Heterojunction wavelength sensor and sensing method

Abstract

The invention provides a heterojunction wavelength sensor and a sensing method, the heterojunction wavelength sensor comprises a first photoelectric detector, a second photoelectric detector, a first electron transport layer, a second electron transport layer and a second crystalline silicon film, the first photoelectric detector is characterized in that a first hole area is arranged on a first front electrode, and a first heterojunction is formed between the first electron transport layer and the first crystalline silicon film; the second photoelectric detector and the first photoelectric detector are arranged in a spaced mode in the second direction, the second front electrode is provided with a second hole opening area, a second heterojunction is formed between the second electron transmission layer and the second crystalline silicon thin film, and a third heterojunction is formed between the second crystalline silicon thin film and the hole transmission layer; the first photoelectric detector and the second photoelectric detector are arranged on one side of the reflecting surface of the reflecting mirror; and the isolation plate is arranged between the first photoelectric detector and the second photoelectric detector. Compared with a conventional sensing structure at the present stage, the sensor has the advantages of being simple in structure, low in production and processing cost, wide in application range, high in use flexibility, capable of effectively reducing reflection errors between devices and the like.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and in particular to a heterojunction wavelength sensor and a sensing method. Background Art

[0002] In the current field of optical sensing technology, wavelength sensors are key components, and their performance directly affects the effects of many application scenarios. Filter-free wavelength sensors have received extensive attention in recent years due to their unique advantages. However, the existing public technical solutions still have many problems to be solved in terms of comprehensive performance indicators, which seriously restricts their further development and application.

[0003] First, in the application of wavelength sensing in the visible and near-infrared bands indoors, most wavelength sensors without filter elements adopt a vertical stacking structure. Although this structure can detect wavelengths to a certain extent, it has obvious defects. When a single photodetector is working, its light response signal is easily interfered by the reflected light from the internal interface of the sensor. When light is incident on the inside of the sensor, reflection occurs at the interface of different photodetectors. These reflected lights will enter the photodetector again and superimpose on the effective light signal, resulting in a deviation in the signal received by the photodetector. In actual application scenarios, such as indoor environmental monitoring, biomedical testing, etc., this interference will greatly reduce the accuracy of wavelength recognition, thereby affecting the precise judgment of environmental parameters or the accurate analysis of biological samples.

[0004] Secondly, for common visible light and near-infrared light, existing wavelength sensing technology solutions have limitations. At present, most related research focuses only on the case of vertically incident light, while in actual application scenarios in the real world, it is more common for light to reach the sensor at an oblique incidence. In lighting systems, due to changes in the position and angle of the light source, light rarely shines vertically on the sensor. Existing wavelength sensing technology lacks effective response strategies in the case of oblique incidence, resulting in its inability to accurately measure wavelengths in actual use, making the universality and flexibility of wavelength testing seriously insufficient. This greatly limits the scope of application of wavelength sensors in many fields such as intelligent lighting control, ambient light monitoring, optical imaging, etc., and cannot meet diverse practical needs.

[0005] The wavelength sensors reported at this stage generally use PIN junction or PN junction photodetectors. During the manufacturing process of this type of detector, complex doping processes are required to accurately control the doping concentration and depth. Accurately controlling the doping concentration and depth requires highly precise equipment and complex process flows, which not only increases the difficulty and cost of device manufacturing, but also easily introduces errors. In actual work, this type of sensor determines the wavelength by calculating the ratio of the light response signals of two photodetectors. However, due to the influence of the internal structure of the detector and the manufacturing process, the resulting monotonic curve has a small value and is not smooth enough. This results in low accuracy in wavelength identification and low resolution, making it difficult to meet application scenarios with high requirements for wavelength measurement accuracy, such as wavelength multiplexing technology in optical communications and high-precision spectral analysis.

[0006] In summary, the existing wavelength sensors without filter elements have obvious deficiencies in comprehensive performance indicators such as sensing accuracy, test flexibility and sensing precision, and therefore an innovative technical solution is needed to solve these problems. Summary of the invention

[0007] To this end, the technical problem to be solved by the present invention is to overcome the obvious deficiencies in the comprehensive performance indicators of wavelength sensors in the prior art, such as sensing accuracy, test flexibility and sensing precision, and to provide a heterojunction wavelength sensor and a sensing method.

