-infrared band is greatly reduced. For a TOF (time of Flight) device based on silicon, since an active light source of the TOF device is generally in a near infrared band, quantum efficiency in the band is too low, so that the TOF chip has a larger range error, and it is important how to improve the quantum efficiency of the silicon material.
In the prior art, the quantum efficiency can be improved by increasing the light absorption by increasing the thickness of the epitaxial layer, but this approach can lead to increased crosstalk between the pixels of the sensor chip. Although DTI (diffusion tensor imaging) can alleviate crosstalk to some extent, the process of deep DTI increases the process difficulty in the whole pixel preparation process. In addition, reflection can be reduced and absorption can be increased by introducing a black silicon process with a pyramid structure on the silicon surface, but the process also causes serious optical crosstalk in the pixel of the image sensor chip, and a deep DTI technology is still needed to reduce isolation crosstalk.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides a silicon photodetector, a ranging method and a ranging device, so as to solve the problems of low light absorption efficiency and low quantum rate of the silicon photodetector, which result in low accuracy of a ranging result in the prior art.
In order to achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:
in a first aspect, embodiments of the present application provide a silicon photodetector, including: a detector and a light enhancement absorption array;
the detector is used for receiving the optical signal and generating an electric signal;
the optical enhancement absorption array is arranged on the surface of the detector and is used for increasing the absorption of the detector to the optical signal, wherein the geometric structure of the optical enhancement absorption array is obtained based on the wave band information of the optical signal and the optical property of the material of the detector in the optical signal, and the optical property at least comprises the refractive index or the absorption rate of the detector.
Optionally, the light enhanced absorption array comprises at least one protruding entity, or at least one hollow cavity; the geometry of the protruding entity comprises a symmetrical structure or an asymmetrical structure, and the geometry of the hollow cavity comprises a symmetrical structure or an asymmetrical structure.
Optionally, the geometry of the light enhanced absorption array comprises at least an array of silicon rings, or an array of silicon cylinders.
Optionally, the light enhanced absorption array is the silicon ring array; the inner diameter, outer diameter and thickness of each silicon ring are obtained from the absorptivity of the detector to the optical signal.
Optionally, the light enhancement absorption array is the silicon cylindrical array; the radius and thickness of each silicon cylinder are obtained from the absorptivity of the detector to the optical signal.
Optionally, the absorptivity of the detector to the optical signal is calculated according to the structure of the light enhancement absorption array, the reflectivity and the refractive index of the detector and the light enhancement absorption array.
Optionally, each silicon ring in the silicon ring array has a thickness of 20nm, an outer diameter of 280nm, and an inner diameter of 170nm, and the spacing between the silicon rings is 1500nm for the optical signal of 940 nm.
Optionally, the silicon cylinder has a thickness of 20nm and a radius of 180nm, and the silicon rings have a spacing of 1400nm for the optical signal of 940 nm.
In a second aspect, an embodiment of the present application further provides a ranging method, which is applied to the silicon photodetector in the first aspect, where the method includes:
generating an electrical signal according to the optical signal received by the silicon photodetector;
acquiring signal parameters output by the detector according to the electric signals;
and calculating the distance between the detector and the target object according to the signal parameters.
In a third aspect, an embodiment of the present application further provides a ranging apparatus, which is applied to the ranging method in the second aspect, where the apparatus includes: the device comprises a signal generation module, an acquisition module and a calculation module;
the signal generation module is used for generating an electric signal according to the optical signal received by the silicon optical detector;
the acquisition module is used for acquiring signal parameters output by the detector according to the electric signals;
and the calculating module is used for calculating the distance between the detector and the target object according to the signal parameters.
