A heterojunction wavelength sensor and a sensing method

Abstract

The present invention provides a heterojunction wavelength sensor and a sensing method, which include: a first photodetector, wherein a first opening area is provided on a first front electrode, and a first heterojunction is formed between a first electron transport layer and a first crystalline silicon thin film; a second photodetector, which is arranged at an interval from the first photodetector along a second direction, wherein a second opening area is provided on a second front electrode, a second heterojunction is formed between a second electron transport layer and a second crystalline silicon thin film, and a third heterojunction is formed between the second crystalline silicon thin film and a hole transport layer; a mirror, both the first photodetector and the second photodetector are arranged on one side of the reflecting surface of the mirror; a separator, which is arranged between the first photodetector and the second photodetector. Compared with the conventional sensing structures at the present stage, the present invention has the advantages of simple structure, low production and processing cost, wide application range, strong use flexibility, and can effectively reduce the reflection error between devices.

Description

Technical Field

[0001] The present invention relates to the technical field of sensors, and particularly to a heterojunction wavelength sensor and a sensing method. Background Art

[0002] In the current field of optical sensing technology, as a key component, the performance of wavelength sensors directly affects the effects of many application scenarios. The wavelength sensor without a filtering element has received extensive attention in recent years due to its unique advantages. However, there are still many problems to be solved in the comprehensive performance indicators of the existing publicly available technical solutions, which severely restricts its further development and application.

[0003] First of all, in the wavelength sensing applications in the indoor visible near-infrared band, most wavelength sensors without filtering elements adopt a vertically stacked structure. Although this structure realizes the detection of wavelengths to a certain extent, it has obvious defects. When a single photodetector is working, its optical response signal is extremely vulnerable to the interference of reflected light at the internal interface of the sensor. When light enters the sensor, reflection occurs at the interfaces of different photodetectors. These reflected lights will enter the photodetector again and be superimposed on the effective optical signal, resulting in a deviation in the signal received by the photodetector. In actual application scenarios, such as indoor environmental monitoring and biomedical detection, this interference will greatly reduce the accuracy of wavelength identification, thereby affecting the accurate judgment of environmental parameters or the accurate analysis of biological samples.

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

[0005] Thirdly, the wavelength sensors reported at the current stage generally adopt PIN junction or PN junction photodetectors. During the manufacturing process of such detectors, complex doping processes are required to precisely control the doping concentration and depth. Precise control of the doping concentration and depth requires highly sophisticated equipment and complex technological processes, which not only increases the difficulty and cost of device manufacturing but also easily introduces errors. In actual operation, such sensors determine the wavelength by calculating the ratio of the optical response signals of two photodetectors. However, due to the influence of the internal structure of the detectors and the manufacturing process, the obtained monotonic curve has a small value and is not smooth enough. This results in a low wavelength recognition accuracy and a small resolution, making it difficult to meet application scenarios with high requirements for wavelength measurement accuracy, such as wavelength division multiplexing technology in optical communication, high-precision spectral analysis, etc.

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

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

[0008] 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 thin 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 thin film, and the transparent electrode layer is connected to the side of the first crystalline silicon thin film facing the mirror; a second photodetector, the second photodetector and the first photodetector are arranged at intervals along a second direction, and it includes a second front electrode, a second electron transport layer, a second crystalline silicon thin 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 thin film, and a third heterojunction is formed between the second crystalline silicon thin film and the hole transport layer, and the back electrode layer is connected to the side of the hole transport layer away from the mirror; a mirror, both the first photodetector and the second photodetector are arranged on the reflection surface side of the mirror, and the light wave to be measured is incident on the first photodetector from the first opening area at a preset angle. After part of the light wave to be measured is transmitted by the first photodetector, it is incident on the second photodetector from the second opening area through the mirror at the preset angle. Wherein, the preset angle is the included angle between the incident direction of the light wave to be measured and the first direction, and the preset angle is 10° to 60°; a separator, the separator is arranged between the first photodetector and the second photodetector.

[0009] In an embodiment of the present invention, the first crystalline silicon thin film is a p-type doped structure, and its doping concentration range is 10 15 ~10 18 cm -3 , and its thickness is 1 to 6 μm; the second crystalline silicon thin film is a p-type doped structure, and its doping concentration range is 10 15 ~10 18 cm -3 , and its thickness is 60 to 150 μm; the substrates of the first electron transport layer and the second electron transport layer are one of SnO2, TiO2, Ga2O3, ZnO or ITO, and both are planar two-dimensional structures with a thickness of 30 to 300 nm. 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 .