[0008] In order to solve the above technical problems, the present invention provides a heterojunction wavelength sensor, which includes: a first photodetector, which includes a first front electrode, a first electron transport layer, a first crystalline silicon film and a transparent electrode layer connected in sequence along a first direction, wherein a first opening area is provided on the first front electrode, a first heterojunction is formed between the first electron transport layer and the first crystalline silicon film, and the transparent electrode layer is connected to the side of the first crystalline silicon film facing the reflector; a second photodetector, the second photodetector is arranged at intervals with the first photodetector along the second direction, and includes a second front electrode, a second electron transport layer, a second crystalline silicon film, a hole transport layer and a back electrode layer connected in sequence along the first direction, wherein the first A second opening area is provided on the two front electrodes, a second heterojunction is formed between the second electron transport layer and the second crystalline silicon film, a third heterojunction is formed between the second crystalline silicon film and the hole transport layer, and the back electrode layer is connected to the side of the hole transport layer away from the reflector; a reflector, the first photodetector and the second photodetector are both arranged on one side of the reflecting surface of the reflector, the light wave to be measured is incident on the first photodetector from the first opening area at a preset angle, and a part of the light wave to be measured is transmitted by the first photodetector and then passes through the reflector to enter the second photodetector from the second opening area at the preset angle; an isolation plate, the isolation plate is arranged between the first photodetector and the second photodetector.

[0009] In one embodiment of the present invention, the preset angle is the angle between the incident direction of the light wave to be measured and the first direction, and the preset angle is 10° to 60°.

[0010] In one embodiment of the present invention, the first crystalline silicon film is a p-type doping structure, and its doping concentration range is 10 15 ~10 18 cm -3 , and its thickness is 1~6μm; the second crystalline silicon film is a p-type doping structure, and its doping concentration range is 10 15 ~10 18 cm -3 , with a thickness of 60-150 μm; the first electron transport layer and the second electron transport layer substrate are one of SnO2, TiO2, Ga2O3, ZnO or ITO, and the thickness is 30-300 nm in a planar two-dimensional structure, the first electron transport layer and the second electron transport layer are both n-type doped structures, and the doping concentration range is 10 15 ~10 18 cm -3 .

[0011] In one embodiment of the present invention, the first front electrode and the second front electrode are both planar hole structures, and the area of ​​the first opening area and the area of ​​the second opening area are both 100-4000000 μm 2 ; The first opening area and the second opening area are both configured as one of a circle, an ellipse, a triangle or a polygon.

[0012] In one embodiment of the present invention, the energy difference of the valence band edge at the first heterojunction interface is greater than the energy difference of the conduction band edge; the energy difference of the valence band edge at the second heterojunction interface is greater than the energy difference of the conduction band edge; the energy difference of the conduction band edge at the third heterojunction interface is greater than the energy difference of the valence band edge.

[0013] In one embodiment of the present invention, the hole transport layer is configured as a planar two-dimensional structure with a thickness of 40 to 400 nm, and its substrate is one of Spiro-OMeTAD, MoO3, NiO or WO3, which is a p-type doped structure, and the doping concentration range is 10 16 ~10 19 cm -3 .

[0014] In one embodiment of the present invention, the spacing distance between the reflector and the first photodetector and the second photodetector in the first direction is equal, and both are 500μm~10mm, and the reflecting surface area of ​​the reflector covers the projection area of ​​the first opening area and the second opening area in the first direction; the surface of the isolation plate is covered with a blackening treatment layer, which isolates the first photodetector and the second photodetector in the second direction.

[0015] The present invention also provides a heterojunction wavelength sensing method, which uses the above-mentioned heterojunction wavelength sensor to perform wavelength sensing of a light wave to be measured, and comprises: step S1, allowing the light wave to be measured to enter a first photodetector at a preset angle, part of the light wave to be measured is absorbed by the first crystalline silicon film, and forms a first photocurrent under the action of the built-in electric field of the first heterojunction, and the remaining part of the light wave to be measured is transmitted out of the first photodetector; step S2, reflecting the light wave to be measured that is transmitted out of the first photodetector into the second photodetector through a reflector; step S3, the light wave to be measured reflected into the second photodetector is absorbed by the second crystalline silicon film, and forms a second photocurrent under the action of the built-in electric fields of the second heterojunction and the third heterojunction; step S4, respectively detecting the first photocurrent response intensity and the second photocurrent response intensity; step S5, fitting a monotonic photocurrent ratio-wavelength curve within the wavelength range to be measured through the ratio of the first photocurrent response intensity and the second photocurrent response intensity, so as to complete wavelength sensing.