The beneficial effects of this application are:
the embodiment of the application provides a silicon photodetector, a ranging method and a device, wherein the silicon photodetector comprises a detector and a light enhancement absorption array; the detector is used for receiving the optical signal and generating an electric signal; the optical enhancement absorption array is arranged on the surface of the detector and used for increasing the absorption of the detector to the optical signal, wherein the geometric structure of the optical enhancement absorption array is obtained based on the wave band information of the optical signal and the optical property of the material of the detector in the optical signal, and the optical property at least comprises the refractive index or the absorption rate of the detector. By arranging the light enhancement absorption array on the detector surface of the silicon photodetector, the surface plasmon resonance phenomenon can be generated on the detector surface of the silicon photodetector, so that the overall extinction ratio of the silicon photodetector is increased, the light absorption of the silicon photodetector in a near-infrared band is enhanced, the photoelectric conversion efficiency of the silicon photodetector in the near-infrared band (especially for the near-infrared band with the wavelength of about 900 nm) is enhanced, and the quantum efficiency is effectively improved.
The geometry of the light enhanced absorption array may comprise an array of silicon rings, or an array of silicon cylinders, among others. When the geometry of the light enhancement absorption array is a silicon ring array, the thickness of each silicon ring in the silicon ring array is 20nm, the outer diameter is 280nm, the inner diameter is 170nm, for 940nm optical signals, the distance between the silicon rings is 1500nm, and the light absorption effect of the silicon photodetector is good, so that the photoelectric conversion efficiency is high, and the quantum rate is high. When the geometry of the light enhancement absorption array is a silicon cylindrical array, the thickness of the silicon cylinder is 20nm, the radius is 180nm, and when the interval between silicon rings is 1400nm for 940nm of optical signals, the light absorption effect of the silicon photodetector is better, so that the photoelectric conversion efficiency is higher, and the quantum rate is higher.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic top view of a silicon photodetector according to an embodiment of the present disclosure;
FIG. 2 is a schematic side view of a silicon photodetector according to an embodiment of the present disclosure;
FIG. 3 is a schematic diagram of a light enhancement absorption array according to an embodiment of the present disclosure;
FIG. 4 is a schematic waveform diagram showing the effect on the optical properties of a detector with/without an enhanced absorption array according to an embodiment of the present application;
FIG. 5 is a schematic diagram of a variation waveform of different optical properties of a detector with/without an enhanced absorption array according to an embodiment of the present application;
FIG. 6 is a schematic diagram of a geometric dimension change of a light-enhanced absorption array and a change waveform of optical properties of a detector according to an embodiment of the present application;
FIG. 7 is a schematic diagram showing the variation of the geometrical pitch and the optical properties of the detector in the light-enhanced absorption array with a specific dimension according to the embodiment of the present application;
FIG. 8 is a schematic diagram of another light enhancement absorption array according to an embodiment of the present disclosure;
FIG. 9 is a schematic waveform diagram of the effect on the optical properties of a detector with another enhanced absorption array with/without light provided by embodiments of the present application;
FIG. 10 is a schematic diagram of a variation waveform of different optical properties of another detector provided in an embodiment of the present application with/without an enhanced absorption array;
FIG. 11 is a schematic diagram of a geometric dimension change of a light enhancement absorption array and a change waveform of optical properties of a detector according to another embodiment of the present application;
FIG. 12 is a schematic diagram showing the variation of the geometrical pitch and the optical properties of the detector in the light-enhanced absorption array at another specific dimension according to the embodiment of the present application;
fig. 13 is a flow chart of a ranging method according to an embodiment of the present application;
fig. 14 is a schematic structural diagram of a ranging device according to an embodiment of the present application.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Fig. 1 is a schematic top view of a silicon photodetector according to an embodiment of the present disclosure; fig. 2 is a schematic side view structure of a silicon photodetector according to an embodiment of the present application. Please understand with reference to fig. 1 and 2. The silicon photodetector includes: a detector and a light enhancement absorption array; the detector 110 is configured to receive the optical signal and generate an electrical signal; the optical enhancement absorption array is arranged on the surface of the detector and used for increasing the absorption of the detector to the optical signal, wherein the geometric structure of the optical enhancement absorption array is obtained based on the wave band information of the optical signal and the optical property of the material of the detector in the optical signal, and the optical property at least comprises the refractive index or the absorption rate of the detector.