[0010] In one embodiment of the present invention, both the first front electrode and the second front electrode are planar hole-like structures, and the areas of the first opening region and the second opening region are both 100 - 4000000 μm 2 ; the first opening region and the second opening region are each configured as one of a circle, an ellipse, a triangle, or a polygon.

[0011] 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.

[0012] In one embodiment of the present invention, 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. It is a p-type doped structure, and the doping concentration range is 10 16 ~10 19 cm -3 .

[0013] In one embodiment of the present invention, the reflector is equidistant from the first photodetector and the second photodetector in the first direction, and the distance is 500 μm - 10 mm. The reflecting surface area of the reflector covers the projected areas of the first opening region and the second opening region in the first direction; the surface of the separator plate is coated with a blackening treatment layer, which isolates the first photodetector and the second photodetector in the second direction.

[0014] The present invention also provides a heterojunction wavelength sensing method, which uses the above-mentioned heterojunction wavelength sensor to sense the wavelength of a light wave to be measured. It includes: Step S1, making the light wave to be measured enter the first photodetector at a preset angle. Part of the light wave to be measured is absorbed by the first crystalline silicon thin film, and a first photocurrent is formed under the action of the built-in electric field in the first heterojunction. The remaining part of the light wave to be measured passes through the first photodetector; Step S2, reflecting the light wave to be measured that has passed through the first photodetector to the second photodetector through the reflector; Step S3, the light wave to be measured reflected to the second photodetector is absorbed by the second crystalline silicon thin film, and a second photocurrent is formed under the action of the built-in electric fields in the second heterojunction and the third heterojunction; Step S4, respectively detecting the response intensity of the first photocurrent and the response intensity of the second photocurrent; Step S5, fitting a photocurrent ratio - wavelength curve with monotonicity in the wavelength range to be measured through the ratio of the response intensity of the first photocurrent and the response intensity of the second photocurrent to complete wavelength sensing.

[0015] In one embodiment of the present invention, in steps S1 to S5, the first photodetector and the second photodetector are isolated by a partition plate; in step S1, the light wave to be measured enters the first photodetector through the first opening area at a preset angle, the first crystalline silicon thin film absorbs part of the light to be measured, and transmits the remaining light to be measured; in step S2, the transmitted light of the first photodetector enters through the second opening area under the action of the mirror.

[0016] The above technical solution of the present invention has the following advantages compared with the prior art:

[0017] For the heterojunction wavelength sensor and the sensing method thereof of the present invention, the single heterojunction structure in the first photodetector and the relatively thin crystalline silicon mainly absorb light with short wavelengths, and at the same time, the double heterojunction structure in the second photodetector and the relatively thick crystalline silicon mainly absorb light with long wavelengths. Thus, the ratio of the output photocurrent can be effectively increased, the smoothness of the ratio curve and the wavelength range that can be sensed can be improved. Compared with the conventional silicon-based optoelectronic 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, in the present application, the optical path is regulated by using a mirror and a front electrode provided with an opening area, which not only enables it to be applicable to sensing incident light waves at different angles, but also can change the traditional vertically stacked structure into a horizontally arranged structure, thereby achieving the purpose of avoiding mutual interference between the two photodetectors. Based on this, compared with the conventional sensing structures at the present stage, the present application has the advantages of simple structure, low production and processing cost, wide application range, strong use flexibility, and can effectively reduce the reflection error between devices. Description of the Drawings

[0018] In order to make the content of the present invention easier to be clearly understood, the present invention will be further described in detail below according to the specific embodiments of the present invention in conjunction with the drawings.

[0019] Figure 1 is a schematic structural diagram of a heterojunction wavelength sensor in a preferred embodiment of the present invention;

[0020] Figure 2 is Figure 1 the working principle diagram of the shown heterojunction wavelength sensor under zero bias voltage;

[0021] Figure 3 is Figure 1 the photocurrent density-wavelength curve of the first photodetector and the second photodetector in the shown heterojunction wavelength sensor when the incident wavelength range is 200-1000 nm, the incident angle is 45°, and the incident optical power density is 0.3 mWcm -2 ;

[0022] Figure 4 is Figure 1 The photocurrent ratio - wavelength curves corresponding to TE and TM waves of the heterojunction wavelength sensor shown under illumination with an incident angle of 30° and an incident optical power density of 0.3 mW / cm -2 ;