[0016] In one embodiment of the present invention, in steps S1 to S5, the first photodetector and the second photodetector are isolated by an isolation plate; in step S1, the light wave to be measured is incident on the first photodetector through the first opening area at a preset angle, and the first crystalline silicon film absorbs part of the light to be measured and transmits the rest of the light to be measured; in step S2, the transmitted light of the first photodetector is incident through the second opening area under the action of the reflector.

[0017] The above technical solution of the present invention has the following advantages compared with the prior art: The heterojunction wavelength sensor and sensing method described in the present invention mainly absorb short-wavelength light through the single heterojunction structure and relatively thin crystalline silicon in the first photodetector, and mainly absorb long-wavelength light through the double heterojunction structure and relatively thick crystalline silicon in the second photodetector, thereby effectively increasing the ratio of the output photocurrent, improving the smoothness of the ratio curve and the wavelength range that can be sensed. Compared with conventional silicon-based photoelectric devices using PIN and PN junctions, the present application can greatly reduce the complexity of the processing technology while performing high-precision sensing. In addition, the present application uses a reflector and a front electrode with an opening area to achieve the regulation of the optical path, which not only makes it suitable for sensing incident light waves at different angles, but also changes the traditional vertical stacking structure into a horizontal arrangement structure, thereby achieving the purpose of avoiding mutual interference between the two photodetectors. Based on this, compared with the conventional sensing structure at this stage, the present application has the advantages of simple structure, low production and processing cost, wide application range, strong flexibility of use, and can effectively reduce the reflection error between devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings.

[0019] Figure 1 is a schematic structural diagram of a heterojunction wavelength sensor in a preferred embodiment of the present invention; Figure 2 yes Figure 1 The working principle diagram of the heterojunction wavelength sensor under zero bias is shown; Figure 3 yes Figure 1 The first photodetector and the second photodetector in the heterojunction wavelength sensor are shown in FIG. 1 and FIG. 2 when the incident wavelength range is 200-1000 nm, the incident angle is 45°, and the incident light power density is 0.3 mW cm -2 Photocurrent density-wavelength curve; Figure 4 yes Figure 1The heterojunction wavelength sensor shown in the figure has an incident angle of 30° and an incident light power density of 0.3 mW cm -2 The photocurrent ratio-wavelength curve corresponding to TE and TM waves under illumination; Figure 5 yes Figure 1 The heterojunction wavelength sensor shown in the figure has an incident light power density of 0.3 mW cm -2 , the corresponding photocurrent ratio-wavelength curves under the conditions of incident angles of 15°, 30°, 45° and 60°; Figure 6 yes Figure 5 The representation of the data in the logarithmic coordinate system; Figure 7 It is adjustment Figure 1 After the first crystalline silicon film thickness in the heterojunction wavelength sensor is shown, when the incident wavelength is 200~1000nm, the polarization is TM wave, the incident angle is 45°, and the incident light power density is 0.3mWcm -2 The corresponding photocurrent ratio-wavelength curve below; Figure 8 It is adjustment Figure 1 After the second crystalline silicon film thickness in the heterojunction wavelength sensor is shown, when the incident wavelength is 200~1000nm, the polarization is TM wave, the incident angle is 45°, and the incident light power density is 0.3mWcm -2 The corresponding photocurrent ratio-wavelength curve below; Fig. 9 This is a photocurrent ratio-wavelength curve obtained by the stacked wavelength sensor in the comparative example when the light wave to be measured is incident vertically.