First, the principle of the light enhancement absorption array to increase the absorption of the light signal by the detector needs to be described in order to better understand the technical point of the present invention.
Optionally, the surface plasmon phenomenon is described first, where the surface plasmon is a collective oscillation formed by interaction of free charges on the surface of the material with an external electric field and an optical field, and propagates along the surface of the material. For a bulk material (approximately greater than 10 wavelengths in size), the frequency of oscillation is shown in equation 1:
wherein omega sp Is the frequency of surface plasmons, ω p The material has a plasma oscillation frequency epsilon m And epsilon d The complex dielectric constants of the material and the surrounding medium, respectively.
For a structure in which the surface of the material propagates approximately (about 0.1-10 times the wavelength of the incident light), the oscillation of the surface plasmon is limited to the object surface to oscillate reciprocally. The oscillation frequency of which is related to the size, geometry, material, wavelength of incident light, etc. The stronger the localized surface plasmon resonance, the stronger the near field enhancement, and the more energy is localized in the near field and transferred to nearby materials or dissipated as heat, resulting in an increase in extinction cross section. For spheres, their extinction cross-section sigma ext Can be expressed as the following equation 2:
wherein c is the speed of light, V is the volume of the sphere, ε d For the dielectric constant of the surrounding medium, ε' m (omega) and ε' m (omega) represents the real and imaginary parts of the dielectric constant of the sphere material, respectively, epsilon m (ω)＝ε' m (ω)+iε” m (omega). So when ε' m (ω)+2ε d At =0, the extinction cross-section is maximum, meaning that the most energy is localized at the structured surface rather than reflected or transmitted.
That is, in the scheme of the application, the surface plasmon resonance phenomenon can be generated on the detector surface of the silicon photodetector by arranging the light enhancement absorption array on the detector surface of the silicon photodetector, so that the overall extinction ratio of the silicon photodetector is increased, the light absorption of the silicon photodetector in a near infrared band is enhanced, the photoelectric conversion efficiency of the silicon photodetector in the near infrared band is enhanced, and the quantum efficiency is effectively improved.
As shown in fig. 1, the light enhancement absorption array may comprise different structures, alternatively the structure of the light enhancement absorption array may be determined based on the band information of the light signal received by the silicon photodetector and the optical properties of the material of the detector under the light signal. The determination of the geometry of the light enhanced absorption array can be understood by the following specific examples.
Alternatively, fig. 1 illustrates only one shape of each structure in the light-enhanced absorption array, that is, a circle, and in actual arrangement, the shape of each structure in the light-enhanced absorption array may be not limited to a circle, but may be various polygons such as a circle, a square, a pentagon, a hexagon, and the like.
In summary, the silicon photodetector provided in this embodiment includes a detector and a light enhancement absorption array; the detector is used for receiving the optical signal and generating an electric signal; the optical enhancement absorption array is arranged on the surface of the detector and used for increasing the absorption of the detector to the optical signal, wherein the geometric structure of the optical enhancement absorption array is obtained based on the wave band information of the optical signal and the optical property of the material of the detector in the optical signal, and the optical property at least comprises the refractive index or the absorption rate of the detector. The surface plasmon resonance phenomenon can be generated on the detector surface of the silicon photodetector by arranging the light enhancement absorption array on the detector surface of the silicon photodetector, so that the overall extinction ratio of the silicon photodetector is increased, the light absorption of the silicon photodetector in a near infrared band is enhanced, the photoelectric conversion efficiency of the silicon photodetector in the near infrared band is enhanced, the quantum efficiency is effectively improved, and the array is arranged in the sensor, so that the high efficiency and the accuracy of the sensor work are ensured.