[0023] Figure 5 is Figure 1 The photocurrent ratio - wavelength curves corresponding to the heterojunction wavelength sensor shown under the conditions of an incident optical power density of 0.3 mW / cm -2 , incident angles of 15°, 30°, 45°, and 60°;

[0024] Figure 6 is Figure 5 The representation form of the data in Figure 5 in the logarithmic coordinate system;

[0025] Figure 7 is to adjust Figure 1 The photocurrent ratio - wavelength curves corresponding to the heterojunction wavelength sensor shown after adjusting the thickness of the first crystalline silicon thin film under the conditions of an incident wavelength of 200 - 1000 nm, polarization of TM wave, incident angle of 45°, and incident optical power density of 0.3 mW / cm -2 ;

[0026] Figure 8 is to adjust Figure 1 The photocurrent ratio - wavelength curves corresponding to the heterojunction wavelength sensor shown after adjusting the thickness of the second crystalline silicon thin film under the conditions of an incident wavelength of 200 - 1000 nm, polarization of TM wave, incident angle of 45°, and incident optical power density of 0.3 mW / cm -2 ;

[0027] Figure 9 is the photocurrent ratio - wavelength curve obtained when the stacked wavelength sensor in the comparative example is perpendicularly incident with the optical wave to be measured.

[0028] Explanation of reference numerals in the drawings of the specification: 100, the first photodetector; 110, the first front electrode; 111, the first opening area; 120, the first electron transport layer; 130, the first crystalline silicon thin film; 140, the transparent electrode layer; 200, the second photodetector; 210, the second front electrode; 211, the second opening area; 220, the second electron transport layer; 230, the second crystalline silicon thin film; 240, the hole transport layer; 250, the back electrode layer; 300, the mirror; 400, the separator; 500, the optical wave to be measured; X, the first direction; Y, the second direction. Detailed implementation manners

[0029] The present invention will be further described below in conjunction with the drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it, but the embodiments cited do not limit the present invention.

[0030] Embodiment 1

[0031] See also Figure 1 As 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.

[0032] 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.

[0033] 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.

[0034] 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 that 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°.

[0035] 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.

[0036] 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 3 μm, 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.

[0037] Correspondingly, in the second photodetector 200, the second front electrode 210 is a planar hole-like structure, which is used to receive the light wave transmitted by the first photodetector 100 and receive the electrons formed in the second crystalline silicon thin film 230. Specifically, the light wave enters the second photodetector 200 through the second opening area 211. The second opening area 211 is also configured as a circle, and the area of the second opening area 211 is 1000000 μm 2 . After the incident light wave is obliquely incident through the second opening area 211, it sequentially passes through the second electron transport layer 220, the second crystalline silicon thin film 230, and the hole transport layer 240. In different embodiments, the areas 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 one of a circle, an ellipse, a triangle, or a polygon, and the present invention does not make specific limitations thereon.

[0038] In this embodiment, the second electron transport layer 220 is preferably SnO2 with a planar two-dimensional structure, its thickness is 60 nm, and its doping concentration is 10 17 cm -3 , and it is n-type doped; the second crystalline silicon thin film 230 is p-type doped, its thickness is 120 μm, and its doping concentration is 3×10 17 cm -3 , which is used to absorb the light transmitted by the first photodetector 100 and generate a photocurrent at the same time. The hole transport layer 240 is Spiro-OMeTAD with a planar two-dimensional structure, its thickness is 60 nm, and its doping concentration is 10 18 cm -3 , and it is p-type doped. 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 usage requirements, and its substrate can be one of Spiro-OMeTAD, MoO3, NiO, or WO3, and the doping concentration range can be 10 16 ~10 19 cm -3 .

[0039] It should be noted that in different embodiments, the doping concentration ranges of the first crystalline silicon thin film 130 and the second crystalline silicon thin film 230 are 10 15 ~10 18 cm -3, wherein the thickness of the first crystalline silicon thin film 130 can be configured to be 1-6 μm, and the thickness of the second crystalline silicon thin film 230 can be configured to be 60-150 μm, thereby ensuring that the thickness of the second crystalline silicon thin film 230 is greater than that of the first crystalline silicon thin film 130, and further achieving the purpose that the second photodetector 200 can receive and absorb the transmitted light of the first photodetector 100. Similarly, the substrates of the first electron transport layer 120 and the second electron transport layer 220 can both be configured to be one of SnO2, TiO2, Ga2O3, ZnO or ITO, and the thickness can both be configured to be 30-300 nm, 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 。

[0040] Furthermore, in this embodiment, a second heterojunction is formed between the second electron transport layer 220 and the second crystalline silicon thin 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 to separate photo-generated electrons through the built-in electric field in the second heterojunction; a third heterojunction is formed between the second crystalline silicon thin 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 to selectively collect photo-generated holes through the built-in electric field in the third heterojunction.