[0020] Explanation of the reference numerals in the specification: 100, first photodetector; 110, first front electrode; 111, first opening area; 120, first electron transport layer; 130, first crystalline silicon film; 140, transparent electrode layer; 200, second photodetector; 210, second front electrode; 211, second opening area; 220, second electron transport layer; 230, second crystalline silicon film; 240, hole transport layer; 250, back electrode layer; 300, reflector; 400, isolation plate; 500, light wave to be measured; X, first direction; Y, second direction. DETAILED DESCRIPTION

[0021] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention. Example

[0022] See also Figure 1As shown, this embodiment provides a heterojunction wavelength sensor, which includes: a first photodetector 100, which includes a first front electrode 110, a first electron transport layer 120, a first crystalline silicon film 130 and a transparent electrode layer 140 connected in sequence along a first direction X, wherein a first opening area 111 is provided on the first front electrode 110, a first heterojunction is formed between the first electron transport layer 120 and the first crystalline silicon film 130, and the transparent electrode layer 140 is connected to the side of the first crystalline silicon film 130 facing the reflector 300, which is used to transmit light and receive carriers at the same time; a second photodetector 200, wherein the second photodetector 200 is connected to the first crystalline silicon film 130. The first photodetector 100 is arranged at intervals along the second direction Y, and includes a second front electrode 210, a second electron transport layer 220, a second crystalline silicon film 230, a hole transport layer 240 and a back electrode layer 250 connected in sequence along the first direction X, wherein a second opening area 211 is provided on the second front electrode 210, a second heterojunction is formed between the second electron transport layer 220 and the second crystalline silicon film 230, a third heterojunction is formed between the second crystalline silicon film 230 and the hole transport layer 240, and the back electrode layer 250 is connected to the side of the hole transport layer away from the reflector 300, and is used to receive holes generated in the second crystalline silicon film 230.

[0023] A reflector 300, wherein the first photodetector 100 and the second photodetector 200 are both arranged on one side of the reflective surface of the reflector 300, wherein the light wave 500 to be measured enters the first photodetector 100 from the first opening area 111 at an incident angle, and after a part of the light wave 500 to be measured is transmitted by the first photodetector 100, it enters the second photodetector 200 from the second opening area 211 at the incident angle through the reflector 300; and an isolation plate 400, wherein the isolation plate 400 is arranged between the first photodetector 100 and the second photodetector 200.

[0024] It should be noted that, for ease of description, in this embodiment, the thickness direction of the first photodetector 100 or the second photodetector 200 is defined as the first direction X, and the arrangement direction of the first photodetector 100 and the second photodetector 200 is defined as the second direction Y. The first direction X and the second direction Y are arranged perpendicular to each other in the same plane.

[0025] In this embodiment, the first photodetector 100 is used to absorb most of the short-wavelength light and transmit most of the long-wavelength light, and the transmittance of the first photodetector 100 gradually increases with the increase of the wavelength, and the second photodetector 200 is used to receive and absorb the long-wavelength light transmitted by the first photodetector 100. Further, based on the structure in which the first photodetector 100 and the second photodetector 200 are arranged at intervals along the second direction Y, the heterojunction wavelength sensor in this embodiment can receive incident light waves at different angles. Specifically, the incident angle is the angle between the incident direction of the light wave 500 to be measured and the first direction X. In different implementations, the incident angle can be preferably 10° to 60° according to actual conditions. The incident angle in this embodiment is 45°.

[0026] See also Figure 1 and Figure 2 As shown, in the first photodetector 100, the first front electrode 110 is a planar hole-shaped structure, which is used to receive the incident light wave and the electrons formed in the first crystalline silicon film 130. Specifically, the incident light wave in this embodiment enters the first photodetector 100 through the first opening area 111, and the first opening area 111 is circular, and the area of ​​the first opening area 111 is 1000000μm 2 The incident light wave is incident obliquely through the first opening area 111 and then passes through the first electron transport layer 120 and the first crystalline silicon film 130 in sequence.

[0027] In this embodiment, the first electron transport layer 120 is preferably a planar two-dimensional SnO2 with a thickness of 60 nm and a doping concentration of 10 17 cm -3 , n-type doping; correspondingly, the first crystalline silicon film 130 is p-type doped, its thickness is 3mm, and its doping concentration is 3×10 17 cm -3 , which is used to absorb short-wavelength light and transmit long-wavelength light, while generating photocurrent. In this embodiment, a first heterojunction is formed at the interface between the first electron transport layer 120 and the first crystalline silicon film 130. Further, the energy difference of the valence band edge at the interface of the first heterojunction is greater than the energy difference of the conduction band edge, so as to separate the photogenerated electrons through the built-in electric field of the first heterojunction. Thereafter, the separated photogenerated electrons are absorbed by the first front electrode 110 through the first electron transport layer 120.