Optionally, the light enhanced absorption array comprises at least one protruding entity, or at least one hollow cavity; the geometry of the protruding entities comprises a symmetrical structure or an asymmetrical structure, and the geometry of the hollow cavity comprises a symmetrical structure or an asymmetrical structure.
Optionally, when the protruding entity or the hollow cavity is non-circular or non-regular polygon, the geometry of the protruding entity or the hollow cavity is an asymmetric structure, and when the protruding entity or the hollow cavity is circular or regular polygon, the geometry of the protruding entity or the hollow cavity is a symmetric structure. In particular, the absorption of the detector to the optical signal can be enhanced whether the geometry of the protruding entity or hollow cavity is a symmetrical or asymmetrical structure.
Optionally, the geometry of the light enhanced absorption array comprises at least an array of silicon rings, or alternatively, an array of silicon cylinders.
In the embodiment of the present application, the geometry of the light enhancement absorption array is exemplified by a silicon ring array, or a silicon cylinder array.
Fig. 3 is a schematic structural diagram of a light enhancement absorption array according to an embodiment of the present application. Alternatively, as shown in fig. 3, the light-enhanced absorption array is a silicon ring array; the inner diameter, the outer diameter and the thickness of each silicon ring are obtained according to the absorptivity of the detector to the optical signal, the basis of size design is provided through the optimization of absorptivity simulation or experimental values, the highest efficiency of the whole array for light quantum conversion after light absorption in the use process is ensured, the refractive index or the transmissivity of the detector can indirectly reflect the absorptivity of the detector, for example, at least one value of the transmissivity or the refractive index is reduced by an array enhancement method, and further, the larger absorptivity is obtained.
FIG. 4 is a schematic waveform showing the effect on the optical properties of a detector with/without enhanced absorption array according to an embodiment of the present application. Fig. 5 is a schematic diagram of a variation waveform of different optical properties of a detector in the presence/absence of an enhanced absorption array according to an embodiment of the present application.
Wherein, finite element software (COMSOL Multiphysics) can be used to perform simulation on performance parameters and the like of the detector provided with the light enhancement absorption array to obtain the waveform schematic diagram, wherein, the optical properties of the detector can include: reflectivity, transmissivity, absorptivity, and absolute absorptivity. The absolute absorptance is an absorptance in the case where reflection is not considered. Optionally, the absorbance of the optical signal by the detector is calculated according to the structure of the light enhancement absorption array, the reflectivity of the detector and the light enhancement absorption array, and the refractive index.
Specifically, fig. 4 (1) is a schematic diagram of waveforms of reflectivity, transmissivity, absorptivity and absolute absorptivity of the detector in the case of a non-enhanced absorption array; fig. 4 (2) is a schematic diagram of reflectance, transmittance, absorbance and absolute absorbance waveforms of a detector with a light enhanced absorption array. In fig. 4 (1) and 4 (2), curve 1 represents transmittance, curve 2 represents reflectance, curve 3 represents absorptance, and curve 4 represents absolute transmittance.
As can be seen from fig. 4, in the presence of the light enhanced absorption array, the reflectivity and transmissivity of the detector is reduced relative to that in the absence of the light enhanced absorption array; whereas the absorbance and absolute absorbance of the detector are raised relative to the absorbance array without enhancement. That is, after the light enhancement absorption array is arranged on the surface of the detector of the silicon photodetector, the detector absorbs light signals more strongly, so that the photoelectric conversion efficiency can be effectively improved, and the quantum efficiency is further improved.
Specifically, fig. 5 (1) is a schematic diagram showing a variation waveform of transmittance in the case of the absorption array with/without enhancement; FIG. 5 (2) is a schematic diagram showing the variation waveform of the reflectance in the case of the absorption array with/without enhancement; FIG. 5 (3) is a schematic diagram showing the variation waveform of the absorption rate in the case of the absorption array with/without enhancement; fig. 5 (4) is a schematic diagram showing the variation waveform of the absolute absorption rate in the case of the absorption array with/without enhancement. In fig. 5 (1), 5 (2), 5 (3), and 5 (4), curve 1 represents a non-light-enhanced absorption array, and curve 2 represents a light-enhanced absorption array.