[0041] See Figure 1 and Figure 2 As shown, the distance between the mirror 300 and the first photodetector 100 and the second photodetector 200 in the first direction X in this embodiment is equal, and it can be set between 500 μm and 10 mm according to actual usage requirements. The reflection surface area of the mirror 300 covers the projection areas 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 reflection surface into the second photodetector 200.

[0042] Furthermore, the surface of the separator 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 separator 400 in this embodiment is blackened so that it can efficiently absorb visible light and near-infrared light.

[0043] Furthermore, the vertical distance between the bottom of the partition plate 400 and the mirror 300 in this embodiment can be adjusted between 100 μm and 8 mm. Its height is greater than the height of the second photodetector 200 in the first direction X, and its width is greater than that of the first photodetector 100 and the second photodetector 200, thereby achieving complete isolation between the first photodetector 100 and the second photodetector 200, and further preventing stray light from causing interference. Based on the setting of the partition plate 400, the interfering light caused by the surface reflection of the second photodetector 200 in this embodiment cannot be absorbed by the first photodetector 100, thus avoiding the mutual interference between the two photodetectors when the incident light is not vertically incident in a conventional stacked sensor and improving the sensing accuracy.

[0044] The following describes the usage process and principle of the heterojunction wavelength sensor in this embodiment:

[0045] In this embodiment, the incident light wave to be sensed is incident on the first photodetector 100 at an angle of 45°. Some light waves with shorter wavelengths will be absorbed by the first crystalline silicon thin film 130, and photo-generated electron-hole pairs will be generated in its body. The remaining light waves will transmit through the first photodetector 100. Based on this, under the built-in electric field formed by a single heterojunction, the photo-generated electrons move towards the electron transport layer, thereby forming a photocurrent inside the first photodetector 100;

[0046] Some of the light waves to be sensed transmitted through the first photodetector 100 enter the second photodetector 200 after passing through the mirror 300. Under the drive of the built-in electric field formed by the double heterojunction, the photo-generated electrons move towards the electron transport layer and the photo-generated holes move towards the hole transport layer 240, thereby enabling a larger photocurrent to be formed in the relatively thick crystalline silicon thin film under the action of the built-in electric field formed by the double heterojunction;

[0047] By calculating the ratio of the photocurrent of the first photodetector 100 to the photocurrent of the second photodetector 200, a photocurrent ratio-wavelength curve with monotonicity in the wavelength range to be measured can be obtained, and thus the wavelength sensing process can be completed.

[0048] Compared with traditional wavelength sensors, 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, in this application, the optical path is regulated by using the mirror 300 and the front electrode provided with an opening area, which not only enables it to be applicable to sensing incident light waves at different angles, but also can change the traditional vertical stacking structure into a horizontal arrangement structure, thereby achieving the purpose of avoiding mutual interference between the two photodetectors.

[0049] See 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; from Figure 3 it can be seen that as the wavelength of the incident light increases, the photocurrent of the first photodetector 100 gradually increases first and starts to decrease at a wavelength of 410 nm, and the photocurrent of the second photodetector 200 starts to increase monotonically from a wavelength of 430 nm. Therefore, the monotonicity of the two detectors of this wavelength sensor is generally opposite in the range of 450-1000 nm.

[0050] Furthermore, referring to Figure 4 as shown, in this embodiment, by changing the incident angle and calculating the ratio of the photocurrent density, 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 are obtained under the conditions that the incident angle is 30°, the incident optical power density is 0.3 mW / cm -2 , and the thicknesses of the first crystalline silicon thin film 130 and the second crystalline silicon thin film 230 are 3 μm and 120 μm respectively. Among them, curve 41 represents the change trend of the photocurrent ratio-wavelength curve of the TM wave with an incident wavelength of 200-1000 nm under this condition for this wavelength sensor, and curve 42 represents the change trend of the photocurrent ratio-wavelength curve of the TE wave with an incident wavelength of 200-1000 nm under this condition for this wavelength sensor. From Figure 4 it can be seen that when obliquely incident at 30°, the photocurrent ratio curves of the TM wave and the TE wave have good monotonic increase in the wavelength range of 500-1000 nm, and the difference in the ratio values corresponding to the TM and TE waves is not obvious. Therefore, this wavelength sensor is less affected by polarization, which further proves that it is feasible to identify the incident light wavelength by measuring the photocurrent ratio of obliquely incident light.