[0028] Correspondingly, in the second photodetector 200, the second front electrode 210 is a planar hole-shaped structure, which is used to receive the light wave transmitted by the first photodetector 100 and the electrons formed in the second crystalline silicon film 230. Specifically, the light wave enters the second photodetector 200 through the second opening area 211, and the second opening area 211 is also configured as a circle, and the area of ​​the second opening area 211 is 1000000μm 2 The incident light wave passes through the second opening area 211 after being obliquely incident, and then passes through the second electron transport layer 220, the second crystalline silicon film 230 and the hole transport layer 240 in sequence. In different embodiments, the area of ​​the first opening area 111 and the second opening area 211 can be set to 100-4000000 μm 2 The shapes of the first opening area 111 and the second opening area 211 can be configured as a circle, an ellipse, a triangle or a polygon, and the present invention does not impose any specific limitation on this.

[0029] In this embodiment, the second electron transport layer 220 is preferably a planar two-dimensional SnO2 with a thickness of 60 nm and a doping concentration of 10 17 cm -3 , and is n-type doped; the second crystalline silicon film 230 is p-type doped, with a thickness of 120 μm and a doping concentration of 3×10 17 cm -3 , which is used to absorb the light transmitted by the first photodetector 100 and generate photocurrent. The hole transport layer 240 is a planar two-dimensional structure of Spiro-OMeTAD, with a thickness of 60nm and a doping concentration of 10 18 cm -3 In different embodiments, the hole transport layer 240 can be configured as a planar two-dimensional structure with a thickness of 40-400 nm according to actual use requirements, and its substrate can be one of Spiro-OMeTAD, MoO3, NiO or WO3, and the doping concentration range can be between 10 16 ~10 19 cm -3 .

[0030] It should be noted that, in different implementations, the doping concentration range of the first crystalline silicon film 130 and the second crystalline silicon film 230 is 10 15 ~10 18 cm -3, wherein the thickness of the first crystalline silicon film 130 can be configured to be 1~6μm, and the thickness of the second crystalline silicon film 230 can be configured to be 60~150μm, thereby ensuring that the thickness of the second crystalline silicon film 230 is greater than the thickness of the first crystalline silicon film 130, thereby achieving the purpose that the second photodetector 200 can receive and absorb the light transmitted by the first photodetector 100. Similarly, the substrates of the first electron transport layer 120 and the second electron transport layer 220 can be configured to be one of SnO2, TiO2, Ga2O3, ZnO or ITO, and the thickness can be configured to be 30~300nm, and the doping concentration range of the first electron transport layer 120 and the second electron transport layer 220 is configured to be 10 15 ~10 18 cm -3 .

[0031] Furthermore, in this embodiment, a second heterojunction is formed between the second electron transport layer 220 and the second crystalline silicon film 230, and the energy difference of the valence band edge at the interface of the second heterojunction is greater than the energy difference of the conduction band edge, so as to separate the photogenerated electrons through the built-in electric field of the second heterojunction; a third heterojunction is formed between the second crystalline silicon film 230 and the hole transport layer 240, and the energy difference of the conduction band edge at the interface of the third heterojunction is greater than the energy difference of the valence band edge, so as to selectively collect the photogenerated holes through the built-in electric field of the third heterojunction.

[0032] See also Figure 1 and Figure 2 As shown, the reflector 300 in this embodiment is spaced at an equal distance from the first photodetector 100 and the second photodetector 200 in the first direction X, and can be set between 500 μm and 10 mm according to actual usage requirements. The reflective surface area of ​​the reflector 300 covers the projection area of ​​the first opening area 111 and the second opening area 211 in the first direction X to ensure that the output light of the first photodetector 100 can be reflected by the reflective surface to the inside of the second photodetector 200.

[0033] Furthermore, the surface of the isolation plate 400 is coated with a blackening treatment layer, which isolates the first photodetector 100 and the second photodetector 200 in the second direction Y. Specifically, the surface of the isolation plate 400 in this embodiment is blackened so that it can efficiently absorb visible light and near-infrared light.

[0034] Furthermore, the vertical distance between the bottom of the isolation plate 400 and the reflector 300 in this embodiment can be adjusted between 100 μm and 8 mm, and its height is greater than the height of the second photodetector 200 in the first direction X, and its width is greater than the first photodetector 100 and the second photodetector 200, thereby achieving complete isolation between the first photodetector 100 and the second photodetector 200, thereby preventing interference caused by stray light. Based on the setting of the isolation plate 400, the interference light caused by the surface reflection of the second photodetector 200 in this embodiment cannot be absorbed by the first photodetector 100, thereby avoiding the mutual interference between the two photodetectors caused by the conventional stacked sensor when the incident light is not vertically incident, and improving the accuracy of sensing.