Wherein at a wavelength of 940nm, the changes in reflectance, transmittance, absorptance, and absolute absorptance are shown in the following table 1:
it can be further stated that in the presence of the light-enhanced absorption array, the reflectivity and transmissivity of the detector are reduced and the absorptivity and absolute absorptivity are improved.
Fig. 6 is a schematic diagram of geometric dimension change of a light-enhanced absorption array and optical property change waveforms of a detector according to an embodiment of the present application. FIG. 6 (1) is a schematic diagram showing geometric dimension change and transmittance change waveforms of the light-enhanced absorption array; FIG. 6 (2) is a schematic diagram showing geometric dimension change and reflectivity change waveforms of the light enhancement absorption array; FIG. 6 (3) is a schematic diagram showing geometric dimension change and absolute absorptivity change waveforms of the light enhancement absorption array; fig. 6 (4) is a schematic diagram of geometric dimension change and absorptivity change waveforms of the light enhancement absorption array. Wherein, the geometrical structural dimension change of the light enhancement absorption array is correspondingly generated for the optical signal with the wavelength of 940 nm.
Through numerical simulation and theoretical calculation, it can be seen that when the parameters of the inner diameter and the outer diameter of each silicon ring in the light enhancement absorption array are changed, the light reflectivity, the transmissivity and the absorptivity of the light enhancement absorption array are different at the wavelength of 940nm, and the light enhancement absorption array is in an up-and-down fluctuation state. Wherein the absorbance (0.755) and the absolute absorbance (0.523) reach maximum values when the outer diameter radius is 280 nm.
Optionally, in some embodiments, the spacing between each geometry in the light enhancement absorption array also affects the light absorption of the detector to some extent. Taking the light enhancement absorption array as a silicon ring array as an example, when the space between each silicon ring in the light enhancement absorption array is changed, the absorption rate and absolute absorption rate of the detector for infrared light can be changed, and different silicon ring spaces correspond to different resonance wavelengths. Through numerical simulation and theoretical calculation, the absorption intensity of the infrared light with the wavelength of 940nm corresponding to the change of the interval between the silicon rings is calculated.
Fig. 7 is a schematic diagram of a variation waveform of the geometrical pitch and the optical property of the detector in the light-enhanced absorption array with a specific size according to an embodiment of the present application. Wherein, the thickness of the silicon ring in the light enhancement absorption array is 20nm, the outer diameter is 280nm, the inner diameter is 170nm, that is, fig. 7 is a schematic diagram of the change waveform of the absorption rate and the absolute absorption rate of the light enhancement absorption array to 940nm wavelength infrared light when the thickness of the silicon ring in the light enhancement absorption array is 20nm, the outer diameter is 280nm, and the inner diameter is 170 nm. Wherein curve 1 represents the absorption rate and curve 2 represents the absolute absorption rate.
The spacing between silicon rings in the light enhancement absorption array is in the range of 600-1520nm when reflection from the detector surface is considered, and the absorbance of the detector for 940nm wavelength infrared light is maximum at a spacing of 1500nm, at 62.46%, and the absolute absorbance of the detector for 940nm wavelength infrared light is approximately 84.49% when reflection from the detector surface is not considered.
In summary, in order to enhance the absorption of near infrared light by the silicon photodetector, the interval between the light enhancement absorption arrays needs to be calculated, and the different wavelengths have the corresponding size intervals, and the absorption of the required infrared light is reduced when the interval is larger than or smaller than the corresponding size interval. The computer logic may also be preset in the machine, particularly during design and fabrication, to achieve computer-aided manufacturing.