[0051] Furthermore, in this embodiment, multiple detections are carried out by adjusting the preset angle of the incident light. Specifically, in this embodiment, by solving the Maxwell equations, the carrier transport equation, and the Poisson equation, the photocurrent ratio-wavelength curves with incident angles of 15°, 30°, 45°, and 60° are obtained under the conditions that the incident wavelength is 200-1000 nm, the polarization is the TM wave, the incident optical power density is 0.3 mW / cm -2 , and the thicknesses of the first and second crystalline silicon thin films 230 are 3 μm and 120 μm respectively. Specifically, referring to Figure 5 as shown, curves 51, 52, 53, and 54 respectively correspond to the photocurrent ratio-wavelength curves of this wavelength sensor when the incident angles are 15°, 30°, 45°, and 60°. From Figure 5It can be seen that the heterojunction detector with a horizontal structure can work under the conditions of incident light at different angles. When the incident angle is within the range of 15° to 60°, the ratio curve of the photocurrents of the two detectors shows monotonicity. Moreover, because there are differences in the incident light wavelengths with the same current ratio between different incident angles of light, in practical applications, different wavelengths of incident light can be identified according to different angles of incident light, with higher accuracy and stronger flexibility. In addition, if the Figure 5 data in is represented in a logarithmic coordinate system to further verify its sensing ability, see specifically Figure 6 as shown, Figure 6 which clearly shows that the starting point of the working range of the wavelength sensor is around 410 nm, and it has the ability to identify visible light. Thus, the working ability of this heterojunction wavelength sensor under various angle conditions can be demonstrated.

[0052] See Figure 7 as shown. In this embodiment, when the thickness of the second crystalline silicon thin film 230 remains unchanged, after adjusting the thickness of the first crystalline silicon thin film 130, the photocurrent ratio - wavelength curves of this sensor are obtained in sequence. Among them, curve 71, curve 72, and curve 73 respectively correspond to the photocurrent ratio - wavelength curves of this sensor when the thickness of the first crystalline silicon is 1 μm, 3 μm, and 6 μm. It can be seen from the figure that the sensor has the ability to identify wavelengths when the thickness is 1 μm, 3 μm, and 6 μm, and when the thickness is 1 μm, the sensor has a relatively large photocurrent ratio. Thus, it can be proved that this sensor has a good recognition function for visible light, and as the thickness increases, the best sensing range of the sensor will redshift, and at the same time, it has better monotonicity.

[0053] See Figure 8 as shown. In this embodiment, when the thickness of the first crystalline silicon thin film remains unchanged, after adjusting the thickness of the second crystalline silicon thin film 230, the photocurrent ratio - wavelength curves of this sensor are obtained in sequence. Among them, curve 81, curve 82, curve 83, and curve 84 respectively correspond to the photocurrent ratio - wavelength curves of the second detector crystalline silicon thin film with thicknesses of 60 μm, 90 μm, 120 μm, and 150 μm. From Figure 8 it can be seen that within the above - mentioned thickness range, the wavelength sensor still has good wavelength sensing ability, and as the thickness increases, the photocurrent ratio - wavelength curve of the sensor shows more stable monotonicity. Preferably, when the thickness is 120 μm, the wavelength sensor has the best recognition ability.

[0054] Comparative example

[0055] The comparative example adopts a conventional vertically stacked detector structure, and changes the incident light to vertical incidence. Its 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, see specifically Figure 9 as shown. FromFigure 9 It can be seen that the curve produces obvious and disordered fluctuations around 520 nm, 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 adopted in this application has obvious advantages compared with the conventional stacked wavelength sensor.

[0056] Obviously, the above embodiments are merely examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill 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 enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present 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 the 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 through the reflector at the preset angle, wherein 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°; 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 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 to 6 μm; 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 to 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 to 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 .

3. 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 to 4,000,000 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.

4. 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.

5. 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 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 .

6. 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.

7. 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.

8. A heterojunction wavelength sensing method, characterized in that: The heterojunction wavelength sensor according to any one of claims 1 to 7 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.

9. The heterojunction wavelength sensing method according to claim 8, 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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