[0035] The following describes the use process and principle of the heterojunction wavelength sensor in this embodiment: In this embodiment, the incident light wave to be sensed is incident on the first photodetector 100 at 45 degrees, and some light waves with shorter wavelengths are absorbed by the first crystalline silicon film 130 and generate photogenerated electron-hole pairs in the body thereof, and the remaining light waves are transmitted out of the first photodetector 100. Based on this, driven by the built-in electric field formed by the single heterojunction, the photogenerated electrons move toward the electron transport layer, thereby forming a photocurrent inside the first photodetector 100; Part of the light wave to be sensed transmitted by the first photodetector 100 enters the second photodetector 200 after passing through the reflector 300, and driven by the built-in electric field formed by the double heterojunction, the photogenerated electrons move toward the electron transport layer and the photogenerated holes move toward the hole transport layer 240, thereby causing the thicker crystalline silicon film to form a larger photocurrent under the action of the built-in electric field formed by the double heterojunction; By calculating the ratio of the photocurrent of the first photodetector 100 and the photocurrent of the second photodetector 200, a photocurrent ratio-wavelength curve having monotonicity within the wavelength range to be measured can be obtained, and the wavelength sensing process can be completed.

[0036] Compared with the traditional wavelength sensor, this embodiment can effectively increase the ratio of the output photocurrent, the smoothness of the ratio curve and the wavelength range of the monotonicity of the ratio curve, thereby improving the sensitivity, resolution and wavelength test range of the wavelength sensor. At the same time, the light path is regulated by using the reflector 300 and the front electrode with the opening area in the present application, which not only makes it suitable for sensing incident light waves at different angles, but also changes the traditional vertical stacking structure into a horizontal arrangement structure, thereby achieving the purpose of avoiding mutual interference between the two photodetectors.

[0037] See also Figure 3As shown, curve 31 represents the photocurrent density-wavelength curve in the first photodetector 100; curve 32 represents the photocurrent density-wavelength curve in the second photodetector 200; Figure 3 It can be seen that as the wavelength of the incident light increases, the photocurrent of the first photodetector 100 gradually increases, and then begins to decrease at a wavelength of 410nm, and the photocurrent of the second photodetector 200 begins to increase monotonically from a wavelength of 430nm. Therefore, the monotonicity of the two detectors of the wavelength sensor in the range of 450~1000nm is generally opposite.

[0038] Further, see Figure 4 As shown in FIG. 1 , in this embodiment, by changing the incident angle and calculating the photocurrent density as a ratio, the sensor is obtained when the incident angle is 30° and the incident light power density is 0.3 mW cm -2 , the photocurrent ratio-wavelength curves corresponding to TM (electric field polarization along the X direction) and TE (electric field polarization along the Z direction) waves under the conditions that the thickness of the first crystalline silicon film 130 and the second crystalline silicon film 230 are 3μm and 120μm respectively. Among them, curve 41 represents the photocurrent ratio-wavelength curve change trend of the wavelength sensor under the condition of the incident wavelength of TM waves of 200~1000nm, and curve 42 represents the photocurrent ratio-wavelength curve change trend of the wavelength sensor under the condition of the incident wavelength of TE waves of 200~1000nm. Figure 4 It can be seen that when the incident light is obliquely at 30°, the photocurrent ratio curve of TM wave and TE wave has a good monotonic increase in the wavelength range of 500~1000nm, and the difference in the ratios corresponding to TM and TE waves is not obvious. Therefore, the wavelength sensor is less affected by polarization, which proves that it is feasible to identify the wavelength of incident light by measuring the photocurrent ratio of oblique incident light.