As is clear from the analysis of the results of the simulation experiments, in the present embodiment, the thickness of each silicon ring in the silicon ring array is 20nm, the outer diameter is 280nm, the inner diameter is 170nm, and the light absorption effect of the silicon photodetector is better when the interval between the silicon rings is 1500nm for 940nm optical signals, so that the photoelectric conversion efficiency is higher and the quantum rate is higher.
Optionally, the light enhancement absorption array is a silicon cylindrical array; the radius and thickness of each silicon cylinder are obtained from the absorptivity of the detector to the optical signal.
Fig. 8 is a schematic structural diagram of another light enhancement absorption array according to an embodiment of the present application. Alternatively, as shown in fig. 8, the light-enhanced absorption array is a silicon cylindrical array; wherein the radius and thickness of each silicon cylinder are obtained from the absorptivity of the detector to the optical signal.
FIG. 9 is a schematic waveform showing the effect on the optical properties of a detector with another enhanced absorption array with/without light provided by embodiments of the present application. FIG. 10 is a schematic diagram of a variation waveform of different optical properties of another detector provided in an embodiment of the present application in the presence/absence of an enhanced absorption array.
In particular, the process is similar to that of the study when the light-enhanced absorption array is a silicon ring array. FIG. 9 (1) is a schematic diagram of reflectance, transmittance, absorbance and absolute absorbance waveforms of a detector without an enhanced absorption array; fig. 9 (2) is a schematic diagram of reflectance, transmittance, absorbance and absolute absorbance waveforms of a detector with a light enhanced absorption array. In fig. 9 (1) and 9 (2), curve 1 represents transmittance, curve 2 represents reflectance, curve 3 represents absorptance, and curve 4 represents absolute absorptance.
As can be seen from fig. 9, in the presence of the light enhanced absorption array, the reflectivity and transmissivity of the detector is reduced relative to that in the absence of the light enhanced absorption array; whereas the absorbance and absolute absorbance of the detector are raised relative to the absorbance array without enhancement.
FIG. 10 (1) is a schematic diagram showing the variation waveform of transmittance in the case of an absorption array with/without enhancement; FIG. 10 (2) is a schematic diagram showing the variation waveform of the reflectance in the case of the absorption array with/without enhancement; FIG. 10 (3) is a schematic diagram showing the variation waveform of the absorption rate in the case of the absorption array with/without enhancement; fig. 10 (4) is a schematic diagram showing the variation waveform of the absolute absorption rate in the case of the absorption array with/without enhancement. In fig. 10 (1), 10 (2), 10 (3), and 10 (4), curve 1 indicates no light enhanced absorption array, and curve 2 indicates light enhanced absorption array.
Wherein, at a wavelength of 940nm, the changes of the reflectance, transmittance, absorptance, and absolute absorptance are shown in the following table 2:
it can also be stated that the reflectivity and transmissivity of the detector are reduced and the absorptivity and absolute absorptivity are increased in the presence of the light-enhanced absorption array.
FIG. 11 is a schematic diagram of a geometric dimension change of a light enhancement absorption array and a change waveform of optical properties of a detector according to another embodiment of the present application. FIG. 11 (1) is a schematic diagram showing geometric dimension change and transmittance change waveforms of the light-enhanced absorption array; FIG. 11 (2) is a schematic diagram showing geometric dimension change and reflectivity change waveforms of the light enhancement absorption array; FIG. 11 (3) is a schematic diagram showing geometric dimension change and absolute absorptivity change waveforms of the light enhancement absorption array; fig. 11 (4) is a schematic diagram of geometric dimension change and absorptivity change waveforms of the light enhancement absorption array. Wherein, the geometrical structural dimension change of the light enhancement absorption array is correspondingly generated for the optical signal with the wavelength of 940 nm.