[0039] Furthermore, the present embodiment performs multiple detections by adjusting the preset angle of the incident light. Specifically, by solving the Maxwell equations, the carrier transport equation, and the Poisson equation, the present embodiment obtains the following results when the incident wavelength is 200-1000nm, the polarization is TM wave, and the incident light power density is 0.3mWcm -2 , the photocurrent ratio-wavelength curves under the conditions that the thickness of the first and second crystalline silicon films 230 are 3 μm and 120 μm respectively, and the incident angles are 15°, 30°, 45°, and 60° respectively. For details, see Figure 5 As shown, curve 51, curve 52, curve 53, and curve 54 correspond to the photocurrent ratio-wavelength curves of the wavelength sensor when the incident angle is 15°, 30°, 45°, and 60°, respectively. Figure 5It can be seen that the horizontal heterojunction detector can work under conditions of different incident light angles. When the incident angle is within the range of 15°~60°, the ratio curves of the photocurrents of the two detectors are monotonic. Because there are differences in the wavelengths of incident light with the same current ratio between different incident light angles, in practical applications, different wavelengths of incident light can be identified according to the different angles of the incident light, which has higher accuracy and greater flexibility. In addition, if Figure 5 The data in the logarithmic coordinate system are expressed to further verify its sensing ability, see Figure 6 As shown, Figure 6 It is clearly shown that the starting point of the working range of the wavelength sensor is located at about 410nm, and it has the ability to recognize visible light, which can reflect the working ability of the heterojunction wavelength sensor under various angle conditions.

[0040] See also Figure 7 As shown, in this embodiment, when the thickness of the second crystalline silicon film 230 remains unchanged, the thickness of the first crystalline silicon film 130 is adjusted, and the photocurrent ratio-wavelength curves of the sensor are obtained in sequence, wherein curve 71, curve 72, and curve 73 correspond to the photocurrent ratio-wavelength curves of the sensor when the thickness of the first crystalline silicon is 1μm, 3μm, and 6μm, respectively. It can be seen from the figure that the sensor has the ability to recognize wavelengths when the thickness is 1μm, 3μm, and 6μm, and the sensor has a larger photocurrent ratio when the thickness is 1μm, which can prove that the sensor has a good recognition function for visible light, and as the thickness increases, the optimal sensing range of the sensor will redshift, and it has better monotonicity.

[0041] See also Figure 8 As shown, in this embodiment, when the thickness of the first crystalline silicon film remains unchanged, the thickness of the second crystalline silicon film 230 is adjusted, and the photocurrent ratio-wavelength curve of the sensor is obtained in sequence, wherein curve 81, curve 82, curve 83, and curve 84 correspond to the photocurrent ratio-wavelength curves when the thickness of the second detector crystalline silicon film is 60μm, 90μm, 120μm, and 150μm, respectively. Figure 8 It can be seen that within the above thickness range, the wavelength sensor still has good wavelength sensing capability, and as the thickness increases, the photocurrent ratio-wavelength curve of the sensor shows a more stable monotonicity. Preferably, the wavelength sensor has the best recognition capability when the thickness is 120 μm. Comparative Example

[0042] The comparative example adopts a conventional vertical stacked detector structure, and changes the incident light to vertical incidence. The incident wavelength and incident light power density are the same as those in Example 1. Under this condition, the photocurrent ratio-wavelength curve is measured. For details, see Fig. 9 As shown by Fig. 9It can be seen that the curve produces obvious and disordered fluctuations around 520nm, and the monotonicity of the curve is poor. This can be attributed to the fact that the long-wavelength light passing through the first photodetector is reflected on the surface of the second photodetector and returns to the first photodetector, thereby interfering with the light absorption and light response of the first detector. Therefore, it can be confirmed that the performance of the heterojunction wavelength sensor used in this application has obvious advantages over conventional stacked wavelength sensors.

[0043] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A heterojunction wavelength sensor, characterized in that: include: A first photodetector, comprising a first front electrode, a first electron transport layer, a first crystalline silicon film and a transparent electrode layer connected in sequence along a first direction, wherein a first opening area is provided on the first front electrode, a first heterojunction is formed between the first electron transport layer and the first crystalline silicon film, and the transparent electrode layer is connected to the first crystalline silicon film; a second photodetector, wherein the second photodetector is arranged at intervals with the first photodetector along a second direction, and comprises a second front electrode, a second electron transport layer, a second crystalline silicon film, a hole transport layer and a back electrode layer connected in sequence along the first direction, wherein a second opening area is provided on the second front electrode, a second heterojunction is formed between the second electron transport layer and the second crystalline silicon film, a third heterojunction is formed between the second crystalline silicon film and the hole transport layer, and the back electrode layer is connected to the hole transport layer; A reflector, wherein the first photodetector and the second photodetector are both arranged on one side of a reflective surface of the reflector, the light wave to be measured is incident on the first photodetector from the first opening area at a preset angle, and a part of the light wave to be measured is transmitted by the first photodetector and then incident on the second photodetector from the second opening area at the preset angle through the reflector; An isolation plate is disposed between the first photodetector and the second photodetector.