Through numerical simulation and theoretical calculation, it can be seen that when the internal and external diameter parameters of the light enhancement absorption array are changed, the light reflectivity, the transmissivity and the absorptivity of the light enhancement absorption array are different at the wavelength of 940nm, and the light enhancement absorption array is in an up-and-down fluctuation state. The absolute absorbance (0.723) can be significantly enhanced when the outer diameter radius is 80nm, and the absorbance (relative absorbance) reaches the highest (0.812) when the outer diameter radius is 240 nm.
FIG. 12 is a schematic diagram showing the variation of the geometrical pitch and the optical properties of the detector in the light-enhanced absorption array at another specific dimension according to the embodiment of the present application. Wherein, the thickness of the silicon cylinder in the light enhancement absorption array is 20nm, the radius is 180nm, that is, fig. 12 is a schematic diagram of the change waveform of the absorption rate and the absolute absorption rate of the light enhancement absorption array to 940nm wavelength infrared light when the thickness of the silicon cylinder in the light enhancement absorption array is 20nm and the radius is 180 nm. Wherein curve 1 represents the absorption rate and curve 2 represents the absolute absorption rate.
When the reflection generated by the surface of the detector is considered, the absorption rate of the detector for 940nm infrared light reaches the maximum value of 79.45% when the interval between the silicon cylinders in the light enhancement absorption array is 1220 nm; when the silicon cylinders in the light enhancement absorption array are of the same size, the absolute absorption rate of the detector for 940nm infrared light reaches the maximum value of 94.76% when the interval between the silicon cylinders in the light enhancement absorption array is 1400nm without considering the reflection generated by the surface of the detector.
As shown by the analysis of the simulation experiment result performed on the silicon cylindrical array as the light enhancement absorption array, in the embodiment, the thickness of the silicon cylindrical is 20nm, the radius is 180nm, and for 940nm optical signals, when the interval between silicon rings is 1400nm, the light absorption effect of the silicon photodetector is better, so that the photoelectric conversion efficiency is higher and the quantum rate is higher.
In summary, the silicon photodetector provided in the embodiments of the present application includes a detector and a light enhancement absorption array; the detector is used for receiving the optical signal and generating an electric signal; the optical enhancement absorption array is arranged on the surface of the detector and used for increasing the absorption of the detector to the optical signal, wherein the geometric structure of the optical enhancement absorption array is obtained based on the wave band information of the optical signal and the optical property of the material of the detector in the optical signal, and the optical property at least comprises the refractive index or the absorption rate of the detector. By arranging the light enhancement absorption array on the surface of the detector of the silicon photodetector, the surface plasmon resonance phenomenon can be generated on the surface of the detector of the silicon photodetector, so that the overall extinction ratio of the silicon photodetector is increased, the light absorption of the silicon photodetector in a near-infrared band is enhanced, the photoelectric conversion efficiency of the silicon photodetector in the near-infrared band is enhanced, and the quantum efficiency is effectively improved.
The geometry of the light enhanced absorption array may comprise an array of silicon rings, or an array of silicon cylinders, among others. When the geometry of the light enhancement absorption array is a silicon ring array, the thickness of each silicon ring in the silicon ring array is 20nm, the outer diameter is 280nm, the inner diameter is 170nm, for 940nm optical signals, the distance between the silicon rings is 1500nm, and the light absorption effect of the silicon photodetector is good, so that the photoelectric conversion efficiency is high, and the quantum rate is high. When the geometry of the light enhancement absorption array is a silicon cylindrical array, the thickness of the silicon cylinder is 20nm, the radius is 180nm, and when the interval between silicon rings is 1400nm for 940nm of optical signals, the light absorption effect of the silicon photodetector is better, so that the photoelectric conversion efficiency is higher, and the quantum rate is higher.
Fig. 13 is a schematic flow chart of a ranging method according to an embodiment of the present application, and optionally, the ranging method is applied to the above-mentioned silicon photodetector, and the implementation subject of the method may be the silicon photodetector. As shown in fig. 13, the method may include:
s101, generating an electric signal according to an optical signal received by the silicon photodetector.