2. The heterojunction wavelength sensor according to claim 1, characterized in that: The preset angle is the angle between the incident direction of the light wave to be measured and the first direction, and the preset angle is 10°~60°.

3. The heterojunction wavelength sensor according to claim 1, characterized in that: The first crystalline silicon film is a p-type doping structure, and its doping concentration range is 10 15 ~10 18 cm -3 , with a thickness of 1 to 6 μm; the second crystalline silicon film is a p-type doping structure, with a doping concentration range of 10 15 ~10 18 cm -3 , with a thickness of 60-150 μm; the first electron transport layer and the second electron transport layer substrate are one of SnO2, TiO2, Ga2O3, ZnO or ITO, and the thickness is 30-300 nm in a planar two-dimensional structure, the first electron transport layer and the second electron transport layer are both n-type doped structures, and the doping concentration range is 10 15 ~10 18 cm -3 .

4. The heterojunction wavelength sensor according to claim 1, characterized in that: The first front electrode and the second front electrode are both planar hole structures, and the area of ​​the first opening area and the area of ​​the second opening area are both 100-4000000 μm 2 ; The first opening area and the second opening area are both configured as one of a circle, an ellipse, a triangle or a polygon.

5. The heterojunction wavelength sensor according to claim 1, characterized in that: The energy difference at the valence band edge at the first heterojunction interface is greater than the energy difference at the conduction band edge; the energy difference at the valence band edge at the second heterojunction interface is greater than the energy difference at the conduction band edge; the energy difference at the conduction band edge at the third heterojunction interface is greater than the energy difference at the valence band edge.

6. The heterojunction wavelength sensor according to claim 1, characterized in that: The hole transport layer is configured as a planar two-dimensional structure with a thickness of 40-400 nm, and its substrate is one of Spiro-OMeTAD, MoO3, NiO or WO3, which is a p-type doped structure, and the doping concentration range is 10 16 ~10 19 cm -3 .

7. The heterojunction wavelength sensor according to claim 1, characterized in that: The reflector is spaced equidistantly from the first photodetector and the second photodetector in the first direction and is 500 μm to 10 mm. The reflective surface area of ​​the reflector covers the projection areas of the first opening area and the second opening area in the first direction.

8. The heterojunction wavelength sensor according to claim 1, characterized in that: The surface of the isolation plate is covered with a blackening treatment layer, which isolates the first photodetector and the second photodetector in the second direction.

9. A heterojunction wavelength sensing method, characterized in that: The heterojunction wavelength sensor according to any one of claims 1 to 8 is used to sense the wavelength of a light wave to be measured, comprising: Step S1, allowing the light wave to be measured to enter the first photodetector at a preset angle, part of the light wave to be measured is absorbed by the first crystalline silicon film, and forms a first photocurrent under the action of the built-in electric field of the first heterojunction, and the rest of the light wave to be measured is transmitted out of the first photodetector; Step S2, reflecting the light wave to be measured transmitted through the first photodetector to the second photodetector through a reflector; Step S3, the light wave to be measured reflected into the second photodetector is absorbed by the second crystalline silicon film, and a second photocurrent is formed under the action of the built-in electric field of the second heterojunction and the third heterojunction; Step S4, respectively detecting the first photocurrent response intensity and the second photocurrent response intensity; Step S5, fitting a photocurrent ratio-wavelength curve having monotonicity within the wavelength range to be measured by the ratio of the first photocurrent response intensity to the second photocurrent response intensity, so as to complete wavelength sensing.

10. The heterojunction wavelength sensing method according to claim 9, characterized in that: In steps S1 to S5, the first photodetector and the second photodetector are isolated by an isolation plate; in step S1, the light wave to be measured is incident on the first photodetector through the first opening area at a preset angle, and the first crystalline silicon film absorbs part of the light to be measured and transmits the rest of the light to be measured; In step S2, the transmitted light of the first photodetector is incident through the second opening area under the action of the reflector.

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