S102, acquiring signal parameters output by the detector according to the electric signals.
S103, calculating the distance between the detector and the target object according to the signal parameters.
Optionally, when the ranging method is performed by applying the silicon photodetector, the principle and technical effects are similar to those of the silicon photodetector, and are not described herein.
Fig. 14 is a schematic structural diagram of a ranging device according to an embodiment of the present application, where the device may include a signal generating module 201, an obtaining module 202, and a calculating module 203.
A signal generation module 201 for generating an electrical signal from the optical signal received by the silicon photodetector;
the acquisition module 202 is configured to acquire signal parameters output by the detector according to the electrical signal;
and the calculating module 203 is used for calculating the distance between the detector and the target object according to the signal parameters.
The above-mentioned device is used for executing the method provided in the foregoing embodiment, and its implementation principle and technical effects are similar, and will not be described herein again.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. A silicon photodetector, comprising: a detector and a light enhancement absorption array;
the detector is used for receiving the optical signal and generating an electric signal;
the optical enhancement absorption array is arranged on the surface of the detector and generates a surface plasmon resonance phenomenon for increasing the absorption of the detector to an optical signal, wherein the geometric structure of the optical enhancement absorption array is obtained based on the wave band information of the optical signal and the optical property of the material of the detector in the optical signal, and the optical property at least comprises the refractive index or the absorption rate of the detector; the geometry of the light enhancement absorption array is a circular ring, and the dimensions of the light enhancement absorption array include: the inner diameter, outer diameter and thickness of the ring, if the geometry is cylindrical, the dimensions of the light enhancement absorption array include: radius and thickness of the cylinder;
the absorptivity of the detector to the optical signals is calculated according to the geometric structure of the light enhancement absorption array, the reflectivity of the detector and the light enhancement absorption array and the refractive index.
2. The silicon photodetector of claim 1 wherein said light enhanced absorption array comprises at least one raised entity, or at least one hollow cavity; the geometry of the protruding entity comprises a symmetrical structure or an asymmetrical structure, and the geometry of the hollow cavity comprises a symmetrical structure or an asymmetrical structure.
3. The silicon photodetector of claim 1 wherein the geometry of the light enhanced absorption array comprises at least an array of silicon rings, or an array of silicon cylinders.
4. The silicon photodetector of claim 3 wherein said light enhanced absorption array is said silicon ring array; the inner diameter, outer diameter and thickness of each silicon ring are obtained from the absorptivity of the detector to the optical signal.
5. A silicon photodetector as defined in claim 3 wherein the light enhanced absorption array is the silicon cylindrical array; the radius and thickness of each silicon cylinder are obtained from the absorptivity of the detector to the optical signal.
6. The silicon photodetector of claim 4 wherein each silicon ring in said array of silicon rings has a thickness of 20nm, an outer diameter of 280nm and an inner diameter of 170nm, and wherein the spacing between the silicon rings is 1500nm for the optical signal at 940 nm.
7. The silicon photodetector of claim 5 wherein said silicon cylinder has a thickness of 20nm and a radius of 180nm, and wherein said silicon rings are spaced 1400nm apart for said optical signal at 940 nm.
8. A ranging method applied to the silicon photodetector of any one of claims 1 to 7, the method comprising:
generating an electrical signal according to the optical signal received by the silicon photodetector;
acquiring signal parameters output by the detector according to the electric signals;
and calculating the distance between the detector and the target object according to the signal parameters.
9. A ranging apparatus for use in the ranging method of claim 8, the apparatus comprising: the device comprises a signal generation module, an acquisition module and a calculation module;
the signal generation module is used for generating an electric signal according to the optical signal received by the silicon photodetector;
the acquisition module is used for acquiring signal parameters output by the detector according to the electric signals;
and the calculating module is used for calculating the distance between the detector and the target object according to the signal parameters.
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